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NetLogo 4.0 User Manual - scstevenson

1. print a gt array 0 1 4 9 16 print array item a 0 gt 0 print array item a 3 gt 9 array set a 3 50 print a gt array 0 1 4 50 16 Table example let dict table make table put dict turtle cute table put dict bunny cutest print dict gt table turtle gt cute bunny gt cutest print table length dict gt 2 print table get dict turtle gt cute print table get dict leopard gt 0 print table keys dict gt turtle bunny Known issues When you export a NetLogo world using the export world command or Export World menu item arrays and tables are exported by value This means that if you have the same array or table stored in more than one location then when it is exported and re imported there will now be distinct arrays or tables in the places the places the original array or table appeared These duplicates will initially contain the same values but if one duplicate is altered the others will not change Array primitives array from list array from list list Reports a new array containing the same items in the same order as the input list array item 196 Array and Table Extensions NetLogo 4 0 User Manual array item array index Reports the item in the given array with the given index ranging from zero to the length of the array minus one array set array set array index value Sets the item in the given array wi
2. display labels do plot end To find a fragment of code in the procedures click on the Find button in the Procedures Toolbar and the Find dialog will appear 00 Find Find sheep Replace with wolves M ignore case M Wrap around Replace All C Replace Replace amp Find Previous C Next You may enter either a word or phrase to find or a word or phrase to find and one to replace it with The Ignore case checkbox controls whether the capitalization must be the same to indicate a match If the Wrap around checkbox is checked the entire Procedures tab will be checked for the phrase starting at the cursor position when it reaches the end it will return to the top otherwise only the area from the cursor position to the end of the Procedures tab will be searched The Next and Previous buttons will move down and up to find another occurrence of the search phrase Replace changes the currently selected phrase with the replace phrase and Replace amp Find changes the selected phrase and moves to the next occurrence Replace all will change all instances of the the find phrase in the search area with the replace phrase To find a particular procedure definition in your code use the Procedures popup menu in the Procedures Toolbar The menu lists all procedures in alphabetical order The Shift Left Shift Right Comment and Uncomment items on the Edit menu are used in the proce
3. 233 HOW do Stop forea ch ias bata erra a a a a 233 B haviorS Patan gp 233 How do measure runs every n tickSB oooooooccccccnnonococnnnnoncnnnnnononncnnnnnccnnnnnnnnnnnnnncncnannnnns 234 I m varying a global variable declared in the Procedures tab but it doesn t work A nats aah oa E 234 Why are some of my results cut off in Excel e ererreaeeeanaana 234 EXIGNSIONS 4k fate ro O DD ae ah da nc aa CS IL oh E ae A ta 234 I m writing an extension Why does the compiler say it can t find org nlogo api 234 Net O Go DICTOM ANY ss isis setie ck eciececees A T 235 Categ riE Sci Six sch peer cried nata si wine they ni e seiner 235 Turtle related se 200 BAN ao ao EA OS ed dao de E a da ol et Bae 235 Patches n A 235 ANS diana A A A aan aes 235 GOES ad de he ce a ahaa ne Nek do done Din ad 235 Control flow and NO CIG srssucesedncg ais A Rg pad a Soda nua ad 236 NetLogo 4 0 User Manual Table of Contents NetLogo Dictionary AY A C d 6 SRS eeprom REINA DES A 236 PerSDeCIIVO icono aid lo sara 236 HUBNCE iii ds A RS A A a ae Aa 236 INDUT OUTDUL avia id 236 JEI GS tra teats eia ss EES eda Ret coh ana Macias te Stace A di Mana T ae Rane A Ae at 236 BLES Fi e e RO sad 236 SO RAM ese dai OE RE RE EDER tee 237 Mainemalical usinas silt E o 237 Plot isc cd 237 A A eee eS etn 237 IMIOWIG tte SA ON Ye ae ad E O Phe da Sad Ne A Baer E o tA orca 237 IM ii 237 Built in Vanables nia AA AA A o A A 237 PP pda aa
4. round item 0 hubnet message and round item 1 hubnet message Plot Updates on the Clients If plot mirroring is enabled in the HubNet Control Center and a plot in the NetLogo model changes and a plot with the exact same name exists on the clients a message with that change is sent to the clients causing the client s plot to make the same change For example let s pretend there is a HubNet model that has a plot called Milk Supply in NetLogo and the clients Milk Supply is the current plot in NetLogo and in the Command Center you type plot 5 This will cause a message to be sent to all the clients telling them that they need to plot a point with a y value of 5 in the next position of the plot Notice if you are doing a lot of plotting all at once this can generate a lot of plotting messages to be sent to the clients 174 HubNet Authoring Guide Logging NetLogo s logging facility allows researchers to record students actions for later analysis Logging in NetLogo once initiated is invisible to the user The researcher can choose the type of events logged through a configuration file NetLogo uses the Log4j package for logging If you have previous experience with this package you ll find logging in NetLogo familiar Starting logging This depends on what operating system you are using Mac OS X or Windows There is a special logging launcher in the NetLogo directory called NetLogo Logging Double click on the icon
5. Mac users note that Mac OS X 10 2 and 10 3 had a fairly low memory limit for Java applets namely 64 megabytes Historically Mac OS X 10 4 had the same limit but a recent Java update raised it to 96 megabytes You can get the Java update from Apple through Software Update Mac OS X 10 5 will presumably have the higher limit as well If your browser is using the browser plug in that comes with the Sun JDK or JRE then instructions for starting the Java Plug In Control Panel are available here In the Advanced tab of the Control Panel add the following to the Java Runtime Parameters field Xms16M Xmx1024M Extensions Many extensions can be used in applets simply upload the directory containing the extension jar into the same directory as the model Extensions that require additional external jars don t work from applets This includes the sound and gogo extensions Known Issues e Extensions that require external jars don t work from applets e the 3D view does not work in applets e the code generator is not used in applets which means that models will run somewhat slower e web servers that return custom error messages may cause java exceptions See the FAQ for the workaround 146 Applets Shapes Editor Guide The Turtle and Link Shape Editors allows you to create and save turtle and link designs NetLogo uses fully scalable and rotatable vector shapes which means you can create designs by combining basic geometric eleme
6. On Windows the NetLogo directory can be found at C Program Files unless you chose a different location when you installed NetLogo Linux and others from the command line start NetLogo like this java server Xmsl16M Xmx1024M cp NetLogo jar org nlogo app App logging netlogo_logging xml You can replace netlogo_logging xml with any valid log4j xml configuration file which will be discussed in more detail later Using logging When NetLogo starts up it will ask for a user name This name will appear in all the logs generated during this session Where logs are stored Logs are stored in the OS specific temp directory On most Unix like systems including MacOS that is tmp On Windows XP logs can be found in c 1Documents and Settings lt user gt Local Settings Temp where lt user gt is the logged in user and on Windows Vista the logs can be found in c Users lt user gt AppData Local Temp There are two convenience commands that will help you manage the logs zip log files filename will gather all the logs in the temp directory and put them in one zip file at the location specified After doing zip log files the existing logs are not deleted you can do so explicitly by using __delete log files Logging 175 NetLogo 4 0 User Manual The following is a chart describing the name of the loggers available the type of events each logs at what level and provides a sample output using the XMLLayout All the lo
7. 84 Chiff 85 Charang 86 Voice 87 Fifths 88 Bass and Lead Synth Pad 89 New Age 90 Warm 91 Polysynth 92 CROIT 93 Bowed 94 Metal 95 Halo 96 Sweep Synth Effects 97 Rain 98 Soundtrack 99 Crystal 100 Atmosphere 101 Brightness 102 Goblins 103 Echoes 104 Sci fi Ethnic 105 Sitar 106 Banjo 107 Shamisen 108 Koto 109 Kalimba 110 Bag pipe 111 Fiddle 12 Shanai Percussive 13 Tinkle Bell 114 Agogo 115 Steel Drums 116 Woodblock 117 Taiko Drum 18 Melodic Tom 119 Synth Drum 120 Reverse Cymbal Sound Effects 121 Guitar Fret Noise 203 58 59 60 61 62 63 64 204 Trombone Tuba Muted Trumpet French Horn Brass Section Synth Brass 1 Synth Brass 2 NetLogo 4 0 User Manual 122 123 124 12D 126 127 128 Breath Noise Seashore Bird Tweet Telephone Ring Helicopter Applause Gunshot Sound Extension GoGo Extension What is the GoGo Board The GoGo Board extension lets you connect NetLogo to the physical world using sensors motors light bulbs LEDs relays and other devices The GoGo Extension for NetLogo provides primitives to communicate with a GoGo board via a serial interface A GoGo Board is an open source easy to build low cost general purpose board especially designed to be used in educational projects It was created by_Arnan Sipitakiat at the MIT Media Lab A GoGo Board has 8 sensor ports and 4 output po
8. gt strin empty gt true empty string gt false first string gt s item 2 string gt r last string gt g length string gt 6 member s string gt true member rin string gt true member ron string gt false position s string gt 0 position rin string gt 2 position ron string gt false remove r string gt sting remove s strings gt tring replace item 3 String o gt strong reverse string gt gnirts A few primitives are specific to strings such as is string substring and word is string string gt true is string 37 gt false substring string 2 5 gt rin word tur tle gt turtle Strings can be compared using the lt gt lt and gt operators If you need to embed a special character in a string use the following escape sequences e n newline e t tab e double quote e backslash Output This section is about output to the screen Output to the screen can also be later saved to a file using the export output command If you need a more flexible method of writing data to external files see the next section File I O The basic commands for generating output to the screen in NetLogo are print show type and write These commands send their output to the Command Center For full details on these four commands see their entries in the NetLogo Dictionary Here is
9. print movie status gt No movie movie start print movie status gt 0 frames frame rate 15 movie grab view print movie status 1 frames frame rate 15 size 315x315 294 NetLogo Dictionary NetLogo 4 0 User Manual my lt breeds gt my links my lt breeds gt my links Reports an agentset of all undirected links connected to the caller ere 5 ask turtle 0 create links with other turtles show my links prints the agentset containing all links since all the links we created were with turtle 0 ask turtle 1 show my links shows an agentset containing the link O 1 end my in lt breeds gt my in links my in lt breeds gt my in links Reports an agentset of all the directed links coming in from other nodes to the caller Cre 5 ask turtle 0 create links to other turtles show my in links shows an empty agentset ask turtle 1 show my in links shows an agentset containing the link 0 1 my out lt breeds gt my out links my out lt breeds gt my out links Reports an agentset of all the directed links going out from the caller to other nodes crt 5 NetLogo Dictionary 295 NetLogo 4 0 User Manual ask turtle 0 create links to other turtles show my out links shows agentset containing all the links ask turtle 1 show my out links shows an empty agentset myself myself self and myself are very different self i
10. tick do plots end to do plots plotxy ticks count turtles end By putting tick before do plots the plotting code gets the right value of the tick counter when it uses the ticks reporter Fractional ticks In most models the tick counter starts at O and goes up 1 at a time from integer to integer But it s also possible for the tick counter to take on in between floating point values To advance the tick counter by a fractional amount use the tick advance command This command takes a numeric input specifying how far to advance the tick counter A typical use of fractional ticks is to approximate continuous or curved motion See for example the GasLab models in the Models Library under Chemistry amp Physics These models calculate the exact time at which a future event is to occur then advance the tick counter to exactly that time View Updates The view in NetLogo lets you see the agents in your model on your computer s screen As your agents move and change you see them moving and changing in the view Of course you can t really see your agents directly The view is a picture that NetLogo paints showing you how your agents look at a particular instant Once that instant passes and your agents move and change some more that picture needs to be repainted to reflect the new state of the world Repainting the picture is called updating the view When does the view get updated This section discusses how NetLogo decid
11. 4 1 3 2 7 prints 1 2 3 4 Varying number of inputs Some commands and reporters involving lists and strings may take a varying number of inputs In these cases in order to pass them a number of inputs other than their default the primitive and its inputs must be surrounded by parentheses Here are some examples show list 1 2 gt 1 2 show list 1 2 3 4 Programming Guide 103 NetLogo 4 0 User Manual gt 1 2 3 4 show list gt Note that each of these special commands has a default number of inputs for which no parentheses are required The primitives which have this capability are list word sentence map and foreach Lists of agents Earlier we said that agentsets are always in random order a different random order every time If you need your agents to do something in a fixed order you need to make a list of the agents instead There are two primitives that help you do this sort and sort by Both sort and sort by can take an agentset as input The result is always a new list containing the same agents as the agentset did but in a particular order If you use sort on an agentset of turtles the result is a list of turtles sorted in ascending order by who number If you use sort on an agentset of patches the result is a list of patches sorted left to right top to bottom If you use sort on an agentset of links the result is a list of links sorted in ascending order first by endi then
12. 7 prints a number at least 0 but less than 3 7 for example 2 589444906014774 show random float 2 5 7 prints a number at least 0 but less than 2 5 for example 1 0897423196760796 random exponential random gamma random normal random poisson random exponential mean random gamma alpha lambda random normal mean standard deviation random poisson mean Reports an accordingly distributed random number with the mean and in the case of the normal distribution the standard deviation random exponential reports an exponentially distributed random floating point number random gamma reports a gamma distributed random floating point number as controlled by the floating point alpha and lambda parameters Both inputs must be greater than zero Note for results with a given mean and variance use inputs as follows alpha mean mean variance lambda 1 variance mean NetLogo Dictionary 311 NetLogo 4 0 User Manual random normal reports a normally distributed random floating point number random poisson reports a Poisson distributed random integer show random exponential 2 7 prints an exponentially distributed random floating 7 point number with a mean of 2 show random normal 10 1 5 2 7 prints a normally distributed random floating point 7 number with a mean of 10 1 and a standard deviation FE OF Da2 show random poisson 3 4 7 prints a Poisson distributed random integer with a mean of 3 4 random p
13. Example set heading 45 5 turtle is now facing northeast set heading heading 10 same effect as rt 10 hidden hidden me This is a built in turtle or link variable It holds a boolean true or false value indicating whether the turtle or link is currently hidden i e invisible You can set this variable to make a turtle or link disappear or reappear See also hide turtle show turtle hide link show link Example set hidden not hidden if turtle was showing it hides and if it was hiding 7 it reappears hide link hide link P The link makes itself invisible Note This command is equivalent to setting the link variable hidden to true See also_show link hide turtle ht NetLogo Dictionary 269 NetLogo 4 0 User Manual hide turtle The turtle makes itself invisible Note This command is equivalent to setting the turtle variable hidden to true See also_show turtle histogram histogram list Histograms the values in the given list Draws a histogram showing the frequency distribution of the values in the list The heights of the bars in the histogram represent the numbers of values in each subrange Before the histogram is drawn first any previous points drawn by the current plot pen are removed Any non numeric values in the list are ignored The histogram is drawn on the current plot using the current plot pen and pen color Use set plot x range to control the range of values t
14. NetLogo 4 0 User Manual NetLogo 4 0 User Manual Table of Contents What nn T 1 ESTOS ui A A eee vee ed 1 Copyright INTO MALO aia 3 Third party licenses iia iia 3 MersennelWiSterFaSt coiime linnien A eae det ees 3 LISO NL A A a 4 MR s AGA DIG asada dd 4 re 6 TE E tance Ra a E OE OC Tn E ee ens 4 SAOIDIAW 2 assa as ga aus nos E alas saga Ed A oe 4 MOVIGENCOGG fic cc IR RAR NPR RR RR O UR astace os 4 JpeglmagesToMovie errar rare eae rena EEE EEE EEE rasa rasa rasa rasa neaaeaaas 5 Fa EMMA RR RI RR RP SON ORI RAR UR RR RR URSO a RO 6 Mairix3D uia dia E eae AA A E A A aie a NETE 7 ASIM E erro as te ate alo ate ae pe Nene ra es Mime trees ad Nee lo ale ieee oct a o PO Do teo A O 7 EGO sir sito a if A UR dC RR RO AORE 8 Whats A asas siri RG ans oak tii 9 Version 4 0 September 2007 Lusoacaia notorias 9 Version 3 1 4 February 2007 dh ocooocococonononcnononononnnnnnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnonnnonnnnnnnenineniness 13 Version 3 1 April 2000 iii donada dao boda 14 Version 3 0 September 2000 laa Alis 14 Version 2 1 December 2004 ui bro 14 Version 2 0 2 August 2004 ooooococococoncconononononcnnncnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnininess 14 Version 2 0 December 2003 is 14 Version 1 3 June 200 Finn siri nina iara ii di ade nai dna 15 Version 12 March 2008 narinas iaa 15 Version 1 1 July 2002 nn ecra E 15 Version 1 0 Aprili2002 cnica a a a aaa
15. Note the empty list is written The empty string is written end end Used to conclude a procedure See to and to report end1 end1 This is a built in link variable It indicates the first endpoint turtle of a link For directed links this will always be the source for undirected links it will always be the turtle with the lower who number You cannot set end1 ert 2 ask turtle 0 create link to turtle 1 ask links show endl shows turtle 0 end2 end2 This is a built in link variable It indicates the second endpoint turtle of a link For directed links this will always be the destination for undirected links it will always be the turtle with the higher who number You cannot set end2 ert 2 ask turtle 1 NetLogo Dictionary 257 NetLogo 4 0 User Manual create link with turtle 0 ask links show end2 shows turtle 1 error message error message Reports a string describing the error that was suppressed by carefully This reporter can only be used in the second block of a carefully command See also carefully every every number commands Runs the given commands only if it s been more than number seconds since the last time this agent ran them in this context Otherwise the commands are skipped By itself every doesn t make commands run over and over again You need to use every inside a loop or inside a forever button if you want the commands run over and over again eve
16. SHOW Sete agua Danas ee as a Ae ae Soe O eal AS a USD E Da da O a eo Ea ad 325 SNOWSTUMIGS Ue siesta calda ada as ea tate las DE dd Da a ER da Gentes ad Nate 325 SHUT e AASP a e 325 ES IN Santi cado A A RR Ad Ea 326 ES IZ Gee a el oa e sea yd abe dardo aa AAA ee da eee 326 O a O 326 SOME A aa a DR A A Pa A 326 sprout sprout lt breeds gt rn nr rn rr 327 li AA OA A Pt hia Abe ee ies 327 a sis eset iiees acess a ieee ee ee ees qual dans eta 328 SAMP ti tidad 328 siandard devIA ON as cada 328 StartUp niet O 328 O tceiador E eh ea TEE 328 SUDICCL x5 EA dives ANN DE RIR LUC a rises A ea Ra ndo 329 SUBIISt SUDSTIING io depende rear b Tas tira E IERTA TUSD a Serena cada do 329 SUDIFACITNA CAMS ia A A as Aa 329 SU A AA A ibi 330 A e ino a a o E a e ade IAN ok nl ago et 330 NetLogo 4 0 User Manual Table of Contents NetLogo Dictionary xviii TAIN vie EEE E E DE RE nce ae A E E RD DOR 330 ICONO Suri a A ede dete a RR fe cate a 330 A EA NE AEA E AN PER AS 330 lE ala KAE A RA A dd raoba 330 TOK S ati nt a R NET TA 331 TN slic O E E 331 Sn T a E E A R A tes Dog O RD A anca nado 331 O E E A T E E EE 332 LOD E EEE TA E E E O 332 O r aE a a Lad paso eden td R hee A a LR A eet eee nae 332 TOW ANOS FARN EEEE E PERI EE E A A 333 ILENI ES URO KP A VAA EE EE AAT 333 UU gi 6 PPA E ENEE E E RT 333 wre Ser a eee a O aie De ace Dinda A tee DD TA iia Da ea 334 TUPI OS sim Be teeta ee ote A ok SR Saat dada 334
17. Second wouldn t it be nice to adjust the energy the turtles gain and lose as they eat grass and reproduce e Make a slider called energy from grass e Make another slider called birth energy e Then inside of cat grass make this change to Soat grass ask turtles if pcolor green set pcolor black set energy energy energy from grass ifelse show energy set label energy set label end e And inside of reproduce make this change to reproduce ask turtles if energy gt birth energy set energy energy birth energy hatch 1 set energy birth energy Finally what other slider could you add to vary how often grass grows back Are there rules you can add to the movement of the turtles or to the newly hatched turtles that happen only at certain times Try writing them What s next So now you have a simple model of an ecosystem Patches grow grass turtles wander eat the grass reproduce and die You have created an interface containing buttons sliders switches Tutorial 3 Procedures 65 NetLogo 4 0 User Manual monitors and plots You ve even written a series of procedures to give the turtles something to do That s where this tutorial leaves off If you d like to look at some more documentation about NetLogo the Interface Guide section of the manual walks you through every element of the NetLogo interface in order and explains its function For a detailed description and
18. 1 gt length 22 21 2 strings end show longest string hi there gt there count the number of occurrences of an item in a list to report occurrences x the list report reduce ifelse value 2 x 21 1 1 fput O the list end show occurrences 1 1 21312311451 gt 6 7 evaluate the polynomial with given coefficients at x to report evaluate polynomial coefficients x report reduce x 1 2 coefficients end 7 evaluate 3x 2 2x 1 at x 4 show evaluate polynomial 3 2 1 4 gt 57 remainder remainder number number2 Reports the remainder when number is divided by number2 This is equivalent to the following NetLogo code numberl int numberl number2 number2 show remainder 62 5 gt 2 show remainder 8 3 gt 2 See also_mod mod and remainder behave the same for positive numbers but differently for 314 NetLogo Dictionary NetLogo 4 0 User Manual negative numbers remove remove item list remove string1 string2 For a list reports a copy of list with all instances of item removed For strings reports a copy of string2 with all the appearances of string1 as a substring removed set mylist 2 7 4 7 Bob set mylist remove 7 mylist 5 mylist is now 2 4 Bob show remove to phototonic gt phonic remove duplicates remove duplicates list Reports a copy of list with all duplicate items removed The first of each item
19. 3 Open the Social Science folder 4 Click on the model called Party Sample Model Party 23 NetLogo 4 0 User Manual 5 Press the open button 6 Wait for the model to finish loading 7 optional Make the NetLogo window bigger so you can see everything 8 Press the setup button In the view you will see pink and blue lines with numbers 10 15 13 12 18 14 15 18 17 These lines represent mingling groups at a party Men are represented in blue women in pink The numbers are the total number of people in each group Do all the groups have about the same number of people Do all the groups have about the same number of each sex Let s say you are having a party and invited 150 people You are wondering how people will gather together Suppose 10 groups form at the party How do you think they will group Instead of asking 150 of your closest friends to gather and randomly group let s have the computer simulate this situation for us What to do 1 Press the go button Pressing go again will stop the model manually 2 Observe the movement of people until the model stops 3 Watch the plots to see what s happening in another way Now how many people are in each group Originally you may have thought 150 people splitting into 10 groups would result in about 15 people in each group From the model we see that people did not divide up evenly into the 10 groups instead some groups became ve
20. 4 4 4 e 4 e o new earth science models Continental Divide Climate Change new chemistry model Diprotic Acid new materials science model Solid Diffusion new mathematics models PANDA BEAR Solo Surface Walking 2D new network model Team Assembly new computer science models Hex Cell Aggregation Particle System Basic Particle System Fountain Particle System Waterfall Particle System Flame new game Planarity new social science models Language Change El Farol old El Farol model is now named El Farol Network Congestion new NIELS electromagnetism models Ohm s Law Series Circuit Parallel Circuit new Urban Suite curricular models new suite of Connected Chemistry curricular models new suite of BEAGLE Evolution curricular models models improved and promoted to verified Dice Stalagmite Autumn Conic Sections 2 Echo Rebellion Daisyworld Sound Machines Birthdays Bug Hunt Speeds Electrostatics other improved models Small Worlds bugfix most CA 1D models bugfix Star Fractal overhauled code Genetic Drift T Interact added optional walls Flocking smoother animation Planarity simpler code Mimicry simpler code GasLab Circular Particles cleaner code added plots acid base models simpler code new Code Examples Random Grid Walk Example Link Lattice Example Lattice Walking Turtles Example Link Walking Turtles Example Intersecting Links Example State Machine Example Breed Procedures
21. After you type a command it appears in the large scrolling box above the command line You can use Copy on the Edit menu in this area to copy commands and then paste them elsewhere such as the Procedures tab You can also access previous commands using the history popup menu which is the small downward pointing triangle to the right of where you type commands Click on the triangle and a menu of previously typed commands appears so you can pick one to use again Tip a quicker way to access previous commands is with the up and down arrow keys on your keyboard Clearing To clear the large scrolling area containing previous commands and output click clear in the top right corner To clear the history popup menu choose Clear History on that menu Arranging You can hide and show the command center using the Hide Command Center and Show Command Center items on the Tools menu To resize the command center drag the bar that separates it from the model interface Or click one of the little arrows on the right end of the bar to make the command center either very big or hidden altogether To switch between a vertical command center and a horizontal one click the button with the double headed arrow just to the left of Clear Interface Guide 79 NetLogo 4 0 User Manual Plots To show or hide a plot s pens legend click on the word Pens in the upper right corner of a plot If you move the mouse over the white area of a plot th
22. All three can also run procedures A procedure combines a series of NetLogo commands into a single new command that you define You will now learn to write procedures that make turtles move eat reproduce and die You will also learn how to make monitors sliders and plots The model we ll build is a simple ecosystem model not unlike parts of Wolf Sheep Predation from Tutorial 1 Making the setup button To start a new model select New from the File menu Then begin by creating a setup button e Click the Button icon in the toolbar at the top of the Interface tab e Click wherever you want the button to appear in the empty white area of the Interface tab e A dialog box for editing the button opens Type setup in the box labeled Commands e Press the OK button when you re done the dialog box closes Now you have a setup button Pressing the button runs a procedure called setup A procedure is a sequence of NetLogo commands that we assign a new name We haven t defined that procedure yet we will soon Because the button refers to a procedure that doesn t exist yet the button turns red Tutorial 3 Procedures 47 NetLogo 4 0 User Manual interface Information Procedures P 3 M view updates abe Button M L continuous ry Edit Delete Add normal speed a a a Wa 4 ticks 0 Ea If you want to see the actual error message click the button Now we ll create the setup procedu
23. An example is the GNU libgcj based runtime on Linux which comes preinstalled on some Linux distributions NetLogo does not work with this runtime We recommend the Sun or IBM Java runtimes when using NetLogo on Linux Can I run NetLogo from the command line without the GUI Yes The easiest way is to set up your model run as a BehaviorSpace experiment No additional programming is required See the BehaviorSpace section of the User Manual for details Another option is to use our Controlling API Some light Java programming is required See the Controlling section of the User Manual for details and sample code Does NetLogo take advantage of multiple processors cores Not for a single model run no The NetLogo engine is single threaded and we expect it to remain that way We don t have any plans to make it possible to split a single model run across multiple processors or multiple computers One way to take advantage of multiple processors or multi core processors to do multiple model runs concurrently by running more than one instance of NetLogo simultaneously each in its own Java virtual machine e To run more than one copy of the full NetLogo application at once see this answer for instructions e You can also run models from the command line using BehaviorSpace or the Controlling API and start up as many separate headless NetLogo processes simultaneously as you want In a future version of NetLogo we hope to improve the
24. But if you recall the original model contained one red car amongst a group of blue cars Let s look at how to change only one car s color e Press setup to get the red car to reappear e If you are on a Macintosh hold down the Control key and click on the red car On other operating systems click on the red car with the right mouse button e f there is another turtle close to the red turtle you ll see more than one turtle listed at the bottom of the menu Move your mouse over the turtle selections notice when your mouse highlights a turtle menu item that turtle is highlighted in the view Select inspect turtle from the sub menu for the red turtle A turtle monitor for that car will appear 42 Tutorial 2 Commands NetLogo 4 0 User Manual Taking a closer look at this turtle monitor we can see all of the variables that belong to the red car A variable is a place that holds a value that can be changed Remember when it was mentioned that all colors are represented in the computer as numbers The same is true for the agents For example every turtle has an ID number we call its who number Let s take a closer look at the turtle monitor What is this turtle s who number What color is this turtle What shape is this turtle This turtle monitor is showing a turtle who that has a who number of 0 a color of 15 red see above chart and the shape of a car There are two other ways to open a tu
25. For more information on NetLogo extensions see the Extensions Guide Models saved as applets using Save as Applet on NetLogo s File menu cannot use the Gogo extension since applets can t use extensions that require additional extra jars Also unsigned applets aren t allowed to access external devices anyway For examples that use the GoGo extension see the GoGo section under Code Examples in NetLogo s Models Library Primitives ogo output port reverse gogo outout port_ that this way gogo ping gogo sensor gogo set output port power gogo talk to output ports gogo close gogo close Close the connection to the GoGo Board See also gogo open and gogo open gogo open 206 GoGo Extension NetLogo 4 0 User Manual gogo open port name Open a connection to the GoGo Board connected to serial port named port name See gogo ports for more information about port names If the GoGo Board is not responding or you attempt to open a port without a GoGo Board connected to it an error will be generated Example gogo open COM1 See also gogo open and gogo close gogo open gogo open Reports true if there is a connection to a GoGo board open Reports false otherwise gogo ports gogo ports Reports a list of serial port names which a GoGo Board may be connected to On certain computers you might get a list of two or three different serial ports In that case try to open each of them until the connection i
26. Here is one final example that shows how to run an experiment setup which is stored in a separate XML file instead of in the model file java server Xmsl16M Xmx1024M cp NetLogo jar org nlogo headless HeadlessWorkspace model Fire nlogo setup file fire setups xml xperiment experiment3 If the XML file contains more than one experiment setup it is necessary to use the experiment argument to specify the name of the setup to use The next section has information on how to create standalone experiment setup files using XML Setting up experiments in XML We don t yet have detailed documentation on authoring experiment setups in XML but if you already have some familiarity with XML then the following pointers may be enough to get you BehaviorSpace Guide 159 NetLogo 4 0 User Manual started The structure of BehaviorSpace experiment setups in XML is determined by a Document Type Definition DTD file The DTD is stored in NetLogo jar as system behaviorspace dtd JAR files are also zip files so you can extract the DTD from the JAR using Java s jar utility or with any program that understands zip format The easiest way to learn what setups look like in XML though is to author a few of them in BehaviorSpace s GUI save the model and then examine the resulting nlogo file in a text editor The experiment setups are stored towards the end of the nlogo file in a section that begins and ends with a experiments
27. How do take the negative Of a NUMber occccccnnnnoconcncnccccononononnncnnnncnnnnnnnnnnonnnncncnanannns 230 My turtle moved forward 1 but it s still on the same patch Why2 230 How do keep my turtles on patch Centers ccconnonococccnncccnonnnononnccnnnnncnnnnnnnnnnnnnncnnnnnnnnns 231 patch ahead 1 is reporting the same patch my turtle is already standing on Why 231 How do give my turtles vision ccssscccecceesssseeeeeeeeeeeeeeeseeneeeeeeeeeessseeneaeeeeeeeseesee 231 Can agents sense what s in the drawing layer occconococccnccccccnonoooonncnnncccnnnannnnncnnnnnnnns 232 I m getting numbers like 0 10000000004 and 0 799999999999 instead of 0 1 and DES IIA or E CT Adu ES Muasaaue 232 The documentation says that random float 1 might return O but will never return 1 What if want 1 to be included eretas naninanono 232 How can keep two turtles from occupying the same patChB oooccccccccnonoccooncncncncnanannns 232 How can find out if a turtle is dead errar nana canonanananes 232 Does NetLogo have arraySP oooooccccccccnononononnnncccnnnnanononnnnnnnnnnnnnnnnnnrnnnnrnnnnnnnnnnrnnnnnncnannnnos 232 Does NetLogo have hash tables or associative arrays 2 233 How can use different patch neighborhoods circular Von Neumann Moore AC Mea ana chou te tein dl dama CORA a a o ch Marea SR aly a is a pa ad 233 How can convert an agentset to a list of agents or vice versa
28. In NetLogo 4 0 these primitives have been replaced with new primitives called turtle set and patch set that are much more flexible and powerful 1ink set exists as well See the entries for these primitives in the NetLogo Dictionary Models that use the old turtles from and patches from will need to be altered by hand to use the new primitives RGB Colors In NetLogo 3 1 RGB and HSB colors could be approximated as NetLogo colors using the rgb and hsb primitives These have been renamed to approximate rgb and approximate hsb and now expect inputs in the range 0 255 not 0 1 Transition Guide 141 NetLogo 4 0 User Manual The full RGB spectrum is now available in NetLogo so it may no longer be necessary to use these primitives at all You can set any color variable to a three item RGB list with values in the 0 255 range and get that exact color See the_Color section of the Programming Guide for details Tie In previous versions __ tie was provided as an experimental feature As of NetLogo 4 0 links have a tie mode variable which can be set to none free or fixed In 4 0 tie is nowa link only primitive This means that to tie two turtle 1 to turtle O you write ask turtle O create link to turtle 1 tie See the_Tie section of the programming guide for details HubNet Clients A HubNet activity s client interface is no longer stored in a separate model file To import a client from an old model select File gt Import
29. It takes an input list and a block of commands like this foreach 2 4 6 Dert show word created turtles gt created 2 turtles gt created 4 turtles gt created 6 turtles In the block the variable 2 holds the current value from the input list Here are some more examples of foreach foreach 1 2 3 ask turtles fd turtles move forward 6 patches foreach true false true true ask turtles if fd 1 7 turtles move forward 3 patches map is similar to foreach but it is a reporter It takes an input list and another reporter Note that unlike foreach the reporter comes first like this show map round 1 2 2 2 2 7 7 prints 1 2 3 map reports a list containing the results of applying the reporter to each item in the input list Again use to refer to the current item in the list Here is another example of map show map lt 0 1 1 3 4 2 10 5 prints false true false false true true foreach and map won t necessarily be useful in every situation in which you want to operate on an entire list In some situations you may need to use some other technique such as a loop using repeat Or while or a recursive procedure The_sort by primitive uses a similar syntax to map and foreach except that since the reporter needs to compare two objects the two special variables 1 and 2 are used in place of Here is an example of sort by show sort by 1 lt 2
30. NetLogo 4 0 User Manual Note The technical details on this are as follows In order for the client to detect the server multicast routing must be available between them Not all networks support multicast routing In particular networks that use the IPsec protocol typically do not support multicast The IPsec protocol is used on many virtual private networks VPNs When a participant tries to connect to an activity nothing happens the client appears to hang or gives an error saying that no server was found If your computer or network has a firewall it may be impeding the HubNet server from communicating Make sure that your computer and network are not blocking ports used by the HubNet server ports 9173 9180 The view on the HubNet client is grey e Verify that the Mirror 2D view on clients checkbox in the HubNet Control Center is selected e Make sure that the display switch in the model is on e If you have made changes to the size of the view on the server you may need to press the Reset button in the Control Center to ensure the clients get the new size There is no view on the HubNet client Some activities don t have a view on the client If you want to add a view simply select HubNet Client Editor from the Tools Menu and add a view like any other widget Make sure to press the Reset button before having clients log in can t quit a HubNet client You will have to force the client to quit On OS X force quit the applica
31. Note the use of other to exclude the calling agent This is common Once you have created an agentset here are some simple things you can do e Use ask to make the agents in the agentset do something e Use any to see if the agentset is empty e Use ali to see if every agent in an agentset satisfies a condition e Use count to find out exactly how many agents are in the set And here are some more complex things you can do e Pick a random agent from the set using one of For example we can make a randomly chosen turtle turn green ask one of turtles set color green Or tell a randomly chosen patch to sprout a new turtle ask one of patches sprout 1 e Use the max one of Or min one of reporters to find out which agent is the most or least along some scale For example to remove the richest turtle you could say 96 Programming Guide NetLogo 4 0 User Manual ask max one of turtles sum assets die e Make a histogram of the agentset using the histogram command in combination with of e Use of to make a list of values one for each agent in the agentset Then use one of NetLogo s list primitives to do something with the list See the Lists section_ below For example to find out how rich turtles are on the average you could say show mean sum assets of turtles e Use turtle set patch set and link set reporters to make new agentsets by gathering together agents from a variety of possible sources e Check whether two a
32. Reports the statistical median of the numeric items of the given list Ignores non numeric items The median is the item that would be in the middle if all the items were arranged in order If two items would be in the middle the median is the average of the two show median xcor of turtles 7 prints the median of all the turtles x coordinates member member value list member string1 string2 member agent agentset For a list reports true if the given value appears in the given list otherwise reports false For a string reports true or false depending on whether string1 appears anywhere inside string2 as a substring For an agentset reports true if the given agent is appears in the given agentset otherwise reports false show member 2 1 2 3 gt true show member 4 1 2 3 gt false show member bat abate gt Crue show member turtle 0 turtles gt true show member turtle 0 patches gt false See also_position 290 NetLogo Dictionary NetLogo 4 0 User Manual min min list Reports the minimum number value in the list It ignores other types of items show min xcor of turtles 7 prints the lowest x coordinate of all the turtles min one of min one of agentset reporter Reports a random agent in the agentset that reports the lowest value for the given reporter If there is a tie this command reports one random agent that meets the condition If you want all such agents use wit
33. That code is run when you press the button A button may be either a once button or a forever button You can control this by editing the button and checking or unchecking the Forever checkbox Once buttons run their code once then stop and pop back up Forever buttons keep running their code over and over again until either the code hits the stop command or you press the button again to stop it If you stop the button the code doesn t get interrupted The button waits until the code has finished then pops up Normally a button is labeled with the code that it runs For example a button that says go on it usually contains the code go which means run the go procedure Procedures are defined in the Procedures tab see below But you can also edit a button and enter a display name for the button which is a text that appears on the button instead of the code You might use this feature if you think the actual code would be confusing to your users Programming Guide 99 NetLogo 4 0 User Manual When you put code in a button you must also specify which agents you want to run that code You can choose to have the observer run the code or all turtles or all patches or all links If you want the code to be run by only some turtles or some patches you could make an observer button and then have the observer use the ask command to ask only some of the turtles or patches to do something When you edit a button you have the
34. appropriate turtle to die to remove student ask students with user id hubnet message source die end All other messages are interface elements identified by the hubnet message t ag which is the name that appears in the client interface Every time an interface element changes a message is sent to the server Unless you store the state of the values currently displayed in the client interface will not be accessible in other parts of the model That s why we ve declared a student s own variable for every interface element that has a state sliders switches etc When we receive the message from the client we set the turtle variable to the content of the message 1f hubnet message tag step size ask students with user id hubnet message source set step size hubnet message Since buttons don t have any associated data there is generally no associated turtle variable instead they indicate an action taken by the client just as with a regular button there is often procedure associated with each button that you call whenever you receive a message indicating the button has been pressed Though itis certainly not required the procedure is often a turtle procedure that is something that the student turtle associated with the message source can execute if command move left set heading 270 fol 1 HubNet Authoring Guide 171 NetLogo 4 0 User Manual Sending messages to clients As mentioned earli
35. ask turtle 0 ask my links die 136 Transition Guide NetLogo 4 0 User Manual Several of the layout commands have slightly different inputs the first two inputs are generally a turtle agentset and a link agentset to perform the layout on See the dictionary entries for details layout spring layout magspring layout radial layout tutte You may also need to rearrange the declaration of turtles own variables since links were once actually turtles Any variables that apply to links should be moved into a 1inks own block Since links are no longer turtles they no longer have the built in turtle variables though some of the link variables are the same such as color and label If you formerly used the location of link turtles you will now need to calculate the midpoint of the link This is fairly simple in a non wrapping world to report link xcor report mean xcor of both ends end to report link ycor report mean ycor of both ends end itis a little bit trickier in a wrapping world but still fairly straight forward to report link xcor let other guy end2 let x 0 ask endl hatch 1 face other guy fd distance other guy of myself 2 set x xcor die report x end and similarly for ycor If you used either the size or heading of the link turtles you can use the reporters Link length and link heading instead New of syntax We have replaced three different language constructs of with hyphe
36. contact us we may be able to help you do you what you want Please do not hesitate to contact us at feedback ccl northwestern edu with questions as we may be able to find a workaround or provide additional guidance where our documentation is thin 182 Controlling Guide Mathematica Link What is it The NetLogo Mathematica link provides modelers with an easy to use real time link between NetLogo and Mathematica Together these tools can provide users with a highly interactive self documenting work flow that neither can provide alone Mathematica includes many of the tools that agent based modelers rely on throughout the research process advanced import capabilities statistical functions data visualization and document creation With the NetLogo Mathematica link you can run all of these tools side by side with NetLogo Because all Mathematica documents or notebooks contain comments code images annotations and interactive objects the integration of NetLogo and Mathematica provides a more complete solution for complex model exploration for students and researchers alike The basic functionality of the link is much like the NetLogo Controlling API you can load models execute commands and report back data from NetLogo Unlike the Controlling API which is based on Java all interactions with the link are interpreted making it ideal not only for rapidly designing custom BehaviorSpace like experiments but also as a companion to
37. foreach 60 62 64 65 67 69 71 72 sound start note XYLOPHONE 65 wait 0 2 sound stop note XYLOPHONE sound stop note sound stop note instrument keynumber Stops a note 7 stop a violin note at middle C sound stop note VIOLIN 60 Sound Extension 201 NetLogo 4 0 User Manual sound stop instrument sound stop instrument instrument Stops all notes of an instrument 7 stop all cello notes sound stop instrument CELLO sound stop music sound stop music Stops all notes Sound names Drums 35 Acoustic Bass Drum 59 Ride Cymbal 2 36 Bass Drum 1 60 Hi Bongo 37 Side Stick 61 Low Bongo 38 Acoustic Snare 62 Mute Hi Conga 39 Hand Clap 63 Open Hi Conga 40 Electric Snare 64 Low Conga 41 Low Floor Tom 65 Hi Timbale 42 Closed Hi Hat 66 Low Timbale 43 Hi Floor Tom 67 Hi Agogo 44 Pedal Hi Hat 68 Low Agogo 45 Low Tom 69 Cabasa 47 Open Hi Hat 70 Maracas 47 Low Mid Tom 71 Short Whistle 48 Hi Mid Tom 72 Long Whistle 49 Crash Cymbal 1 73 Short Guiro 50 Hi Tom 74 Long Guiro 51 Ride Cymbal 1 75 Claves 52 Chinese Cymbal 76 Hi Wood Block 53 Ride Bell 77 Low Wood Block 54 Tambourine 78 Mute Cuica 55 Splash Cymbal 79 Open Cuica 56 Cowbell 80 Mute Triangle 57 Crash Cymbal 2 81 Open Triangle 58 Vibraslap Instruments Piano Reed 1 Acoustic Grand Piano 65 Soprano Sax 2 Bright Acoustic Piano 66 Alto Sax 3 Electric Grand P
38. gt lt gt but first but last empty first is string item last length member position remove remove item read from string replace item reverse substring word Mathematical log max mean median min mod modes new seed pi precision random random exponential random float random gamma random normal random poisson random seed remainder round sin sqrt standard deviation subtract headings sum tan variance Plotting autoplot auto plot off auto plot on clear all plots clear plot create temporary plot pen export plot export all plots histogram plot plot name plot pen exists plot pen down lot pen reset plot pen up plot x max plot x min plot y max plot y min plotxy set current plot set current plot pen set histogram num bars set plot pen color set plot pen interval set plot pen mode set plot x range set plot y range Links both ends clear links create lt breed gt from create lt breeds gt from create lt breed gt to create lt breeds gt to create lt breed gt with create lt breeds gt with create link from create links from create link to create links to create link with create links with in lt breed gt neighbor in lt breed gt neighbors in lt breed gt from in link neighbor in link neighbors in link from is directed link is link is undirected link layout circle layout magspring layout radial layout spring layout tutte lt breed gt neighbor lt breed gt neighbor
39. info gt lt category gt or you can simply remove the entire reference to the category from the configuration file as it is not serving any other purpose Advanced Configuration This is only a basic introduction to configuration files for logging in NetLogo There are many more configuration options available through the log4j framework See the log4j documentation 178 Logging Controlling Guide NetLogo can be invoked from another Java program and controlled by that program For example you might want to call NetLogo from a small program that does something simple like automate a series of model runs This section of the User Manual introduces this facility for Java programmers We ll assume that you know the Java language and related tools and practices Note The controlling facility is considered experimental It is likely to continue to change and grow Code you write now that uses it may need changes in order to continue to work in future NetLogo versions e Note on memory usage e Example with GUI e Example headless e BehaviorSpace e Other Options e Conclusion The NetLogo API Specification contains further details Note on memory usage In all of the examples below when invoking Java to run them you probably don t want to accept the default heap size settings Most Java VM s have a very small initial heap size and a small maximum heap size too When you run the NetLogo application it uses an initial
40. keep them straight Vary variables as follows This is where you specify which settings you want varied and what values you want them to take Variables can include sliders switches choosers and any global variables in your model Variables can also include max pxcor min pxcor max pycor and min pycor world width world height and random seed These are not strictly speaking variables but BehaviorSpace lets you vary them as if they were Varying the world dimensions lets you explore the effect of world size upon your model Since setting world width and wor1d height does not necessarily define the bounds of the world how they are varied depends on the location of the origin If the origin is centered BehaviorSpace will keep it centered so the values world width or world height must be odd If one of the bounds is at zero that bound will be kept at zero and the other bound will move for example if you start with a world with min pxcor 0 max pxcor 10 and you vary world width like this rom lo zwi adtht ial ik aL J 154 BehaviorSpace Guide NetLogo 4 0 User Manual min pxcor will stay at zero and max pxcor will set to 11 12 and 13 for each of the runs If neither of these conditions are true the origin is not centered nor at the edge of the world you cannot vary world height or world width directly but you should vary max pxcor max pycor min pxcor and min pycor instead Varying random seed lets you repeat runs by using
41. reports an empty list show modes 1 2 2 3 4 gt 2 show modes 1 2 2 3 3 4 gt 2 3 show modes 1 2 3 1 2 3 2 3 4 gt 1 2 3 show modes pxcor of turtles 7 shows which columns of patches have the most turtles on them mouse down mouse down Reports true if the mouse button is down false otherwise Note If the mouse pointer is outside of the current view mouse down will always report false mouse inside mouse inside Reports true if the mouse pointer is inside the current view false otherwise mouse patch mouse patch Reports a patch if the mouse pointer is pointing to one otherwise reports nobody 292 NetLogo Dictionary NetLogo 4 0 User Manual mouse xcor mouse ycor mouse xcor mouse ycor Reports the x or y coordinate of the mouse in the 2D view The value is in terms of turtle coordinates so it might not be an integer If you want patch coordinates use round mouse xcor and round mouse ycor Note If the mouse is outside of the 2D view reports the value from the last time it was inside 77 to make the mouse draw in red if mouse down ask patch mouse xcor mouse ycor set pcolor red move to move to agent The turtle sets its x and y coordinates to be the same as the given agent s If that agent is a patch the effect is to move the turtle to the center of that patch move to turtle 5 7 turtle moves to same point as turtle 5 move to one
42. the experiments that you do with it can be reproduced by others Here s how it works NetLogo s random number generator can be started with a certain seed value which can be any integer Once the generator has been seeded with the random seed command it always generates the same sequence of random numbers from then on For example if you run these commands random seed 137 show random 100 show random 100 show random 100 Programming Guide 107 NetLogo 4 0 User Manual You will always get the numbers 95 7 and 54 in that order Note however that you re only guaranteed to get those same numbers if you re using the same version of NetLogo Sometimes when we make a new version of NetLogo the random number generator changes Presently we use a generator known as the Mersenne Twister To create a number suitable for seeding the random number generator use the new seed reporter new seed Creates a seed evenly distributed over the space of possible seeds based on the current date and time It never reports the same seed twice in a row Code Example Random Seed Example If you don t set the random seed yourself NetLogo sets it to a value based on the current date and time There is no way to find out what random seed it chose so if you want your model run to be reproducible you must set the random seed yourself ahead of time The NetLogo primitives with random in their names random random float and so on aren t the onl
43. turtles at ZAS 334 turtles here lt breed gt NBlB occcooccccnoncncnccnnnnnonnnnnnnnnnn nano nonnnn nano nnn cnn nan nn nan nn nn rn n nara naaa 334 turiles on lt DFECAS gt OM tar dad lb da 335 turiles own lt DIreedS gt QWO occccncccnnonononcnnnnanononcnnnnono nan nononano narra nn nnn narran narrar rn narran 335 a a N 336 IS IR A o ana atte rh doh ae ce aN 336 Lindirecied link breed unica id O diia 336 A EA DRDS E RR RN DRI RS RR asa A E oN O RR ERR 337 TA A DEAR ER 337 USE Vi A A DRE at 338 US lia ica 338 USC li o ed e A e Na EN 338 USC PUE candidata 338 User mMessage cuina da 339 BEE E EE te tel ea eed tees te E al een ee fee kao A 339 SENOS OO a a E SM RUA ai ab E TA pa 339 Nei RU ana ia E DO RA A Ee RA a 339 VANANCO A dA SEL PDT A dvaetove Po ios da 339 O ada eh ba shane do eta codec Meus da ie qi AGR cee A da a a q a DT reat a ta ate a 340 CAVALO os A A RAD A dr Bd RA A ARE SA Ae A ASS A oie AR 340 WTC US ANPR ARS AR RR RR A A ARRUDA RR O RR atic She wath aed 340 WaAICHEING PAGAR AR tdi UNR RS ASR RAR RS 340 IES A a ea Re TD aq AR ECA aa e A e eRe 340 WIN OSS Es ssa iso E ad ee O RUE ida E O aaa q OE E ci REM oe DO Bie aba do 341 PA PANA loot A eh AE EN NR RR FREAR ROO ED SR RR 341 lt breed gt with link with resetar areas er tarte tanta 341 WIN MA as A cre rs A os creu Oe e A Lara 342 WiLh I A AE A ad aii le A O A Oi ee A se Se da dd 342 wilh local randomhessS sega seia sita toa le iea doses dio Ta Sela AE
44. you need to download the Java browser plugin from http www java com en download windows manual jsp e If you re on Mac OS X you need OS X 10 2 6 or higher If you re on OS X 10 2 you also need Java 1 4 1 Update 1 which is available through Software Update OS X 10 3 and higher already has the right Java You must also use a web browser that supports Java 1 4 Internet Explorer does not work Safari does Applets 145 NetLogo 4 0 User Manual e If you re on Windows 95 MacOS 8 or MacOS 9 running models over the web is no longer supported you must download the NetLogo 1 3 1 application and run the models that way instead e If you re on Linux or another Unix you will need version 1 4 1 or higher of the Sun Java Runtime Environment It is available for download at http www java com Check your browser s home page for information about installing the Java plugin If you think you have the right browser and plugin but it still doesn t work check your browser s preferences to make sure that Java is enabled The following web site may be helpful for figuring out what Java you have and getting the right version running htip www javatester org Increasing the available memory Some NetLogo applets may require more memory than the browser normally makes available This may happen if you have large numbers of agents On Windows you can increase the available memory heap space in the Java Control Panel s applet runtime settings
45. 2 7 5 Bob 3 0 2 set mylist replace item 2 mylist 10 mylist is now 2 7 10 Bob 3 0 2 The replace item reporter takes three inputs The first input specifies which item in the list is to be changed 0 means the first item 1 means the second item and so forth To add an item say 42 to the end of a list use the 1put reporter fput adds an item to the beginning of a list set mylist lput 42 mylist mylist is now 2 7 10 Bob 3 0 2 42 But what if you changed your mind The but 1ast b1 for short reporter reports all the list items but the last set mylist but last mylist mylist is now 2 7 10 Bob 3 0 2 Suppose you want to get rid of item 0 the 2 at the beginning of the list set mylist but first mylist mylist is now 7 10 Bob 3 0 2 Suppose you wanted to change the third item that s nested inside item 3 from 2 to 9 The key is to realize that the name that can be used to call the nested list 3 0 2 is item 3 mylist Then the replace item reporter can be nested to change the list within a list The parentheses are added for clarity set mylist replace item 3 mylist replace item 2 item 3 mylist 9 mylist is now 7 10 Bob 3 0 9 Iterating over lists If you want to do some operation on each item in a list in turn the oreach command and the map reporter may be helpful 102 Programming Guide NetLogo 4 0 User Manual foreach is used to run a command or commands on each item in a list
46. 22 cece wuss RR POSEIDON aus RR RES theese 278 MAIS A ce A A pe Ee ea A Oo i ae aie SAAN ed O ae 278 is link set is list is number is patch is patch set is string is turtle is turtle set is undirected link ccc ceeeeeeesee ee eeesueeeeceeueeeseeeueeaeueeesaaseeenes 279 DOI o RS ARS A A O A AE 280 ras catia tine ket sheet PE ten ume ATEU ths ct tee da ACAO dd A 280 JUNTA eases Nicos gua SS Pa DS A A RD nine 280 A E nba casar TRA 280 ABES dogs oa tin o eich eat Da th aati RAN CNA ahs etn ees 280 JADGISCOlO bass A O a Ea a 281 ASIA ted R tetas a Odea SP ne Se ce ea each hes coc Ne ony DE Ge a sete 281 IAYQUI CIFCIO a lie 281 AYUNAS prige e a ii 282 ENT O 283 EA O 283 layoUt tU lean dai 284 Mi a A A A RAS RPA OR eats 285 A AN NO 285 A e a RM oes o e A a a tae ate toe at DO qa 285 Mi ad A 285 INN Mr 286 MS A O 286 IAKSSG Le A A AA a A e o eT A A At 286 A a na 286 links own lt liNk bDreedSs gt QWNO cocooccccnccccnocononcccnnncononcnnonccnnnnnoconannnnn nono ncnnoncnno nana na arara 287 MS a lanes Bea dis T e qd da E a a a e ac aaa 287 A A de EE q A qe a RD dra oe Mie aa ae 287 DO Oia Sa Se 287 O O PRE A 288 AID JD EE eb e RR RR RR RP A dues idols E DROP RR RE RSA AE 288 NA acto A A qdo MATION oe Bas RD A OA i he rd ea OO A A A BS ag DD GA ae 288 RIA GEE A A A 288 A eet Bae a a Se eee ee Ae Sa 289 MEVEN A Ms ie eae oe see tee eas ee oe fete e Do als es du data DE A aa a Ea al 289 max pxXCOr
47. 4 Re open any files that the model had opened with the file open command 5 If you want press Go button to continue running the model from the point where it left off If you wish to import a file from a location other than the model s location you may include the full path to the file you wish to import See export world for an example 276 NetLogo Dictionary NetLogo 4 0 User Manual in cone agentset in cone distance angle This reporter lets you give a turtle a cone of vision in front of itself The cone is defined by the two inputs the vision distance radius and the viewing angle The viewing angle may range from 0 to 360 and is centered around the turtle s current heading If the angle is 360 then in cone is equivalent to in radius in cone reports an agentset that includes only those agents from the original agentset that fall in the cone This can include the calling agent itself The distance to a patch is measured from the center of the patch ask turtles ask patches in cone 3 60 set pcolor red each turtle makes a red splotch of patches in a 60 degree cone of radius 3 ahead of itself in lt breed gt neighbor in link neighbor in lt breed gt neighbor agent in link neighbor turtle Reports true if there is a directed link going from turtle to the caller crt 2 ask turtle 0 create link to turtle 1 show in link neighbor turtle 1 prints false show out link neighbor turtle 1 p
48. 4 6 8 10 show item 2 mylist gt 6 show item 3 my shoe gt g jump jump number The turtle moves forward by number units all at once rather than one step at a time as with the forward command If the turtle cannot jump number units because it is not permitted by the current topology the turtle does not move at all See also_forward can move L label label ae This is a built in turtle or link variable It may hold a value of any type The turtle or link appears in the view with the given value attached to it as text You can set this variable to add change or remove a turtle or link s label See also label color plabel plabel color Example ask turtles set label who all the turtles now are labeled with their 280 NetLogo Dictionary NetLogo 4 0 User Manual 7 who numbers ask turtles set label 7 all turtles now are not labeled label color label color ae This is a built in turtle or link variable It holds a number greater than or equal to O and less than 140 This number determines what color the turtle or link s label appears in if it has a label You can set this variable to change the color of a turtle or link s label See also label plabel plabel color Example ask turtles set label color red all the turtles now have red labels last last list last string On a list reports the last item in the list On a string reports a one
49. ERAS AA DE 130 COMO A o old cay iga Ss cia aan s Isa ISS agido a Asia es osso 131 SIMUGTURG 2 tia 131 Commands and DOS Rn EE aA dard nacre tte tow bade aero 131 Compared to other LOGOS a teus aa RAS A A a UG fa 132 Transition GuUide cccoooncccccnonacccnnnnanocononanaconnanancnona nan rnonn naar conan nn rr nana na rana na nara nana r conan a rona nana nnn 135 Since NODOS di A A io 135 Who DUMDEITINQ EEEE E E rr 135 Turtle creation randomized VS ONerO O dennccconncccncccnnoncnoncnnnannnnnanano nono nan cn non ncn narra nannannn 135 Addind Sstings OO Si NAAA e 135 NAAA AA ut RS 136 New Ol SIMA 5 di tala 137 SU lo sio 138 TOK CONE o a tico 138 View update modes a e e a ARA eaaa ae ia iaeia 139 Speed A E E E E A E E AO 140 Numbers anat ao 141 AQentset BUIldINA ii AA ia 141 RGB Colors 2 dia tae Tals 141 DG Seen Re nD nr q O to a a Sais A a Doda a Pee nas TR 142 HubNet Clients ssa nessa eet Seceeee teed os 142 Pertormance O L SIS iii E a td Da bi 142 Since Netlog Dira ao 142 AQENISOIS ni renais arara A a 142 WHADDING sacaron inter 142 No 0 23 iiss Sedaris ta RR NR adie deed AD ASAS RAE SR 145 Making and Displaying Applets occcccccccccnncnnncnnnonnnonnnnnonononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnniss 145 Java Requirements miii cial ea eevele 145 Getting the right Yesica 145 Increasing the available MeMoty occcccccncccnccnccinicenineninnninnnineninnnnnnnnrnnnr rre 146 EXTENSIONS A ala Aree a oe ee e
50. Manual file delete file delete string Deletes the file specified as string string must be an existing file with writable permission by the user Also the file cannot be open Use the command file close to close an opened file before deletion Note that the string can either be a file name or an absolute file path If it is a file name it looks in whatever the current directory is This can be changed using the command set current directory It is defaulted to the model s directory file exists file exists string Reports true if string is the name of an existing file on the system Otherwise it reports false Note that the string can either be a file name or an absolute file path If it is a file name it looks in whatever the current directory is This can be changed using the command set current directory It defaults to to the model s directory file flush file flush Forces file updates to be written to disk When you use file write or other output commands the values may not be immediately written to disk This improves the performance of the file output commands Closing a file ensures that all output is written to disk Sometimes you need to ensure that data is written to disk without closing the file For example you could be using a file to communicate with another program on your machine and want the other program to be able to see the output immediately file open file open string This command will interpret stri
51. See also output write X xcor xcor This is a built in turtle variable It holds the current x coordinate of the turtle You can set this variable to change the turtle s location This variable is always greater than or equal to min pxcor 0 5 and strictly less than max pxcor 0 5 See also_setxy ycor pxcor pycor 344 NetLogo Dictionary NetLogo 4 0 User Manual xor boolean xor boolean2 Reports true if either boolean or boolean2 is true but not when both are true if pxcor gt 0 xor pycor gt 0 set pcolor blue 7 upper left and lower right quadrants turn blue Y ycor ycor This is a built in turtle variable It holds the current y coordinate of the turtle You can set this variable to change the turtle s location This variable is always greater than or equal to min pycor 0 5 and strictly less than max pycor 0 5 See also setxy _xcor Oxcor pycor 2 Dat Ng A aes By 1 22 93 5 These are special local variables They hold the current inputs to a reporter or command block for certain primitives for example the current item of a list being visited by foreach or map is always equivalent to 21 You may not set these variables and you may not use them except with certain primitives currently foreach map reduce filter sort by and n values See those entries for example usage NetLogo Dictionary 345 NetLogo 4 0 User Manual 346 NetLogo Dictionary
52. Structure A program consists of optional declarations globals breed turtles own patches own lt BREED gt own in any order followed by zero or more procedure definitions Multiple breeds may be declared with separate breed declarations the other declarations may appear once only Every procedure definition begins with to or to report the procedure name and an optional bracketed list of input names Every procedure definition ends with end In between are zero or more commands Commands and reporters Commands take zero or more inputs the inputs are reporters which may also take zero or more inputs No punctuation separates or terminates commands no punctuation separates inputs Identifiers must be separated by whitespace or by parentheses or square brackets So for example a b is a single identifier but a b c d e contains five identifiers All commands are prefix All user defined reporters are prefix Most primitive reporters are prefix but some arithmetic operators boolean operators and some agentset operators like with and in points are infix All commands and reporters both primitive and user defined take a fixed number of inputs by default That s why the language can be parsed though there is no punctuation to separate or terminate commands and or inputs Some primitives are variadic that is may optionally take a different number of inputs than the default parentheses are used to indicate this
53. Sun Copyright Information 5 NetLogo 4 0 User Manual This software is provided AS IS without a warranty of any kind ALL EXPRESS OR IMPLIED CONDITIONS REPRESENTATIONS AND WARRANTIES INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE OR NON INFRINGEMENT ARE HEREBY EXCLUDED SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING MODIFYING OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE PROFIT OR DATA OR FOR DIRECT INDIRECT SPECIAL CONSEQUENTIAL INCIDENTAL OR PUNITIVE DAMAGES HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY ARISING OUT OF THE USE OF OR INABILITY TO USE SOFTWARE EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES This software is not designed or intended for use in on line control of aircraft air traffic aircraft navigation or aircraft communications or in the design construction operation or maintenance of any nuclear facility Licensee represents and warrants that it will not use or redistribute the Software for such purposes JOGL For graphics rendering NetLogo uses JOGL a Java API for OpenGL For more information about JOGL see_http jogl dev java net The library is distributed under the BSD license Copyright c 2003 2006 Sun Microsystems Inc All Rights Reserved Redistribution and use in source and binary forms with or wit
54. This is the same as how most people use numbers in everyday contexts but different from some programming languages Some languages treat integers and floating point numbers as distinct types Integers are always printed by NetLogo without the trailing 0 show 1 5 1 5 observer 3 If a number with a fractional part is supplied in a context where an integer is expected the fractional part is simply discarded So for example crt 3 5 creates three turtles the extra 0 5 is ignored The range of integers is 9007199254740992 2153 about 9 quadrillion Calculations that exceed this range will not cause runtime errors but precision will be lost when the least significant Programming Guide 105 NetLogo 4 0 User Manual binary digits are rounded off in order fit the number into 64 bits With very large numbers this rounding can result in imprecise answers which may be surprising show 2 60 1 2 60 gt true Calculations with smaller numbers can also produce surprising results if they involve fractional quantities since not all fractions can be precisely represented and roundoff may occur For example show L e e Me JUAS SEA DO AA gt 0 9999999999999999 show df DA Tf Oe fo O MAA of SA A Qe of DA A ALAS gt 1 0000000000000002 Any operation which produces the special quantities infinity or not a number will cause a runtime error Scientific notation Very large or very small floating point
55. Tutorial Let s write an extension that provides a single reporter called first n integers first n integers will take a single numeric input n and report a list of the integers O through n 1 Of course you could easily do this just in NetLogo it s only an example 1 Create extension folder Since an extension is a folder with several items we first need to create our folder In this example it is called example We will be doing all of our work in that folder We will also want to create a src sub folder to hold our Java code and a classes sub folder for the compiled classes 2 Write primitives The primitives are implemented as one or more Java classes The java files for these classes should be put in the src sub folder A command performs an action a reporter reports a value To create a new command or reporter create a class that implements the interface org nlogo api Command or org nlogo api Reporter which extend org nlogo api Primitive In most cases you can extend the abstract class org nlogo api DefaultReporter or org nlogo api DefaultCommand DefaultReporter requires that we implement Object report Argument args Context context throws ExtensionException Since our reporter takes an argument we also implement Syntax getSyntax Here s the implementation of our reporter in a file called src IntegerList java import org nlogo api public class IntegerList extends Defau
56. agent is the focus you can use the subject reporter Code Example Perspective Example Programming Guide 119 NetLogo 4 0 User Manual Drawing The drawing is a layer where turtles can make visible marks In the view the drawing appears on top of the patches but underneath the turtles Initially the drawing is empty and transparent You can see the drawing but the turtles and patches can t They can t sense the drawing or react to it The drawing is just for people to look at Turtles can draw and erase lines in the drawing using the pen down and pen erase commands When a turtle s pen is down or erasing the turtle draws or erases a line behind it whenever it moves The lines are the same color as the turtle To stop drawing or erasing use pen up Lines drawn by turtles are normally one pixel thick If you want a different thickness set the pen size turtle variable to a different number before drawing or erasing In new turtles the variable is set to 1 Lines made when a turtle moves in a way that doesn t fix a direction such as with set xy or move to the shortest path line that obeys the topology will be drawn Here s some turtles which have made a drawing over a grid of randomly shaded patches Notice how the turtles cover the lines and the lines cover the patch colors The pen size used here was 2 The stamp command lets a turtle leave an image of itself behind in the drawing and stamp erase lets it remove
57. all act as infix operators going between the two inputs as in standard mathematical use NetLogo correctly supports order of operations for infix operators The operators work as follows is addition is multiplication is subtraction is division is exponentiation lt is less than gt is greater than is equal to is not equal to lt is less than or equal gt is greater than or equal Note that the subtraction operator always takes two inputs unless you put parentheses around it in which case it can take one input For example to take the negative of x write x with the parentheses All of the comparison operators also work on strings All of the comparison operators work on agents Turtles are compared by who number Patches are compared top to bottom left to right so patch 0 10 is less than patch 0 9 and patch 9 0 is less than patch 10 0 Links are ordered by end points and in case of a tie by breed So link 0 9 is before link 1 10 as the end1 is smaller and link O 8 is less than link O 9 If there are multiple breeds of links unbreeded links will come before breeded links of the same end points and breeded links will be sorted in the order they are declared in the Procedures tab Agentsets can be tested for equality or inequality Two agentsets are equal if they are the same type turtle or patch and contain the same agents If you are not sure how NetLogo will interpret your code you should
58. anywhere in the code you are checking the bounds of the world or if some patches are not considered neighbors of the patches on the other side of the view it is likely that you are not using a torus If you check bounds in both the x and y directions it s a box in the x direction only a horizontal cylinder the y a vertical cylinder If you use no wrap primitives you are probably not modeling a torus however be careful with this criterion if you use a mix of no wrap and wrap primitives It may be that you were using a no wrap primitive for a visual element but the rest of the NetLogo world is still a torus After you ve determined the topology and changed it by editing the view you may have to make a few small changes to the code If you ve decided that the world is a torus you probably don t have to make any changes at all If your model only uses patch neighbors and diffuse you probably will not need to make many changes If your model has turtles that move around your next step is to determine what happens to them when they reach the edge of the world There are a few common options the turtle is reflected back into the world either systematically or randomly the turtle exits the system dies or the turtle is hidden It is no longer necessary to check the bounds using turtle coordinates instead we can just ask NetLogo if a turtle is at the edge of the world There are a couple ways of doing this the simplest is to use the can move primi
59. are also listed under Sample Models others are unique to this section See the info tabs of the models for more information on the curricula they go with Code Examples These are simple demonstrations of particular features of NetLogo They ll be useful to you later when you re extending existing models or building new ones For example if you wanted to put a histogram within your model you d look at Histogram Example to find out how HubNet Computer Activities This section contains participatory simulations for use in the classroom For more information about HubNet see the HubNet Guide What s Next If you want to learn how to explore models at a deeper level Tutorial 2 Commands will introduce you to the NetLogo modeling language In_Tutorial 3 Procedures you can learn how to alter and extend existing models and build your own models 36 Tutorial 1 Models Tutorial 2 Commands In Tutorial 1 you had the opportunity to view some of the NetLogo models and you have successfully navigated your way through opening and running models pressing buttons changing slider and switch values and gathering information from a model using plots and monitors In this section the focus will start to shift from observing models to manipulating models You will start to see the inner workings of the models and be able to change how they look Sample Model Traffic Basic e Go to the Models Library File menu e Open up Traf
60. as a list of three numbers programmable slider bounds you can now use any NetLogo reporter as the min max or increment of a slider exporting the world now includes all plot data and when you import a world the contents of plots are restored the sound extension can now play audio files in addition to MIDI sounds notes monitors and output areas now have editable font size the color of text in notes is now editable and a note s background may now optionally be transparent Snap to Grid in Interface tab added menu items and F1 keyboard shortcut for quickly accessing NetLogo Dictionary sliders may now be vertical or horizontal model files with unsaved changes are auto saved to a temporary files directory in case of freezes crashes What s New 4 4 NetLogo 4 0 User Manual HubNet clients are much easier to edit now the client is no longer a separate model Mathematica NetLogo link provides a real time link between Mathematica and NetLogo for controlling model runs and visualizing and analyzing results after the fact or in real time e language changes 4 4 o o o o gt What s New the ask command now always runs without interruption if you need the old style concurrent behavior use ask concurrent the syntax for using extensions is now simpler no underscores no double quotes no jar suffix new tick counter primitives tick ticks tick advance reset ticks changes to how number
61. as well Go commands These commands will be run over and over again to advance to the model to the next step Typically this will be the name of a procedure such as go but you may include any commands you like Stop condition This lets you do model runs of varying length ending each run when a certain condition becomes true For example suppose you wanted each run to last until there were no more turtles Then you would enter not any turtles If you want the length of runs to all be of a fixed length just leave this blank The run may also stop because the go commands use the stop command in the same way that stop can be used to stop a forever button The stop command may be used directly in the go commands or in a procedure called directly by the go commands The intent is that the same go procedure should work both in a button and in a BehaviorSpace experiment Note that the step in which stop is used is considered to have been aborted so no results will be recorded for that step Therefore the stopping test should be at the beginning of the go commands or procedure not at the end Final commands These are any extra commands that you want run once when the run ends Usually this is left blank but you might use it to call the export world command or record the results of the run in some other way Time limit This lets you set a fixed maximum length for each run If you don t want to set any maximum but want the length
62. ask turtle 0 create link to turtle 1 tie See also_untie tie mode tie mode This is a built in link variable It holds a string that is the name of the tie mode the link is currently in Using the tie and untie commands changes the mode of the link You can also set tie mode to NetLogo Dictionary 331 NetLogo 4 0 User Manual free to create a non rigid joint between two turtles see the_Tie section of the Programming Guide for details By default links are not tied See also tie untie timer timer Reports how many seconds have passed since the command reset timer was last run or since NetLogo started The potential resolution of the clock is milliseconds Whether you get resolution that high in practice may vary from system to system depending on the capabilities of the underlying Java Virtual Machine See also reset timer Note that the timer is different from the tick counter The timer measures elapsed real time in seconds the tick counter measures elapsed model time in ticks to to procedure name to procedure name input1 Used to begin a command procedure to setup clear all crt 500 end to circle radius crt 100 fd radius end to report to report procedure name to report procedure name input Used to begin a reporter procedure The body of the procedure should use report to report a value for the procedure See report to report average a b report a b 2
63. atlas ines Sede het Det a ale dates cated adie needle amp Dade see SAR Ad 238 Balches Ste eo TE D EE ASS eect e co cai aaa AM E Someta ones kek Sobek ai one cra fe 238 ET a E RR RR ds 238 O Nois SORA seeds A doe IN ASR oe 238 ASENNA CO ASEE E ac EEE RAS RESET A Sd da ata Sa 238 Gonstanis sara ARE o DO A Te A DO UI dos A Be Bats le to 238 Mathematical Constants errar tree a aerea narra aa inan 238 Boolean Constants nia A lado SENTES ee ANE 238 Golo CONSTANTS aii A dees even Gedichte Mie teeta ee 238 DS as ee BPD Se PO ns cd DR E ECE AR ERE A SE US O do PERE eee Re 239 OE S Op e o Se lO at 239 AG OS intima A a DO dae a a a bane daa weap EaD Sa 239 KEE acto xis A teeta don aa fe ween a a dq conta tee ute dt eo a qa 239 FOOT We aN Cra a O ae GE BPE A A AA ROT Rar PME Le RP O A A Rs ee Metter 239 EE A AL RARE DER E ia 240 APProximMaLe SD iscas isa tas soar wien a A ia da Aaah 240 APProximale 1D iii ani eae aa aa aaa Oda GRADE ae qa 240 Arithmetic Operators LN lt gt l lt gt 5 eterna 241 Daci 0 ti ARE E REDE ARE RR eS Ge et dl Se ea 243 ECO le Saa vate Saves D ea ano Lost da Dat aii E bak tb do ec eae ie tee ea OE os des sc eee Zu dSS 244 DOOD westside A AAA ARAS E a dl IS a 244 DOIN SOMOS tao ads SA Md a RN EEEE E O DRA a A E 244 O IARA AR RE RR PE RR OD RR RR RAR RR E ee eee eee ATT 244 DO ads cid asda E a pa Re E SOR DIDO e VD Ea E EN 245 but first bLbut lastibls ses a SO somas esa dete
64. breed name e has its breed built in variable set to that agentset Most often the agentset is used in conjunction with ask to give commands to only the turtles of a particular breed breed mice mouse breed frogs frog to setup clear all create mice 50 ask mice set color white create frogs 50 ask frogs set color green show breed of one of mice 7 prints mice show breed of one of frogs 7 prints frogs end show mouse 1 7 prints mouse 1 show frog 51 7 prints frog 51 show turtle 51 7 prints frog 51 NetLogo Dictionary 245 NetLogo 4 0 User Manual See also globals patches own turtles own lt breeds gt own create lt breeds gt lt breeds gt at lt breeds gt here but first bf but last bl but first list but first string but last list but last string When used on a list but first reports all of the list items of list except the first and but last reports all of the list items of list except the last On strings but first and but last report a shorter string omitting the first or last character of the original string 7 mylist is 2 4 6 5 8 12 set mylist but first mylist 7 mylist is now 4 6 5 8 12 set mylist but last mylist 5 mylist is now 4 6 5 8 show but first string 7 prints tring show but last string 7 prints strin C can move can move distance Reports true if the calling turtle can move distance in the direction it is facing without violat
65. by end2 any remaining ties are resolved by breed in the order they are declared in the procedures tab If you need descending order instead you can combine reverse with sort for example reverse sort turtles If you want your agents to be ordered by some other criterion than the standard ones sort uses you ll need to use sort by instead Here s an example sort by size of 21 lt size of 2 turtles This returns a list of turtles sorted in ascending order by their turtle variable size Asking a list of agents Once you have a list of agents you might want to ask them each to do something To do this use the foreach and ask commands in combination like this foreach sort turtles ask This will ask each turtle in ascending order by who number Substitute patches for turtles to ask 104 Programming Guide NetLogo 4 0 User Manual patches in left to right top to bottom order If you use foreach like this the agents in the list run the commands inside the ask sequentially not concurrently Each agent finishes the commands before the next agent begins them Note that you can t use ask directly on a list of turtles ask only works with agentsets and single agents Performance of lists If your model makes especially heavy use of lists especially long lists you may need to know the speed of the various NetLogo list operations to help you write code that runs fast NetLogo lists are singly lin
66. ccccccccceccceeeceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeneeeees 183 Installation ad rendas doi he tk dad E A na dnd ds A he A ARI A 184 KNOWN ISSUES a ee en E te ag a ite than soe 185 CROCS iia net Aas Pace ae end teat ncaa ate aod TE E ea eet ic a CDA AS se cae tee 185 EXTENSIONS Guide iii dad iii ai E EE EEE E EE E A E 187 USING EXI NAOS a E TOR da Sae lends 187 Where extensions are located reter narra nan cnn nan cn narra nan nana 187 Applets viaria A AA A a 188 Writing Extensions T E 188 SUMMA a 188 Example Sse AA Aa 188 TUI a E et Catia DS a a Eta Sd 189 Extension development tipS coccccccccncconcconnnonnnonnnonononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnnnss 192 vi NetLogo 4 0 User Manual Table of Contents Extensions Guide GONGCIUS I OM sec ARE PNAD SRT RR ON ibd E A RN DERA SN DS 193 Array and Table EXtenSlONS si cisececcsticccescsenctcuceceasenceeesSecusdunstvncediscndsecuessusdvssusugentvsacsstsessdedavessts 195 UN ie oe te he lait cae A leet RS Se ea sons dae DESSAS Sica Sekt 195 HOW O ISO iors het dhe A Adee an Sie oneal aid 195 Limitation on table keyS ccccccccccoccccnncnnncnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnnnss 195 Array Example ares dace Barra dash soe E E dude audade RO 195 Table example viva issverinssdiavaness chs ida 196 KNOWN ISSUES iii a as 196 Array primitives conri Ad Add 196 MAYO MAIS a aos 196 ACA A da 196 aray SO diu AAA tt bee ans 1
67. character string containing only the last character of the original string layout circle layout circle agentset radius layout circle list of turtles radius Arranges the given turtles in a circle centered on the patch at the center of the world with the given radius If the world has an even size the center of the circle is rounded down to the nearest patch The turtles point outwards If the first input is an agentset the turtles are arranged in random order If the first input is a list the turtles are arranged clockwise in the given order starting at the top of the circle Any non turtles in the list are ignored 7 in random order layout circle turtles 10 7 in order by who number layout circle sort turtles 10 7 in order by size layout circle sort by size of 1 lt size of 2 turtles 10 NetLogo Dictionary 281 NetLogo 4 0 User Manual __layout magspring __layout magspring turtle set link set spring constant spring length repulsion constant magnetic field strength magnetic field type bidirectional Very similar to layout spring but with an added layer of complexity The turtles in turtle set attract and repel each other depending on the links that are in link set between them but there is also a magnetic field which the links try to align with The link set is the set of links that exert forces on the turtles they are connected to Turtles that are connected to links in the link agentset but are not
68. clad guarantee due not only to the possibility of random hardware failure but also the possibility of human error in the design of your model NetLogo your Java VM your hardware and so on Will NetLogo and NetLogo 3D remain separate No The split is temporary Eventually a single unified version of NetLogo will support both 2D and 3D modeling We will be sure to design the 3D world support in such a way that it doesn t get in the way when you are building 2D models Models built in NetLogo 3D preview releases may require changes in order to run in the eventual unified version Downloading The download form doesn t work for me Can I have a direct link to the software Please write us at lbugs ccl northwestern edu and we ll either fix the problem with the form or provide you with an alternate method of downloading the software Downloading NetLogo takes too long Is it available any other way such as on a CD At present no If this is a problem for you contact us at feedback ccl northwestern edu downloaded and installed NetLogo but the Models Library has few or no models in it How can fix this So far users reporting this problem all used the without VM download option for Windows Uninstall NetLogo and try the with VM download instead Even if the with VM download fixes it for you please contact us at bugs Dccl northwestern edu so we can find out more details about your setup We d like to fix this in a fu
69. commercial use but there are some restrictions on redistribution and or modification unless you contact Uri Wilensky to arrange different terms We are in the process of reevaluating the language of the license in response to user feedback In the future we intend to send out a revised license Is the source code to NetLogo available At present no We are working on eventually releasing the source under an open source license In the meantime though NetLogo is not a closed platform We provide an API for controlling NetLogo from external Java code and an API for users to write new commands and reporters in Java See Controlling and Extensions in the User Manual We encourage users to write NetLogo extensions and share them with the NetLogo user community Do you offer any workshops or other training opportunities for NetLogo 218 FAQ Frequently Asked Questions NetLogo 4 0 User Manual We offer workshops from time to time If a workshop has been scheduled we will announce it on the NetLogo home page and on the netlogo users group If interested in this type of opportunity please contact us at feedback ccl northwestern edu Are there any NetLogo textbooks We at the CCL have hoped to write several NetLogo textbooks for quite some time These could be aimed at different audiences such as middle school high school undergraduate course in modeling or complexity practical guide for interested adults Unfortunately we
70. connections or WANs Calculator HubNet Calculator HubNet for Ti Navigator The Tl Navigator Classroom Learning System is a wireless classroom network for TI graphing calculators TI Navigator users can install a free NetLogo extension which integrates with Tl Navigator and allows the calculators to act as clients for participatory simulations like the ones that are available for Computer HubNet The Calculator HubNet extension is available from Inquire Learning LLC in collaboration with Texas Instruments Inquire Learning also offers support curricular materials and professional development for the Calculator HubNet system For more information on the Tl Navigator system itself please visit the Texas Instruments website at http education ti com navigator For more information on the Calculator HubNet extension for Tl Navigator please contact Inquire Learning at_calc hubnet inquirelearning com or visit http www inquirelearning com calc hubnet html Teacher workshops For information on upcoming workshops and NetLogo and HubNet use in the classroom please contact us at feedback ccl northwestern edu HubNet Authoring Guide To learn about authoring or modifying HubNet activities see the HubNet Authoring Guide Getting help If you have any questions about Computer HubNet or Calculator HubNet or need help getting started please email us at_feedback ccl northwestern edu HubNet Guide 167 NetLogo 4 0 User Manual
71. e g list 1 2 3 since the 1ist primitive only takes two inputs by default Parentheses are also used to override the default operator precedence e g 1 2 3 asin other programming languages Sometimes an input to a primitive is a command block zero or more commands inside square brackets or a reporter block a single reporter expression inside square brackets User defined procedures may not take a command or reporter block as input Operator precedences are as follows high to low e with at points in radius in cone e all other primitives and user defined procedures e A ex mod e e lt gt lt gt ls e and or xor Programming Guide 131 NetLogo 4 0 User Manual Compared to other Logos There is no agreed upon standard definition of Logo it is a loose family of languages We believe that NetLogo has enough in common with other Logos to earn the Logo name Still NetLogo differs in some respects from most other Logos The most important differences are as follows Surface differences e The precedence of mathematical operators is different Infix math operators like etc have lower precedence than reporters with names For example in many Logos if you write sin x 1 it willbe interpreted as sin x 1 NetLogo on the other hand interprets it the way most other programming languages would and the way the same expression would be interpreted in standard mathematical notation
72. e reload extensions forces NetLogo to reload all extensions the next time you compile your model Without this command changes in your extension JAR will not take effect until you open a model or restart NetLogo Third party JARs If your extension depends on code stored in a separate JAR copy the extra JARs into the extension Whenever an extension is imported NetLogo makes all the JARs in its folder available to the extension If you plan to distribute your extension to other NetLogo users make sure to provide installation instructions 192 Extensions Guide NetLogo 4 0 User Manual Supporting old Java versions NetLogo works with Java versions 1 4 1 and later If you want your extension to be usable by all NetLogo users your extension should support Java 1 4 1 The easiest way is to accomplish this is do all your development with the 1 4 1 JDK It s also possible to develop for Java 1 4 using the Java 1 5 or 1 6 compiler but you need to do two things e Use the target 1 4 option to javac or equivalent in your IDE to tell the newer compiler to emit class files that are compatible with the older Java versions This ensures that your code doesn t use any 1 5 only or 1 6 only Java language features e Use the bootclasspath option to javac or IDE equivalent to compile against the 1 4 Java class libraries Note that this requires installing the JDK 1 4 anyway This ensures that your code doesn t make any 1 5 only or 1 6 onl
73. end to report absolute value number ifelse number gt 0 report number report number end 332 NetLogo Dictionary NetLogo 4 0 User Manual to report first turtle report who 0 reports true or false end towards towards agent Reports the heading from this agent to the given agent If wrapping is allowed by the topology and the wrapped distance around the edges of the world is shorter towards will use the wrapped path Note asking for the heading from an agent to itself or an agent on the same location will cause a runtime error set heading towards turtle 1 7 Same as face turtle 1 See also_face towardsxy towardsxy x y Reports the heading from the turtle or patch towards the point x y If wrapping is allowed by the topology and the wrapped distance around the edges of the world is shorter towardsxy will use the wrapped path Note asking for the heading to the point the agent is already standing on will cause a runtime error See also_facexy turtle turtle number lt breed gt number Reports the turtle with the given who number or_nobody if there is no such turtle For breeded turtles you may also use the single breed form to refer to them ask turtle 5 set color red 7 turtle with who number 5 turns red NetLogo Dictionary 333 NetLogo 4 0 User Manual turtle set turtle set valuel turtle set value value2 Reports an agentset containing all
74. exhibit BehaviorSpace can be a powerful assistant to the modeler BehaviorSpace Guide 153 NetLogo 4 0 User Manual Historical Note Old versions of NetLogo prior to 2 0 included an earlier version of the BehaviorSpace tool That version was much different It wasn t nearly as flexible in the kinds of experiments it let you set up But it had facilities for display and analyzing experiment results that are missing from the current version With the current version it is assumed that you will use other software to analyze your results We hope to re add data display and analysis facilities to a future version of BehaviorSpace How It Works To begin using BehaviorSpace open your model then choose the BehaviorSpace item on NetLogo s Tools menu Managing experiment setups The dialog that opens lets you create edit duplicate delete and run experiment setups Experiments are listed by name and how by model runs the experiment will consist of Experiment setups are considered part of a NetLogo model and are saved as part of the model To create a new experiment setup press the New button Creating an experiment setup In the new dialog that appears you can specify the following information Note that you don t always need to specify everything some parts can be left blank or left with their default values depending on your needs Experiment name If you have multiple experiments giving them different names will help you
75. fewer or more than two inputs but in order to do so you must enclose the entire call in parentheses e g list random 10 list random 10 random 20 random 30 For more information see_Varying number of inputs Some kinds of lists are most easily built using the n values reporter which allows you to construct a list of a specific length by repeatedly running a given reporter You can make a list of the same value repeated or all the numbers in a range or a lot of random numbers or many other possibilities See dictionary entry for details and examples The_of primitive lets you construct a list from an agentset It reports a list containing each agent s value for the given reporter The reporter could be a simple variable name or a more complex expression even a call to a procedure defined using to report A common idiom is Programming Guide 101 NetLogo 4 0 User Manual max of turtles sum of turtles and so on You can combine two or more lists using the_sentence reporter which concatenates lists by combining their contents into a single larger list Like 1ist sentence normally takes two inputs but can accept any number of inputs if the call is surrounded by parentheses Changing list items Technically lists can t be modified but you can construct new lists based on old lists If you want the new list to replace the old list use set For example set mylist 2 7 5 Bob 3 0 2 mylist is now
76. gt Import HubNet Client Then when asked import from the Interface Tab You will no longer need the external client model and you will no longer need to point to it when setting the client interface so this hubnet set client interface COMPUTER my client nlogo becomes hubnet set client interface COMPUTER Performance of Lists The internal implementation of lists has changed which changes some of the performance properties of lists see the Programming guide for details on the current implementation Note that fput is much faster than 1put thus you may improve performance simply by switching to fput If performance is still a problem you may want to consider using the Array amp Table extensions Since NetLogo 3 0 Agentsets If your model is behaving strangely or incorrectly perhaps it s because since NetLogo 3 1 agentsets are now always in random order In prior versions of NetLogo agentsets were always ina fixed order If your code depended on that fixed order then it won t work anymore How to fix your model to work with randomized agentsets depends on the details of what your code is doing In some situations it is helpful to use the sort or sort by primitives to convert an agentset random order into a list of agents fixed order See Lists of agents in the Lists section of the Programming Guide Wrapping If you are seeing pieces of turtle shapes wrapping around the view edges it s because Net
77. have not yet been able to find the time to make these happen If anyone from the user community would like to collaborate on such a venture please let us know We would welcome it Is NetLogo available in a Spanish version German version your language here version etc At present NetLogo is available only in English We plan to eventually make it possible for users to produce their own foreign language packs for NetLogo and share them with each other In order to do this we need to separate all of the English text from the rest of the source code so that is separately editable We re not sure when this will happen Is NetLogo compiled or interpreted Short answer partially compiled we are working towards a full compiler Long answer NetLogo does include a compiler that generates Java byte code However this compiler does not yet support the entire language so some parts of user code are interpreted We are working on expanding the compiler to support the entire language Note that our compiler generates Java byte code and Java virtual machines have just in time compilers that in turn compile Java byte code all the way to native code so user code is ultimately translated to native code Has anyone built a model of lt x gt The best place to ask this question is on the NetLogo Users Group You should also check the Community Models section of our Models Library web page Are NetLogo models runs scientifically reprodu
78. is currently set to Let s investigate Wolf Sheep Predation s sliders e Read the contents of the Information tab located above the toolbar to learn what each of this models sliders represents The Information tab offers guidance and insight into the model Within this tab you will find an explanation of the model suggestions on things to try and other information You may want to read the Information tab before running a model or you might want to just start experimenting then look at the Information tab later What would happen to the sheep population if there was more initial sheep and less initial wolves at the beginning of the simulation 30 Tutorial 1 Models NetLogo 4 0 User Manual e Turn the grass switch off e Set the initial number sheep slider to 100 e Set the initial number wolves slider to 20 e Press setup and then go e Let the model run for about 100 time ticks Try running the model several times with these settings What happened to the sheep population Did this outcome surprise you What other sliders or switches can be adjusted to help out the sheep population e Set initial number sheep to 80 and initial number wolves to 50 This is close to how they were when you first opened the model e Set sheep reproduce to 10 0 e Press setup and then go e Let the model run for about 100 time ticks What happened to the wolves in this run When you open a m
79. is running the ask command itself in turn causing the turiles to run commands e setxy random xcor random ycor is a command using reporters A reporter as opposed to a command reports a result First each turtle runs the reporter random xcor which will report a random number from the allowable range of turtle coordinates along the X axis Then each turtle runs the reporter random y cor same for the Y axis Finally each turtle runs the set xy command with those two numbers as inputs That makes the turtle move to the point with those coordinates e end completes the definition of the setup procedure When you re done typing switch to the Interface tab and press the setup button you made before You will see the turtles scattered around the world Press setup a couple more times and see how the arrangement of turtles is different each time Note that some turtles may be right on top of each other Think a bit about what you needed to do to make this happen You needed to make a button in the interface and make a procedure that the button uses The button only worked once you completed both of these separate steps In the remainder of this tutorial you will often have to complete two or more similar steps to add another feature to the model If something doesn t appear to work after Tutorial 3 Procedures 49 NetLogo 4 0 User Manual you completed what you thought is the final step for that new feature continue to read ahead to se
80. layout radial turtle set link set root agent Arranges the turtles in turile set connected by links in link set in a radial tree layout centered around the root agent which is moved to the center of the world view Only links in the link set will be used to determine the layout If links connect turtles that are not in turtle set those turtles will remain stationary Even if the network does contain cycles and is not a true tree structure this layout will still work although the results will not always be pretty to make a tree set default shap crt 6 ask turtle 0 create link with turtle 1 create link with turtle create link with turtle 3 turtles circle N ask turtle 1 create link with turtle 4 create link with turtle 5 do a radial tree layout centered on turtle 0 layout radial turtles turtle 0 links end layout spring layout spring turtle set link set spring constant spring length repulsion constant Arranges the turtles in turtle set as if the links in link set are springs and the turtles are repelling each other Turtles that are connected by links in link set but not included in turtle set are treated as anchors and are not moved spring constantis a measure of the tautness of the spring It is the resistance to change in their length spring constant is the force the spring would exert if it s length were changed by 1 unit NetLogo Dictionary 283 NetLogo 4 0 User Manual spring lengt
81. like a bar chart or point like line except the points are not connected e Interval is the amount by which x advances every time you use plot y e If the Show in Legend checkbox is checked the selected pen will be a part of the legend in the upper right hand corner of the plot which can be revealed by clicking on the word Pens on the plot itself For more detailed information on how each of these features works you can see the Plotting Section of the Programming Guide 80 Interface Guide NetLogo 4 0 User Manual Sliders Sliders define global variables they are provided as an easy way to change the value of these global variables without changing the underlying code When you place a slider in the Interface tab the edit dialog automatically opens as with all widgets Most of the fields will be familiar However it is important to notice the the minimum maximum and increment fields will take any reporter expression not just constants So for example you could make the minimum min pxcor and the maximum max pxcor and the slider bounds will automatically adjust when you change the size of the world OOO Slider Global variable Minimum Increment Maximum min pxcor 1 max pxcor Value SO Units optional C vertical Cancel 50 Information Tab The Information tab provides an introduction to the model and an explanation of how to use it things to explore possible extensions and NetLogo features It is very helpful when
82. messages when the users login and logout any time the user manipulates one of the interface elements that is pushes a button moves a slider clicks in the view etc We step through each message and decide what action to take depending on the type of message enter exit or other the hubnet message tag the name of the interface element and the hubnet message source of the message the name of the client the message came from 170 HubNet Authoring Guide NetLogo 4 0 User Manual On an enter message we create a turtle with a user id that matches the hubnet message source which is the name that each user enters upon entering the activity it is guaranteed to be unique to create new student create students 1 set user id hubnet message sourc set label user id set step size 1 send info to clients end At this point we set any other client variables to default values and send them to the clients if appropriate We declared a student s own variable for every interface element on the client that holds state that is anything that would be a global variable on the server sliders choosers switches and input boxes It is important to make sure that these variables stay synchronized with the values visible on the client When the clients logout they send an exit message to the server which gives you a chance to clean up any information you have been storing about the client in this case we merely have to ask the
83. namely as sin x 1 e The and and or reporters are special forms not ordinary functions and they short circuit that is they only evaluate their second input if necessary e Procedures can only be defined in the Procedures tab not interactively in the Command Center e Reporter procedures that is procedures that report return a value must be defined with to report instead of to The command to report a value from a reporter procedure is report not output e When defining a procedure the inputs to the procedure must be enclosed in square brackets e g to square x e Variable names are always used without any punctuation always foo never foo or foo To make this work instead of a make command taking a quoted argument we supply a set special form which does not evaluate its first input As a result procedures and variables occupy a single shared namespace The last three differences are illustrated in the following procedure definitions most Logos NetLogo to square x to report square x output x x report x x end end Deeper differences e NetLogo is lexically scoped not dynamically scoped e NetLogo has no word data type what Lisp calls symbols Eventually we may add one but since it is seldom requested it may be that the need doesn t arise much in agent based modeling We do have strings In most situations where traditional Logo would use words we simply use strings instead For example in
84. no neighboring patch has a smaller value than the current patch the turtle stays put If there are multiple patches with the same lowest value the turtle picks one randomly Non numeric values are ignored downhill considers the eight neighboring patches downhill4 only considers the four neighbors Equivalent to the following code assumes variable values are numeric move to patch here go to patch center let p min one of neighbors patch variable 7 or neighbors4 if patch variable of p lt patch variable face p move to p Note that the turtle always ends up on a patch center and has a heading that is a multiple of 45 downhill or 90 downhill4 See also_uphill uphill4 dx dy dx dy Reports the x increment or y increment the amount by which the turtle s xcor or ycor would change if the turtle were to take one step forward in its current heading 256 NetLogo Dictionary NetLogo 4 0 User Manual Note dx is simply the sine of the turtle s heading and dy is simply the cosine If this is the reverse of what you expected it s because in NetLogo a heading of 0 is north and 90 is east which is the reverse of how angles are usually defined in geometry Note In earlier versions of NetLogo these primitives were used in many situations where the new patch ahead primitive is now more appropriate E empty empty list empty string Reports true if the given list or string is empty false otherwise
85. no new pen is created and the existing pen is set to the the current pen If a permanent pen with that name already exists in the current plot you get a runtime error The new temporary plot pen has the following initial settings e Pen down e Color black e Mode O line mode e Interval 1 252 NetLogo Dictionary NetLogo 4 0 User Manual See clear plot clear all plots and set current plot pen D date and time date and time Reports a string containing the current date and time The format is shown below All fields are fixed width so they are always at the same locations in the string The potential resolution of the clock is milliseconds Whether you get resolution that high in practice may vary from system to system depending on the capabilities of the underlying Java Virtual Machine show date and time gt 01 19 36 685 PM 19 Sep 2002 die die A The turtle dies if xcor gt 20 die all turtles with xcor greater than 20 die See also ct diffuse diffuse patch variable number Tells each patch to share number 100 percent of the value of patch variable with its eight neighboring patches number should be between 0 and 1 Regardless of topology the sum of patch variable will be conserved across the world If a patch has fewer than eight neighbors the remainder stays on the patch at the edge of the world Note that this is an observer command only even though you might expect itto be a
86. o AP a a AA de oe 146 KNOWN ISSUOS 32 22 E es ioe aoe sesso o 146 NetLogo 4 0 User Manual Table of Contents Shape Ds A ae eu PRES POET ace MAING A a O ANNE Creating and Editing Link Shapes acia dd Changing Link Shape Propeches nido oi USING Shapesan a Mode cais aaa dear A as Managing experiment SCtUDS oooooocococooonooononnncnnnnonnnnnnonnnnnnnnonnnn non nnnonnnnnnnnnnnnnnnnnnnonennnnos Creaiing an experiment SOU ic ci cd alis BELT e E E A A E E NEEE EE N E EEEE SRS OS E AR RD Understanding HubNet cocccccccncccniceninenineninenineninenenenenenennnnrrn rr rn Nello ie HubNet Architecture ccecceeceeecceeeceeecseeceseceeceecneeueeeeeeseeuneeeeeeneeeneesneesneeenensneenneenaes Computer HubNeL par idos ACUM A A A A e OS TrQUDIeShOOtINQ cccccccccncccnnccnncnoncnnncnnnnnnncnnnnnnnennnernnnrnnrrnnrrrn A E A Known e AAPP A A E E E Galculator HUBNT es nsn a sedan a T a Aa a aae aT Calculator HubNet for Tl Navigator ccococooccccccconccnnnnanonnnnnnnccnnnnnnnonnnnnncncnnnnnnnnnnnnnnnnnn ICATSON HubNet Authonng CUE COMMON rut nonin ES RR RE tandems o NetLogo 4 0 User Manual Table of Contents HubNet A th ring QUIE iiss ear aara parra aa AAA aaa Aaaa PA ae veacuceueencasves accsdecreceaeetoanaoevecekinctvacaten 169 General HubNet INfOrMAtiON cccconocccncnnnncnncnnnnccnnnnnnccnonanononononanonononanacano nana nano nanacanonnnananes 169 Godina H bNet Activities aint di 169 SO A E O OD O 1
87. of patches 7 turtle moves to the center of a random patch move to max one of turtles size 7 turtle moves to same point as biggest turtle Note that the turtle s heading is unaltered You may want to use the face command first to orient the turtle in the direction of motion See also_setxy movie cancel movie cancel Cancels the current movie movie close movie close Stops the recording of the current movie NetLogo Dictionary 293 NetLogo 4 0 User Manual movie grab view movie grab interface movie grab view movie grab interface Adds an image of the current view or the interface panel to the current movie 7 make a 20 step movie of the current view setup movie start out mov repeat 20 movie grab view go movie close movie set frame rate movie set frame rate frame rate Sets the frame rate of the current movie The frame rate is measured in frames per second If you do not explicitly set the frame rate it defaults to 15 frames per second Must be called after movie start but before movie grab view or movie grab interface See also movie status movie start movie start filename Creates a new movie filename specifies a new QuickTime file where the movie will be saved so it should end with mov See also movie grab view movie grab interface movie cancel movie status movie set frame rate movie close movie status movie status Reports a string describing the current movie
88. of the runs to be controlled by the stop condition instead enter 0 156 BehaviorSpace Guide NetLogo 4 0 User Manual Running an experiment When you re done setting up your experiment press the OK button followed by the Run button You will be prompted to select the formats you would like the data from your experiment saved in Data is collected for each interval run or step according to the setting of Measure runs at every step option Table format lists each interval in a row with each metric in a separate column Table data is written to the output file as each run completes Table format is suitable for automated processing of the data such as importing into a database or a statistics package Spreadsheet format calculates the min mean max and final values for each metric and then lists each interval in a row with each metric in a separate column Spreadsheet data is more human readable than Table data especially if imported into a spreadsheet application Note however that spreadsheet data is not written to the results file until the experiment finishes Since spreadsheet data is stored in memory until the experiment is done very large experiments could run out of memory And if anything interrupts the experiment such as a runtime error running out of memory or a crash or power outage no results will be written For long experiments you may want to use both spreadsheet and table formats so that if something happens y
89. or the agent you are watching following or riding press the zoom button and drag up and down along the 3D View Note when you are in follow or ride mode zooming will switch you between ride and follow since ride is just a special case of follow where the distance at which you are following is 0 To change the position of the observer without changing the direction it is facing select the move button and drag the mouse up down left and right inside the 3D View while holding down the mouse button To allow the mouse position and state to be passed to the model select the interact button and it will function just as the mouse does in the 2D view To return the observer and focus point to their default positions press the Reset Perspective button or use the reset perspective command Fullscreen Mode To enter fullscreen mode press the Full Screen button to exit fullscreen mode press the Esc key Note Fullscreen mode doesn t work on some computers It depends on what kind of graphics card you have See the System Requirements for details 3D Shapes Some shapes have true 3D counterparts a 3D circle is actually a sphere in the 3D view so they are automatically mapped to that shape Shape name 3D shape default 3D turtle shape Interface Guide 77 NetLogo 4 0 User Manual circle sphere dot small sphere square cube triangle cone line half 3D line half car 3D car All other shapes are int
90. out lt breed gt to out link to out lt breed gt to turtle out link to turtle Reports the link from the caller to turtle If no link exists then it reports nobody ert 2 ask turtle 0 create link to turtle 1 show out link to turtle 1 shows link 0 1 ask turtle 1 show out link to turtle 0 shows nobody output print output show output type output write output print value output show value output type value output write value These commands are the same as the print show type and write commands except that value is printed in the model s output area instead of in the Command Center If the model does not have a separate output area then the Command Center is used P patch patch xcor ycor Given the x and y coordinates of a point reports the patch containing that point The coordinates are absolute coordinates they are not computed relative to the calling agent as with patch at If x and y are integers the point is the center of a patch If x or y is not an integer rounding to the nearest integer is used to determine which patch contains the point If wrapping is allowed by the topology the given coordinates will be wrapped to be within the world If wrapping is not allowed and the given coordinates are outside the world reports nobody ask patch 3 4 set pcolor green 7 patch with pxcor of 3 and pycor of 4 turns green NetLogo Dictionary 303 NetLogo 4 0 User Manual
91. party and noticed how people cluster in groups You may have also noticed that people do not stay within one group but move throughout the party As individuals move around the party the groups change If you watched these changes over time you would notice patterns forming For example in social settings people tend to exhibit different behavior than when they are at work or home Individuals who are confident within their work environment may become shy and timid at a social gathering And others who are quiet and reserved at work may be the party starter with friends The patterns may also depend on what kind of gathering it is In some settings people are trained to organize themselves into mixed groups for example party games or school like activities But in a non structured atmosphere people tend to group in a more random manner Is there any type of pattern to this kind of grouping Let s take a closer look at this question by using the computer to model human behavior at a party NetLogo s Party model looks specifically at the question of grouping by gender at parties why do groups tend to form that are mostly men or mostly women Let s use NetLogo to explore this question What to do 1 Start NetLogo 2 Choose Models Library from the File menu NetLogo HEM Edit Tools Zoon 8 4 New N tl 3 Open O Models Library 3M t mi tet e B Deleg Save 36S Save AS Save As Applet Print dE P
92. places but it was difficult for users to know whether that command was needed and if so where In NetLogo 4 0 without interruption is no longer necessary unless your model uses ask concurrent or a turtle or patch forever button containing code that depends on simulated concurrency In most models all uses of without interruption can be removed The simulated concurrency formerly employed by ask is still accessible in three ways e You may use the ask concurrent primitive instead of ask to get the old simulated concurrency e Commands issued in the Command Center directly to turtles patches or links have an implied ask concurrent e Turtle patch and link forever buttons have an implied ask concurrent as well Note that ask itself is always serial regardless of the context in which it is used however In our own Models Library models that make use of this concurrency are rare A prominent example though is Termites which uses a concurrent turtle forever button Tick counter NetLogo now has a built in tick counter for representing the passage of simulated time You advance the counter by one using the tick command If you need to read its value there s a reporter called ticks The clear a11 command resets the tick counter so does reset ticks In most models the tick counter will be integer valued but if you want to use smaller increments of time you can use the tick advance command to advance the tick counter by any po
93. right why does my model seem to stop The only way NetLogo can make your model run faster is by updating the view less frequently As you move the speed slider to the right view updates become less and less frequent Since view updates take time that means more speed However fewer updates also means that the updates come farther apart When several seconds pass between updates it may seem like your model has stopped It hasn t It s running at full speed Watch the tick counter If your model uses it If it doesn t watch something else such as a plot To get a feel for what s going it may help to gradually move the slider to the right rather than moving it all the way to the right all at once If you find the updates too infrequent at the rightmost position don t push the slider that far How do change how many patches there are Press the Settings button in the toolbar on the Interface tab A dialog will appear in which you may change the dimensions of the world A quicker method is to use the three sets of black arrows in the upper left corner of the 2D view Can I use the mouse to paint in the view NetLogo does not have a built in set of painting tools for painting in the view But with only a few lines of code you can add painting capability to your model To see how it s done look at Mouse Example in the Code Examples section of the Models Library The same techniques can be used to let the user interact with yo
94. server and the model then determines how those messages affect the model All widgets on the client have a tag which is a name that uniquely identifies the widget When the server receives a message from that widget the tag is found in hubnet message tag For example if you have a button called move left a slider called step size a switch called all in one step and a monitor called Location the tags for these interface elements will be as follows interface element tag move left move left step size step size all in one step _ all in one step Location Location Note that you can only have one interface element with a specific name Having more than one interface element with the same tag in the client interface will result in unpredictable behavior since itis not clear which element you intended to send the information to View Updates on the Clients The simplest way to display the world in the view on the client is to use view mirroring When view mirroring is on enabled through the HubNet Control Center the client views are automatically updated to reflect the state of the world All the clients will have the same view which is the same as the view on the server The view updates are triggered about 5 times per second which means that there could be a lot of messages sent to the clients If you are having trouble with performance you may want to try using no display and display to reduce the number of u
95. support for multiple processors cores as follows e Allow multiple models to be open simultaneously each running in a different thread and hence on a different processor core e Modify BehaviorSpace to optionally do multiple model runs in parallel in a configurable number of separate threads so the runs would be spread across available processors cores Can distribute NetLogo model runs across a cluster of computers Many of the same comments in the previous answer apply It is not possible to split a single model run across multiple computers but you can have each machine in a cluster doing one or more 224 FAQ Frequently Asked Questions NetLogo 4 0 User Manual separate independent model runs using either BehaviorSpace or our Controlling API Numerous users are already using NetLogo on clusters You can seek them out on the NetLogo Users Group want to try HubNet Can I Yes There are two types of HubNet available With Computer HubNet participants run the HubNet Client application on computers connected by a regular computer network In Calculator HubNet created in conjunction with Texas Instruments participants use Texas Instruments graphing calculators and the Tl Navigator Classroom Learning System See the HubNet section of the user manual for more details on Calculator HubNet for Tl Navigator For more information on HubNet in general see the HubNet Guide Usage When move the speed slider all the way to the
96. th dE NUA RR O DAS 212 A oE A A Danada aa ca Del ten atenees 212 DFOMORTOS OPOR RIR RR CRER a O 212 PEO DONE ci desu dote da O tal eadebe ad 212 FAQ Frequently Asked QUESTIONS ccccececessseeeeeeeeeeeesnneeeeneeeeeeeeseseeeeneeeseseeesneeseeneeeeeeeeensnaees 215 QUESTIONS 2 carte eis teaches ea add case ACI Sado as nota seas aed oe ote eae 215 Genetal cs am a Slade ates eure Ghee SO totes hasta De a ct 215 Downloadina eee A A nana aaa anna a aaa nana nana E E 215 Jane oE CEE EE EE ias 215 RUANIN eiit a a a a a a A T E 216 USO tota aora RR RT 216 A E A 216 EIIE NOIRS PACO ias mma ic 217 EXTENSIONS tas ass aa sagas SAS detec owe SANS Sn ut doa A CO EVA aa Ud ani Dava To DDS ESA 217 AP ca toe dat Ra etek q Ta mn aa e SR ao da ie oe aa 217 Why is it called N tLogo ans vadera dois recs ada e NR Ran Ro Ea da 217 How do cite NetLogo in an academic publication ia 217 How do cite a model from the Models Library in a publication 2 217 Where and when was NetLogo Created c cssccccccccssssesseeeeeeeeeeeeseeseseeeeeeeeesssssnaeees 217 What programming language was NetLogo written in reenn 218 vili NetLogo 4 0 User Manual Table of Contents FAQ Frequently Asked Questions What s the difference between StarLogo MacStarLogo StarLogoT and NetLogo 218 What license is NetLogo released under Are there are any legal restrictions on use redistribution Edd ii a
97. the next agent starts One agent runs all of the commands then the next agent runs all of them and so on For example if you write ask turtles tds 1 set color red first one turtle moves and turns red then another turtle moves and turns red and so on But if you write it this way ask turtles fd 1 ask turtles set color red first all of the turtles move After they have all moved they all turn red Another form of the ask command with a different ordering rule is also available See Ask Concurrent below Agentsets An agentset is exactly what its name implies a set of agents An agentset can contain either turtles patches or links but not more than one type at once An agentset is not in any particular order In fact it s always in a random order And every time you use it the agentset is in a different random order This helps you keep your model from treating any particular turtles patches or links differently from any others unless you want them to be Since the order is random every time no one agent always gets to go first You ve seen the turtles primitive which reports the agentset of all turtles the patches primitive which reports the agentset of all patches and the 1 inks primitive which reports the agentset of all links But what s powerful about the agentset concept is that you can construct agentsets that contain only some turtles some patches or some links For example all the red turt
98. the bottom of the editing window The previews show your shape as it might appear in your model including how it looks as it rotates The number below each preview is the size of the preview in pixels When you edit the view patch size is also measured in pixels So for example the preview with 20 below it shows you how your shape would look on a turtle of size 1 on patches of size 20 pixels The rotatable feature can be turned off if you want a shape that always faces the same way regardless of the turtle s heading Overlapping Shapes New elements go on top of previous elements You can change the layering order by selecting an element and then using the Bring to front and Send to back buttons Undo At any point you can use the Undo button to undo the edit you just performed Colors Elements whose color matches the Color that changes selected from a drop down menu the default is gray will change color according to the value of each turtle s color variable in your model Elements of other colors don t change For example you could create cars that always have yellow headlights and black wheels but different body colors Other buttons The Rotate Left and Rotate Right buttons rotate elements by 90 degrees The Flip Horizontal and Flip Vertical buttons reflect elements across the axes These four buttons will rotate or flip the entire shape unless an element is selected in which case only that element is affec
99. the design construction operation or maintenance of any nuclear facility 6 Copyright Information NetLogo 4 0 User Manual Matrix3D For 3D matrix operations NetLogo uses the Matrix3D class It is distributed under the following license Copyright c 1994 1996 Sun Microsystems Inc All Rights Reserved Sun grants you Licensee a non exclusive royalty free license to use modify and redistribute this software in source and binary code form provided that i this copyright notice and license appear on all copies of the software and ii Licensee does not utilize the software in a manner which is disparaging to Sun This software is provided AS IS without a warranty of any kind ALL EXPRESS OR IMPLIED CONDITIONS REPRESENTATIONS AND WARRANTIES INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE OR NON INFRINGEMENT ARE HEREBY EXCLUDED SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING MODIFYING OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE PROFIT OR DATA OR FOR DIRECT INDIRECT SPECIAL CONSEQUENTIAL INCIDENTAL OR PUNITIVE DAMAGES HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY ARISING OUT OF THE USE OF OR INABILITY TO USE SOFTWARE EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES This software is not designed or intended for use in on line contro
100. the item currently being computed starting from zero show n values 5 1 gt 1 11 11 show n values 5 gt 0 1 2 3 4 show n values 3 turtle gt turtle 0 turtle 1 turtle 2 show n values 5 gt 0 1 4 9 16 See also_reduce filter neighbors neighbors4 neighbors neighbors4 a Pg Reports an agentset containing the 8 surrounding patches neighbors or 4 surrounding patches neighbors4 show sum count turtles here of neighbors 7 prints the total number of turtles on the eight 7 patches around the calling turtle or patch show count turtles on neighbors 7 a shorter way to say the same thing ask neighbors4 set pcolor red turns the four neighboring patches red lt breed gt neighbors link neighbors lt breed gt neighbors link neighbors Reports the agentset of all turtles found at the other end of undirected links connected to the calling turtle ert 3 NetLogo Dictionary 297 NetLogo 4 0 User Manual ask turtle 0 create links with other turtles ask link neighbors set color red turtles 1 and 2 turn red ask turtle 1 ask link neighbors set color blue turtle 0 turns blue end lt breed gt neighbor link neighbor lt breed gt neighbor turile link neighbor turtle Reports true if there is an undirected link between turtle and the caller Cre 2 ask turtle 0 create link with turtle 1 show link neighbor turtle 1 prints tr
101. the patch See also color pen down pd pen erase pe pen up pu 306 NetLogo Dictionary NetLogo 4 0 User Manual pen down pen erase pen up The turtle changes modes between drawing lines removing lines or neither The lines will always be displayed on top of the patches and below the turtles To change the color of the pen set the color of the turtle using set color Note When a turtle s pen is down all movement commands cause lines to be drawn including jump setxy and move to Note These commands are equivalent to setting the turtle variable pen mode to down up and erase Note On Windows drawing and erasing a line might not erase every pixel pen mode A This is a built in turtle variable It holds the state of the turtle s pen You set the variable to draw lines erase lines or stop either of these actions Possible values are up down and erase pen size A This is a built in turtle variable It holds the width of the line in pixels that the turtle will draw or erase when the pen is down or erasing plabel e A This is a built in patch variable It may hold a value of any type The patch appears in the view with the given value attached to it as text You can set this variable to add change or remove a patch s label All patch variables can be directly accessed by any turtle standing on the patch See also plabel color label label color plabel color NetL
102. the turtle to look in another direction besides straight ahead try patch left and ahead and patch right and ahead If you want the turtle to have a full cone of vision use the in cone primitive You can also find out the next patch a turtle would cross into if it moved forward continuously See Next Patch Example in the Code Examples section of the Models Library FAQ Frequently Asked Questions 231 NetLogo 4 0 User Manual Can agents sense what s in the drawing layer No If you want to make marks that agents can sense use patch colors I m getting numbers like 0 10000000004 and 0 799999999999 instead of 0 1 and 0 8 Why See the Math section of the Programming Guide in the User Manual for a discussion of this issue The documentation says that random float 1 might return O but will never return 1 What if want 1 to be included It really doesn t matter Even if 1 were a possible result it would only come up approximately 1 in 2164 tries which means you d be waiting hundreds of years before it ever came up exactly 1 Nonetheless if you are convinced that it really must be possible to get 1 you can use precision to round your answer to a certain number of decimal places For example print precision random float 1 10 0 2745173723 If you use this method note that O and 1 are only half as likely to come up as other answers To see why this is so consider the case where you only keep one digit after the decimal
103. to itself Also you cannot have more than one undirected link of the same breed between the same two nodes nor can you have more than one directed link of the same breed going in the same direction between two nodes If you try to create a link where one of the same breed already exists nothing happens If you try to create a link from a turtle to itself you get a runtime error to setup ert 5 7 turtle 1 creates links with all other turtles 7 the link between the turtle and itself is ignored ask turtle 0 create links with other turtles show count links shows 4 7 this does nothing since the link already exists ask turtle 0 create link with turtle 1 show count links shows 4 since the previous link already existed ask turtle 2 create link with turtle 1 show count links shows 5 end directed link breed red links red link undirected link breed blue links blue link to setup ert Create links in both directions between turtle 0 7 and all other turtles ask turtle 0 create red links to turtles ask turtle 0 create red links from turtles show count links shows 8 7 now create undirected links between turtle 0 and other turtles ask turtle 0 create blue links with turtles show count links shows 12 end create turtles crt create lt breeds gt NetLogo Dictionary 251 NetLogo 4 0 User Manual create turtles number create turtles number commands crea
104. to the values of local variables myself and so on The code must be compiled first which takes time however compiled bits of code are cached by NetLogo and thus using run on the same string over and over is much faster than running on 318 NetLogo Dictionary NetLogo 4 0 User Manual different bits of code See also_runresult Note that you can t use run to define or redefine procedures Note that running code through run or runresult may be many times slower than running the same code directly runresult runresult string This agent interprets the given string as a NetLogo reporter and runs it reporting the result obtained The code runs in the agent s current context which means it has access to the values of local variables myself and so on The code must be compiled first which takes time however compiled bits of code are cached by NetLogo and thus using runresult on the same string over and over is much faster than running on different bits of code See also_run Note that running code through run or runresult may be many times slower than running the same code directly S scale color scale color color number range range Reports a shade of color proportional to number If range1 is less than range2 then the larger the number the lighter the shade of color But if range2 is less than range7 the color scaling is inverted If number is less than range7 then the darkest shade of color is chosen If
105. turtles on turtles own untie uphill uphill4 Patch related clear patches cp diffuse diffuse4 distance distancexy import pcolors import pcolors rgb inspect is patch myself neighbors neighbors4 nobody no patches of other patch patch at patch ahead patch at heading and distance patch here patch left and ahead patch right and ahead patch set patches patches own random pxcor random pycor self sprout sprout lt breeds gt subject Agentset all any ask ask concurrent at points lt breeds gt at lt breeds gt here lt breeds gt on count in cone max one of min one of n of neighbors neighbors4 no patches no turtles of one of other patch set patches sort sort by turtle set turtles with with max with min turtles at turtles here turiles on Color approximate hsb approximate rgb base colors color extract hsb extract rgb hsb import pcolors import pcolors rgb pcolor rgb scale color shade of wrap color NetLogo Dictionary 235 NetLogo 4 0 User Manual Control flow and logic and ask ask concurrent carefully end error message foreach if ifelse ifelse value let loop map not or repeat report run runresult semicolon set stop startup to to report wait while with local randomness without interruption xor World clear all ca clear drawing cd clear patches cp clear turtles ct display import drawing import pcolors import pcolors rgb no display max pxcor max pycor min pxcor min pycor
106. used crt to contain extra commands to randomize the new turtles headings for example rt random 360 or set heading random 360 These commands are no longer necessary when used inside crt Adding strings and lists Prior to NetLogo 4 0 the addition operator could be used to concatenate strings and join lists In current NetLogo only works on numbers To concatenate strings use the word primitive to join lists together use the sentence primitive This language change was made to increase the speed of code that uses Old code Transition Guide 135 NetLogo 4 0 User Manual print There are count turtles turtles New code print word There are count turtles turtles Likewise if you need to concatenate lists use SENTENCE This change is not handled automatically when converting old models users will need to change their code by hand We know this change will be awkward for users who are used to the old syntax We have made this change for efficiency and consistency A operator that adds only numbers can be implemented much more efficiently than one that handles several different data types Because addition is sucha common operation NetLogo s overall speed is affected Links NetLogo 3 1 had supports for using links to connect turtles to make networks graphs and geometric figures The links were themselves turtles In NetLogo 4 0 instead of links being turtles links are now an independent fourt
107. was saved by Export World Import Patch Load an image into the patches see the import pcolors command Colors Import Patch Load an image into the patches using RGB colors see the Colors RGB import pcolors rab command Import Drawing Load an image into the drawing see the import drawing command Import HubNet Load the interface from another model into the HubNet Client Editor Client Interface Quit Exits NetLogo On Macs this item is on the NetLogo menu instead Edit Cut Cuts out or removes the selected text and temporarily saves it to the clipboard Copy Copies the selected text Paste Places the clipboard text where cursor is currently located peke Pellas selected text Undo Undo last text editing action you performed Redo Redo last undo action you performed Procedures tabs ith Shift Right semicolons are used in NetLogo code to indicate comments Snap To Grid When enabled new widgets stay on a 5 pixel grid so it is easier to line Note this feature is disabled when zoomed in or out ools Halt Stops all running code including buttons and the command center Warning since the code is interrupted in the middle of whatever it was doing you may get unexpected results if you try to continue running the model without first pressing setup to start the model run over Globals Monitor Displays the values of all global variables Turtle Monitor Displays the values of all
108. which is visible or not in the view control strip Turtle patch and link monitors are easily available through the View just control click Macintosh or right click other systems on the turtle or patch you want to inspect and choose inspect turtle or inspect patch from the popup menu You can also watch follow or ride a turtle by selecting the appropriate item in the turtle sub menu Turtle patch and link monitors can also be opened from the Tools menu or by using the inspect command Some NetLogo models let you interact with the turtles and patches with your mouse by clicking and dragging in the View 76 Interface Guide NetLogo 4 0 User Manual Manipulating the 3D View At the bottom of the window there are buttons to move the observer or change the perspective from which you are looking at the world Rotate Zoom Move Interact Reset Perspective Full Screen A blue cross appears at the current focus point as you are adjusting these settings The little blue triangle will always point up the positive y axis so you can orient yourself in case you get lost It s easy to do To look at the world from a different angle press the rotate button click and drag the mouse up down left or right The observer will continue to face the same point as before where the blue cross is but its position in the relation to the xy plane will change To move closer or farther away from the world
109. you re first exploring a model 8960 NetLogo Wolf Sheep Predation Interface Information Procedures 2 F Find Edit This model explores the stability of predator prey ecosystems Such a system is called unstable if it tends to result in extinction for one or more species involved In contrast a system is stable if it tends to maintain itself over time despite fluctuations in population sizes There are two main variations to this model In the first variation wolves and sheep wander randomly around the landscape while the wolves look for sheep to prey on Each step costs the wolves energy and they must eat sheep in order to replenish their energy when they run out of energy they die To allow the naniilatinn ta eantinia aarh uinlf ar chaan hee a fivad nrnhshilit af ranrnadiicina at aach tima Interface Guide 81 NetLogo 4 0 User Manual We recommend reading the Information tab before starting the model The Information tab explains what principle is being modeled and how the model was created This display of the Information tab is not editable To edit the content of the Info tab click the Edit button or double click on a word which will also scroll you to the location you clicked on and highlight the word 000 NetLogo Wolf Sheep Predation Interface Information Procedures 2 Find WHAT IS IT This model explores the stability of predator prey ecosystems Such a system is ca
110. your model run faster It consists of a set of primitives for measuring how many times the procedures in your model are called during a run and how long each call takes Caveats Note on compatibility The extension requires that you use Java 1 5 or greater when running NetLogo as it uses features not present in Java 1 4 On Windows you should be fine since the NetLogo download includes Java 1 5 Mac users must have Mac OS X 10 4 or later since Apple does not offer Java 1 5 on 10 2 or 10 3 Caution The Profiler Extension is new and experimental It is not yet well tested or user friendly Nonetheless we think some users will find it useful Usage The profiler extension comes preinstalled To use the extension in your model add a line to the top of your procedures tab extensions profiler If your model already uses other extensions then it already has an extensions line in it so just add profiler to the list For more information on using NetLogo extensions see the Extensions Guide For examples that use the profiler extension see the Profiler Example model under Code Examples in the NetLogo Models Library Primitives profiler report profiler calls profiler calls procedure name Reports the number of times that procedure name was called If procedure name is not defined then reports 0 profiler exclusive time Profiler Extension 211 NetLogo 4 0 User Manual profiler exclusive time procedure name Report
111. 0000000000000004 show cos 90 gt 6 123233995736766E 17 This is an inherent issue with floating point arithmetic it occurs in all programming languages that use floating point numbers If you are dealing with fixed precision quantities for example dollars and cents a common technique is to use only integers cents internally then divide by 100 to get a result in dollars for display If you must use floating point numbers then in some situations you may need to replace a straightforward equality test suchas if x 1 with a test that tolerates slight imprecision for example if abs x 1 lt 0 0001 Also the precision primitive is handy for rounding off numbers for display purposes NetLogo monitors round the numbers they display to a configurable number of decimal places too Random Numbers The random numbers used by NetLogo are what is called pseudo random This is typical in computer programming That means they appear random but are in fact generated by a deterministic process Deterministic means that you get the same results every time if you start with the same random seed We ll explain in a minute what we mean by seed In the context of scientific modeling pseudo random numbers are actually desirable That s because it s important that a scientific experiment be reproducible so anyone can try it themselves and get the same result that you got Since NetLogo uses pseudo random numbers
112. 1 NUBNEt Tetch MOSSAGE a da an 271 hUBNCIEMESSADE A Aia 272 hubnet MEesSage SQUICB coocoocccococono nono nono nono nnnnnnnnnnnn nono nnnnnnnnnnn nono nn no nnnnnnnnnnnnnnnnnnnnnnnnnnns 272 hUDNet MEsSSsaQge taQ ccccccocccconooono ee 272 MUBNEt MOSSAGS WAITING Riiie ia 272 US tcs Dat 272 hubnei sefid risada a 273 NUDNEIT SENG VICW cc cccceccceeeceeeeceeseceeeeeeeeeceeecueeesaueuseueescueeeneueescueeeseceuseueeeceeeeseueasenees 273 hubnet Set cli nt interiace 0 ccccecccceececsccceveececcececsecsecuecesussceusesntecescecceeeecectuaesvaeess 273 E PR UR EGO UA ESR ERR NR RSA a i PEE NI SRE UN PRR FS PES ns OPE E O POR ee ae SP 274 Neate Sa CO hu De Te io ac id Da N ne Pel ee Moto cle oie cotista TN 274 CISC Ns cmo ca E A sda e tees his OR de ans ae ey 274 NetLogo 4 0 User Manual Table of Contents NetLogo Dictionary MESA RR RR RD TY er RENO VD 275 IM DOM GrAWING ss seer eee vtea A ead RES a dia 215 aa ole ate 010 01E REEE ee 275 import pcolors r0D una cidcid cies 276 IMPOM WOMG atasca iii an 276 A A Or iO qa e aa A DEN EA A eo OS 211 in lt breed gt neighbor in limk Neighbor ccccccconnnononccncnnonccononannonnncnccnnnnnannnncnnnnninns 277 in lt breed gt neighbors in lidk NeighboOES oooococconcoonoconocononononononnnnonnnonnnnnnnnnnnnnnnnnnnnnnos 211 in lt breed gt from in link from ccc cee ecececeeeceseeeueueeeseeeuesesensuaeeeeneuaueeeeeneeeesanes 278 INGA SS i
113. 168 HubNet Guide HubNet Authoring Guide This guide presents information you will need to understand and modify the code of existing HubNet Activities as well as write your own HubNet activities This guide assumes you are familiar with running HubNet activities basic NetLogo code and NetLogo interface elements for more general information about HubNet see the_HubNet Guide e General HubNet Information e Coding HubNet Activities Setup Receiving information from clients Sending information to clients e Calculator HubNet Information e Computer HubNet Information How To Make a Client Interface View Updates on the Clients 4 Clicking in the View on Clients Plot Updates on the Clients General HubNet Information The information presented in this section is specifically targeted at those using computer clients however much of the code presented can be reused with small modifications to use calculator clients Coding HubNet Activities Many HubNet Activities will share bits of the same code That is the code that it used to setup the network and the code that is used to receive information from and send information to the clients If you understand this code you should be able to easily make modifications to existing activities and you should have a good start on writing your own activities To get you started we have provided a Template model in HubNet Computer Activities gt Code Examples that contains the most basic component
114. 5 128 Programming Guide NetLogo 4 0 User Manual With ask the first turtle takes ten steps forward then the second turtle takes ten steps forward and so on With ask concurrent all of the turtles take one step forward Then they all take a second step and so on Thus the latter command is equivalent to repeat 5 ask turtles fd 1 Code Example Ask Concurrent Example shows the difference between ask and ask concurrent The behavior of ask concurrent cannot always be so simply reproduced using ask as in this example Consider this command ask concurrent turtles fd random 10 In order to get the same behavior using ask we would have to write turtles own steps ask turtles set steps random 10 while any turtles with steps gt 0 ask turtles with steps gt 0 fd 1 set steps steps 1 To prolong an agent s turn use the without interrupt ion command The command blocks inside some commands such as create turtles and hatch have an implied without interruption around them Note that the behavior of ask concurrent is completely deterministic Given the same code and the same initial conditions the same thing will always happen if you are using the same version of NetLogo and begin your model run with the same random seed In general we suggest you write your model so that it does not depend on the exact details of how ask concurrent works We make no guarantees that its semanti
115. 69 Receiving messages from ClientS cooooooococcncccnononoconncnnononnnnnononnnnnnnncnnnnnn non nnnnncnnnnnnnnos 170 Sending MESSAGES to cli ita 172 ExampleSia aaron dao aa 172 Calculator HubNet INfOrMatiQN ccooocccncnninccncnnonccnnnnnononononononononanonononanaccnnnnnncanonnnncannnnanannns 173 Computer HubNet IOMA ende 173 How To Make a Client INterface ooocccccnnnnccnnnnncccnnnnnaconononanonononanananonanananonanananonanananes 173 View Updates on the ClieNtS ooooooocccnnnncnnnoconccccononccnnonnanononnnnnonnnnnnnonnnnnncnnnnnnnnnnnnnnnnnnnn 173 Clicking in the View on ClienNtS ooococonccconcooooccccnnnncocnnnnonnnonnnncncnnnnnnnnnnnnnnncnnnanrnnnenennnnnns 174 Plot Updates on he Cl nado aos 174 A E OO ARO 2 AR uarscentecrsnerssater 175 SHLAA AMA A A O E wala E 175 Mac OS X or WiNdOWS Se 175 Linux and others a A A ea Eaa a rE ea 175 UsIN GOA dad a AS e aee irate 175 Where logs are StOred oococccncicoccconicononenenenenenenenenenenenenenennnnrnn rr rn rre 175 How to configure the logging OU unidad aereas 177 Advanced COMMUTATION si 178 TATE OT BNC Guides iii E A 179 Note on A 179 Example Wilco nearest ja 179 Example headless iza crias tig rren s eE ee e e eaa Aeee geadas age amada 180 BENAVIOLS PAGE nara tia teas tals asics a Ed E PO DE TAT 181 Other ODUONS id 182 GONnGCIUSION 23 AAA Ai 182 Mathematica A O 183 Mihatis A RT 183 What Cara CAO Wit ite aii da ae bd 183 Using the NetLogo Mathematica Link
116. 80 to 180 but is never exactly 180 Note that simply subtracting the two headings using the minus operator wouldn t work Just subtracting corresponds to always rotating clockwise from heading2 to heading1 but sometimes the counterclockwise rotation is shorter For example the difference between 5 degrees and 355 degrees is 10 degrees not 350 degrees show subtract headings 80 60 gt 20 show subtract headings 60 80 gt 20 show subtract headings 5 355 NetLogo Dictionary 329 NetLogo 4 0 User Manual gt 10 show subtract headings 355 5 gt 10 show subtract headings 180 0 gt 180 show subtract headings 0 180 gt 180 sum sum list Reports the sum of the items in the list show sum energy of turtles 7 prints the total of the variable energy from all the turtles T tan tan number Reports the tangent of the given angle Assumes the angle is given in degrees thickness thickness This is a built in link variable It holds a number that is the link s apparent size as a fraction of the patch size The thickness is 0 which means that regardless of patch size the links will always appear 1 pixel wide You can set this variable to change a link s thickness tick tick gt Advances the tick counter by one See also_ticks tick advance reset ticks tick advance tick advance number 330 NetLogo Dictionary NetLogo 4 0 User Manual Advances the tick counter by number The input
117. 97 aray AO A iaa 197 ten dc MAO om ES ives eis E E A AS 197 Table PrimItVeS e TA do les 197 table ice aii A A NAE 197 tablero Malta a tia 197 TAI as Coan toed a Le CORRER CN AO RD PORRA PER 197 tablas O ali 198 LADERA iii A A A Ada 198 Lale lei AAA A A A ai ia aa 198 ELERA e EE E E E A aio irc d 198 table Utica 198 table de pa o es a ER ea i ea RAN 198 TADOS DR PU eE N Aa 198 Sound EXTENSO assi cias io sae od cee do See each casted da el Tan an Soda baga cus inte 199 Usina the Sound EXIGHSION aid 199 MIDI SUppOr iris sas dectess escesudetels wees Gentes Ras E TALS qa Lage 199 PAI ES a tee E 199 A Metadata Cd l ole ee Os ad at ttl id SUAR E Sa tt ee 199 SOUNGNSTUIMENIS ssa gas srs radares Avs eben dcok ved ia puedo 200 sound play ArUM seese a EE NR dd Add daa aa 200 SOUNO an 00 e 200 sound play note later ea eens eens rre 200 soundiplay SOUNA ss Matinee aiie NA abba A lada 200 SOUNC play SOUND ANd WaAlt ee cee cece cece eect cette eter eter rre 201 sound play sound latet cece eee e eee ee teeter eee ttnn eeeeeeeeeeeeeeeeeneeegeeeeeeeeeeeeeeeeeeeeeeees 201 SOUNG Stan nOle eset tek PEE E a ea COL te a ae a 201 SOU SOON Oli AAA doa A re dan arena 201 sound stop instrument rn rr rr 202 SOUNO SHOD MUSI Cae 202 SOUNO NAMES LN ee nd 202 BJAO Ta 6 ESP RARO PRP A TA A A A A A 202 InStrUMENTS o Li Nope teed dada odias ates cea ds dat tedio 202 vii NetLogo 4 0 User M
118. A nessa gio ra Delicado sata do a cagada das 342 wilhout interrupton assiste nitani tarada datada dedo AR 343 WONG sds ars E eae MA AT TN 343 world width world height occoccccccccccccnncnoncnnnnnnnonnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnininiss 343 NetLogo 4 0 User Manual Table of Contents NetLogo Dictionary WIAD CONOM are ease GNR SR RNP RED o 344 WING PANDA DA q tute fea ita 344 OR ato doa RAR A ES Oe CRC O SC AR O O RA O DADA RPA UR ra 344 KOO lee saio schon hee nda are Um Cds en R Bak rae a ee Stole Laie a hes Meee ada Otek Sh a yo tanta Set 344 MO AAA DO GDA REL DONDE A Reads 345 eVects cutest a PLEN eae eee coe na GD Ne a Da a ba ae Ge tate Sah A od e II 345 MOO Lore ties Sexe E een Raio PRQ PESADA a ACESSOU POA SAR AS eee a RS AA ts 345 So E GOIS A OA EE P 345 AR ERA ete ORE RO RR SRD E E ou yaaa duns yan hab O RS RS T AMENO PDS SNS ND 345 xix XX NetLogo 4 0 User Manual What is NetLogo NetLogo is a programmable modeling environment for simulating natural and social phenomena It was authored by Uri Wilensky in 1999 and is in continuous development at the Center for Connected Learning and Computer Based Modeling NetLogo is particularly well suited for modeling complex systems developing over time Modelers can give instructions to hundreds or thousands of agents all operating independently This makes it possible to explore the connection between the micro level behavior of individuals and the m
119. Are there are any legal restrictions on use redistribution etc e Is the source code to NetLogo available e Do you offer any workshops or other training opportunities for NetLogo e Are there any NetLogo textbooks e Is NetLogo available in a Spanish version German version your language here version etc e Is NetLogo compiled or interpreted e Has anyone built a model of lt x gt e Are NetLogo models runs scientifically reproducible e Will NetLogo and NetLogo 3D remain separate Downloading e The download form doesn t work for me Can I have a direct link to the software e Downloading NetLogo takes too long Is it available any other way such as on a CD e downloaded and installed NetLogo but the Models Library has few or no models in it How can fix this e Can have multiple versions of NetLogo installed at the same time e I m on a UNIX system and can t untar the download Why e How do install NetLogo unattended e installed the without VM option now get an error message saying NetLogo can t find server dll Applets e tried to run one of the applets on your site but it didn t work What should do e Can make my model available as an applet while keeping the code secret e Can a model saved as an applet use import world file open and other commands that read files e When running my model as an applet get the following error java lang OutOfMemoryError Java heap space
120. Es LA RARE OND RR RS RAR MNE NR DR A 263 A A alia nata o aid 263 Til read characiers tis astmasa En 264 THESE AHN ui A A tt Dd 264 TIS SMOW tt it le esas 264 MES Cia ro acces cura este tee DS Os 265 TE A 265 ie A AA RARA E RS REAR RAR PD Sl AB 265 ATU PS A dete tec Daas Slogan a Dos do co at da ee Moto ale cpa as cotidiana a Dor a ea sets SAS 266 POO ras nica RR PE dA E O qe ea stam aaa 266 Ol ss E o id ad Ol A Sa a 266 TON OWING SANS CREA TO SNIS A ASPEN E NS EDNA NTE oe 266 E 266 TOWARDS le ARR gh le 267 MPL gs x areaan O 267 GE ES A ON 268 QIOD AIS ramais AA AA ded hatin Phe A ed ii aa 268 Y ee A aa A Co atoa An Do ERE ER eo do Pe ee O 268 hateh haich lt breedS gt imo eme da 268 NACI cs 269 A A a ium ame a A ii weed nao eee coat 269 PIGS Nise a scolds A a Ds e O A estos a ta DA da BA A AS ue 269 TC e CU TO 269 USO Asc a arith a ena AA alana he Aaa 270 NOM Sn eee ce ee da o DG god Gba a Ni aa E O a eRe 210 PSD as devs See ta UA quai bs voa dd ci dida datas SINO Cal ad oi dao EN DAR lia BEE EEEE 270 nubnei broadeasSt assis eai A la nieagda o Mave eh at alee le oa danosa legis Siaitiet tide 211 hubnet broadcasi viem screens anna rante teen AEEA naar anna nadas 211 hubbnet eEnter MeSSAGE ccccsccccccececssseeeneeeeeeeceeeeeeeeeaeeeeeeeeeesseeqaeeeeeeeeseeseeeeeeeeeeeees 271 NUbNEt EXit MESSAGE cccecccssnceccceeeessceenneeeeeceeeseeseceeeeeeeeeeeeesseneaaeeeeeeeessesensnseeeeeeees 27
121. Example Link Breeds Example Mouse Drag Multiple Example Hill Climbing Example Rolling Plot Example Ask Concurrent Example Ask Ordering Example Random Network Example Fully Connected Network Example Mobile Aggregation Example Wall Following Example Circular Path Example Profiler Example improved Code Examples Halo Example simplified using tie Intersecting Lines Example bugfix RGB and HSB Example now demonstrates RGB lists File Output Example new HubNet activity PANDA BEAR new HubNet code example Template improved HubNet activities Dice Stalagmite HubNet now verified Bug Hunters Camouflage now verified Root Beer Game now verified Disease Doctors now verified Minority Game e documentation 4 4 What s New new Transition Guide section in User Manual provides guidance on making models from previous versions work in NetLogo 4 0 new Syntax section in Programming Guide section of User Manual 10 NetLogo 4 0 User Manual new Applets section in User Manual e features most models now run somewhat faster 0 while results vary from model to model typical soeedup is around 1 5x 0 the speedup comes from an improved compiler that now partially compiles NetLogo code into Java byte code 4 links are now their own type of agent alongside turtles and patches this is useful for network models geometry models and much else new Link Shapes Editor lets you control the appearance of links logging allo
122. FAQ Frequently Asked Questions 215 NetLogo 4 0 User Manual e When tried loading my model as an applet get an error like java lang ClassFormatError Incompatible magic value Running e Can run NetLogo from a CD e Why is NetLogo so much slower when unplug my Windows laptop e How come NetLogo won t start up on my Linux machine e Can run NetLogo from the command line without the GUI e Does NetLogo take advantage of multiple processors cores e Can distribute NetLogo model runs across a cluster of computers e want to try HubNet Can 1 Usage e When move the speed slider all the way to the right why does my model seem to stop e How do change how many patches there are e Can use the mouse to paint in the view e How big can my model be How many turtles patches procedures buttons and so on can my model contain e Can import GIS data into NetLogo e Can have more than one model open at a time e Can change the choices in a chooser on the fly e Can divide the code for my model up into several files e How do show the legend in a plot Programming e How is the NetLogo language different from the StarLogo and StarLogoT languages How do convert my StarLogo or StarLogoT model to NetLogo e How does the NetLogo language differ from other Logos e How come my model from an earlier NetLogo doesn t work right e Why does my code have strange characters in it e Why do get a runt
123. I O primitives such as file open It is also possible to use external software to convert GIS data into a format that is easier to read from NetLogo than the original format This has been discussed on the NetLogo Users Group several times We encourage users interested in using NetLogo for GIS applications to share their questions and experiences with the group My model runs slowly How can speed it up Here s some ways to make it run faster without changing the code e Edit the forever buttons in your model and turn off the Force view update after each run checkbox This allows the view to skip frames which may speed up models which are graphics intensive See the Buttons section of the Programming Guide for a discussion of this e Use the freeze switch in the view control strip to freeze the view entirely Some models spend most of their time updating the view e If your model is using all available RAM on your computer then installing more RAM should help If your hard drive makes a lot of noise while your model is running you probably need more RAM e Use turtle size 1 1 5 or 2 as these sizes are cached by NetLogo In many cases though if you want your model to run faster you may need to make some changes to the code Usually the most obvious opportunity for speedup is that you re doing too many computations that involve all the turtles or all the patches Often this can be reduced by reworking the model so that it does le
124. IABLE FOR ANY DIRECT INDIRECT INCIDENTAL SPECIAL EXEMPLARY OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES LOSS OF USE DATA OR PROFITS OR BUSINESS INTERRUPTION HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY WHETHER IN CONTRACT STRICT LIABILITY OR TORT INCLUDING NEGLIGENCE OR OTHERWISE ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE Log4j For logging NetLogo uses the Log4j library The copyright and license for the library are as follows Copyright 1999 2005 The Apache Software Foundation Licensed under the Apache License Version 2 0 the License you may not use this file except in compliance with the License You may obtain a copy of the License at http Awww apache org licenses LICENSE 2 0 Unless required by applicable law or agreed to in writing software distributed under the License is distributed on an AS IS BASIS WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND either express or implied See the License for the specific language governing permissions and limitations under the License 8 Copyright Information What s New Feedback from users is very valuable to us in designing and improving NetLogo We d like to hear from you Please send comments suggestions and questions to feedback ccl northwestern edu and bug reports to bugs ccl northwestern edu Version 4 0 September 2007 e models 4 4 4
125. If you only want to remove only the points that the current plot pen has drawn use plot pen reset When a whole plot is cleared or when a pen is reset that doesn t just remove the data that has been plotted It also restores the plot or pen to its default settings as they were specified in the Interface tab when the plot was created or last edited Therefore the effects of such commands as 114 Programming Guide NetLogo 4 0 User Manual set plot x range and set plot pen color are only temporary Autoplotting By default all NetLogo plots have the autoplotting feature enabled This means that if the model tries to plot a point which is outside the current displayed range the range of the plot will grow along one or both axes so that the new point is visible In the hope that the ranges won t have to change every time a new point is added when the ranges grow they leave some extra room 25 if growing horizontally 10 if growing vertically If you want to turn off this feature edit the plot and uncheck the Autoplot checkbox At present it is not possible to enable or disable this feature only on one axis it always applies to both axes Temporary plot pens Most plots can get along with a fixed number of pens But some plots have more complex needs they may need to have the number of pens vary depending on conditions In such cases you can make temporary plot pens from code and then plot with them These pens are called t
126. Logo 3 0 142 Transition Guide NetLogo 4 0 User Manual allowed you to turn off such wrapping in the view without affecting the behavior of the model Since NetLogo 3 1 if you don t want the view to wrap you must make it so the world doesn t wrap using the new topology feature Making this change may require other changes to your model though See the Topology section of the Programming Guide for a thorough discussion of how to convert your model to take advantage of this new feature Transition Guide 143 NetLogo 4 0 User Manual 144 Transition Guide Applets Individual models can be run as Java applets inside a web browser Making and Displaying Applets You can create applets by choosing the Save As Applet option from the File Menu If your model is not saved in it s current state you will be prompted to save it again you will also be prompted to have an html file For applets to work the html file your model file and the file NetLogoLite jar must all be in the same directory You can copy NetLogoLite jar from the directory where you installed NetLogo Applets can read and write files on the web server If your applet requires additional files files it reads from imported images etc You will also need to upload those files to the server These files should appear in the same directory configuration relative to the model file as they appear on your computer Applets cannot read or write files on the user s computer only
127. Logo you could write see spot run alist of words but in NetLogo you must write see spot run a string or see spot run a list of strings instead e NetLogo s run command works on strings not lists since we have no word data type and does not permit the definition or redefinition of procedures e Control structures such as if and while are special forms not ordinary functions You can t define your own special forms so you can t define your own control structures NetLogo s run command is no help here e As in most Logos functions as values are not supported Most Logos provide similar if less general functionality though by allowing passing and manipulation of fragments of source code in list form NetLogo s capabilities in this area are presently limited A few of our 132 Programming Guide NetLogo 4 0 User Manual built in special forms use UCBLogo style templates to accomplish a similar purpose for example sort by length 21 lt length 22 string list In some circumstances using run and runresult instead is workable but unlike most Logos they operate on strings not lists Of course the NetLogo language also contains many additional features not found in most other Logos most importantly agents and agentsets Programming Guide 133 NetLogo 4 0 User Manual 134 Programming Guide Transition Guide Most models created in earlier versions of NetLogo also work in NetLogo 4 0 However some models w
128. MAX DVCOlcccoccocconcoconcconincnnccnnnonononencnnnonnenrannonnenrrnnennnnnnnnrenconananencannonnencannons 289 xiv NetLogo 4 0 User Manual Table of Contents NetLogo Dictionary Meana id ated 290 MM bata 290 Member ma A USA DS A De ASE 290 A ON 291 MIN O0NS 0 miis atea a nica tha 291 MIM PXCOPMIN PYVCOK aiii ii iaa MD a nada US atada apta E 291 AN 291 MODES A A A RR RE 292 MAUI ac dle 292 MOUSE INSIDG a ol risa 292 MOUSE SFE LOA a PEE A did 292 MOUSO XCOLT M USE YCOL aiin lidia 293 Maoh R A E E aa sed aT eed 293 MOVIE CANCEL ii si se a TA A T a N a aN 293 IMOWVIE ClOS e a EE EE EEIE E EE EEA TD DEEE E OA 293 movie grab view movie grab interfaCe oooccccccccononononccncnnnnnnnnnnnnnnnnnnnncnnnnnnononnnncnnnnnn 294 MOVIC SOt frAMO lAt cccccicecevseeeseecceeteeessecceueecetetesssucesvesestneuueueeceusvessateoeveebsieateaseees 294 IMOWIG SL sa asd ce a setts cet ene cwestan vtech LESS dat 294 MOVIE SIAUS A Bes ASL AeA dO RR A Te oh A De Re ee 294 my lt breeds gt MY lIDKS 2 0 eee ee eeeeeeeeeeeeeeeeceeeeeeeeeae eee eeeeeeeaeeaeeeeaeaeseaeseaeseeeseaeaeesseeneeee 295 my in lt breeds gt My ID lidkKS 00 ee cece eneee teeren tree rrer rneer nono non nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnos 295 my out lt breeds gt MYy OUtHIINKS 0ooooocoocccoccconcoonocononononononono nono nono nnnonnnnnnnnnnnnnnnnnnnonnnnnnos 295 MIS ao a da 296 NN RO O 296 INO bisection AI AAA A A NR SR 296 A Ea s LO Leo ar O RR 297 neigh
129. NetLogo in debugging your model For more information about Mathematica please visit the Wolfram Research web site What can I do with it Here are a few examples of what you can do with the Mathematica NetLogo link e Analyze your model in real time with seamless two way data conversion e Develop high quality custom visualizations of model data e Collect detailed simulation data across large multi dimensional parameter spaces e Rapidly develop interactive interfaces for exploring model behavior e Have direct access to patches and network data with built in functions Using the NetLogo Mathematica Link This section will very briefly introduce how to use the NetLogo Mathematica Link It will show you how to load the NetLogo Mathematica link package start NetLogo execute commands and retrieve data from NetLogo Loading the package Once the NetLogo Mathematica link is installed you can load the package by entering the following into your Mathematica notebook lt lt Net Logo Mathematica Link 183 NetLogo 4 0 User Manual Launching NetLogo from Mathematica To begin your NetLogo session in Mathematica type the following into your notebook NES lY yoti ner kogo joeicia P where your netlogo path is the directory that netlogo is located in Typically on a Macintosh computer this will be Applications NetLogo 4 0 Loading a model To load a model you must specify the full path of the model In this exampl
130. RGB Example model lets you experiment with the HSB and RGB color systems Color Swatches dialog The Color Swatches dialog helps you experiment with and choose colors Open it by choosing Color Swatches on the Tools Menu 0960 Color Swatches gray 5 8 7 a 8 9 9999 white 9 9999 A Preview red 15 19 9999 orange 25 29 29 9999 brown 35 39 19 9999 yellow 45 49 49 9999 green 55 59 59 9999 lime 65 09 9999 turquoise 75 79 79 9999 cyan 85 sky 95 blue 105 e E Z amp 2 amp amp amp 108 109 109 9999 violet 115 118 119 119 9999 magenta 125 128 129 129 9999 pink 135 138 139 139 9999 Copy selected color black M Numbers 10 0 50 0 1 Increment When you click on a color swatch or a color button that color will be shown against other colors In the bottom left the code for the currently selected color is displayed for example red 2 so you can copy and paste it into your code On the bottom right there are three increment options 1 0 5 and 0 1 These numbers indicate the difference between two adjacent swatches When the increment is 1 there are 10 different shades in each row when the increment is 0 1 there are 100 Programming Guide 93 NetLogo 4 0 User Manual different shades in each row 0 5 is an intermediate setting Ask NetLogo uses the ask command to give commands to turtles patches and links All code to be run by tu
131. a aa a he ah ES 218 Is the source code to NetLogo available csccccccccsssssesseeeeeeeeeeesssseeeeeeeeeesssssnaaees 218 Do you offer any workshops or other training opportunities for NetLogo 218 Are there any NetLogo textbooks2 erre nanaaaraarrrraanananea 219 Is NetLogo available in a Spanish version German version your language here VErSION OTG Mistas iodo og OSS A faia dd UA EA Eai ia Mi 219 Is NetLogo compiled or interpreted cccccccssecceeeeeseeeeeneeeeeeeeeessseneeeeeeeeeeeesesnnaaees 219 Has anyone built a model of ST ri ia 219 Are NetLogo models runs scientifically reproducible 219 Will NetLogo and NetLogo 3D remain separate erre 220 DOWN ias raia acetone age died TA aes E MEN eU aves 220 The download form doesn t work for me Can have a direct link to the software 220 Downloading NetLogo takes too long Is it available any other way such as ona CDA eat A te T eel oh I ER fi cle hse Eca SU eta 220 downloaded and installed NetLogo but the Models Library has few or no models Mit OWI CaM IAS ia asia ii 220 Can have multiple versions of NetLogo installed at the same time 221 I m on a UNIX system and can t untar the download Why2 neea 221 How do install NetLogo unattended cccccconnnonoccccnoconononononcncnnnnccnnnnanononnnnncccnannnnns 221 installed the without VM option and now get an err
132. a e e eraa dina 15 System Requirements A cena vans A AARAA Eae 17 System Requirements AppliCation cccccccccccecssssneeeeeeeeeeseseseneeeeeeesseseeseeeseeeeeeeesseseaaes 17 INMI Si SRE RR 17 MacOSX ces A A setae AE E ead era a dare ae ead 17 Other plato MS ui aid 17 System Requirements Saved AppletS oooooccccccnnnooconcccncnnncccnnnnnnnonononcnonnnanonnncnnnnnnnnnannnnnnnss 17 System Requirements 3D ViBW cccccononococnccccconononnnncncnnnnncncnnnnnnnnnnnnncncnnnnnnnnrnrrnnnnnnnnnnnnnnnos 17 Known ISSUES cosida 19 Known bugs all systems arara rena rena rena Ennan Ennn Ennn Ennen nannan 19 Language engine DUYQS cccccccccccncnonononononcnononononnnononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnniness 19 Other BUGS sia Sp ap 19 Windows only DUAS viii ei dat ees isi versie ae OM and wats Loanda 19 Macintosh only bugs A 20 Linux UNIX only DUaS comuna era ds dead dir o 20 Known issues with computer HubNet errar rene rena rear nennen En 20 Contacting Us Tutorial 3 Procedures NetLogo 4 0 User Manual Table of Contents Web Site Controlling the Model Bunton tadas Controlling speed Speed Slider ccooooooooccccccccnoonononccccnnnnconnnnannnonnnncnnnnnnns Adjusting Settings Sliders and Switches rea Gathering Information Plots and Monitors a Perspective DeMOS ococccccccccncnnncnoncnnncnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
133. a known seed for the NetLogo random number generator Note that you re also free to use the random seed command in your experiment s setup commands For more information on random seeds see the Random Numbers section of the Programmer s Guide You may specify values either by listing the values you want used or by specifying that you want to try every value within a given range For example to give a slider named number every value from 100 to 1000 in increments of 50 you would enter numb ce PEO ORS OME OO ON Or to give it only the values of 100 200 400 and 800 you would enter number 100 200 400 800 Be careful with the brackets here Note that there are fewer square brackets in the second example Including or not including this extra set of brackets is how you tell BehaviorSpace whether you are listing individual values or specifying a range Also note that the double quotes around the variable names are required You can vary as many settings as you want including just one or none at all Any settings that you do not vary will retain their current values Not varying any settings is useful if you just want to do many runs with the current settings What order you list the variables in determines what order the runs will be done in All values for a later variable will be tried before moving to the next value for an earlier variable So for example if you vary both x and y from 1 to 3 and x is listed first then the ord
134. a list Each value in the list can be any type of value a number or a string an agent or agentset or even another list Lists allow for the convenient packaging of information in NetLogo If your agents carry out a repetitive calculation on multiple variables it might be easier to have a list variable instead of multiple number variables Several primitives simplify the process of performing the same computation on each value in a list The NetLogo Dictionary has a section that lists all of the list related primitives Constant lists You can make a list by simply putting the values you want in the list between brackets like this set mylist 2 4 6 8 Note that the individual values are separated by spaces You can make lists that contain numbers and strings this way as well as lists within lists forexample 2 4 3 08 The empty list is written by putting nothing between the brackets like this Building lists on the fly If you want to make a list in which the values are determined by reporters as opposed to being a series of constants use the List reporter The 1i st reporter accepts two other reporters runs them and reports the results as a list If wanted a list to contain two random values might use the following code set random list list random 10 random 20 This will set random 1i st to a new list of two random integers each time it runs To make longer or shorter lists you can use the 1ist reporter with
135. acro level patterns that emerge from the interaction of many individuals NetLogo lets students open simulations and play with them exploring their behavior under various conditions It is also an authoring environment which enables students teachers and curriculum developers to create their own models NetLogo is simple enough that students and teachers can easily run simulations or even build their own And it is advanced enough to serve as a powerful tool for researchers in many fields NetLogo has extensive documentation and tutorials It also comes with a Models Library which is a large collection of pre written simulations that can be used and modified These simulations address many content areas in the natural and social sciences including biology and medicine physics and chemistry mathematics and computer science and economics and social psychology Several model based inquiry curricula using NetLogo are currently under development NetLogo can also power a classroom participatory simulation tool called HubNet Through the use of networked computers or handheld devices such as Texas Instruments graphing calculators each student can control an agent in a simulation Follow_this link for more information NetLogo is the next generation of the series of multi agent modeling languages that started with StarLogo It builds off the functionality of our product_StarLogoT and adds significant new features and a redesigned language and use
136. action gt added lt action gt lt event gt lt event logger org nlogo api Logger BUTTONS timestamp 1177341053679 a button is a type button gt BUTTONS pressed or info Sais RR E Anamnes released lt action gt released lt action gt lt releaseType gt once lt releaseType gt lt event gt SPEED SLIDER the speed slider info lt event logger org nlogo api Logger SPEED changes timestamp 1177341042202 level INFO type speed gt 176 Logging NetLogo 4 0 User Manual lt value gt 0 0 lt value gt lt event gt lt event logger org nlogo api Logger TURTL timestamp 1177341094342 level INFO turtles die or are type turtle gt born lt name gt turtle 1 lt name gt lt action gt born lt action gt lt breed gt TURTLES lt breed gt lt event gt lt event logger org nlogo api Logger LINKS timestamp 1177341094347 level INFO links die or are type link gt born lt name gt link 0 1 lt name gt lt action gt born lt action gt lt breed gt LINKS lt breed gt lt event gt How to configure the logging output The default logging configuration netlogo_logging xml looks something like this NetLogo defines 8 loggers all descend directly from the root logger which means unless you explicitly set the properties appender layout and output level in the configuration they will inherit them from the root In the default configuration th
137. add parentheses show 5 6 6 3 gt 32 show 5 6 6 3 gt 20 asin asin number Reports the arc sine inverse sine of the given number The input must be in the range 1 to 1 The result is in degrees and lies in the range 90 to 90 ask NetLogo Dictionary 241 NetLogo 4 0 User Manual ask agentset commands ask agent commands The specified agent or agentset runs the given commands ask turtles fd 1 all turtles move forward one step ask patches set pcolor red all patches turn red ask turtle 4 rt 90 7 only the turtle with id 4 turns right Note only the observer can ask all turtles or all patches This prevents you from inadvertently having all turtles ask all turtles or all patches ask all patches which is a common mistake to make if you re not careful about which agents will run the code you are writing Note Only the agents that are in the agentset at the time the ask begins run the commands ask concurrent ask concurrent ageniset commands The agents in the given agentset run the given commands using a turn taking mechanism to produce simulated concurrency See the Ask Concurrent section of the Programming Guide for details on how this works Note Only the agents that are in the agentset at the time the ask begins run the commands See also without interruption at points agentset at points x1 y1 x2 y2 Reports a subset of the given agentset that include
138. agentset show count turtles 7 prints the total number of turtles show count patches with pcolor red 7 prints the total number of red patches create ordered turtles cro create ordered lt breeds gt create ordered turtles number create ordered turtles number commands create ordered lt breeds gt number create ordered lt breeds gt number commands NetLogo Dictionary 249 NetLogo 4 0 User Manual Creates number new turtles New turtles start at position 0 0 are created with the 14 primary colors and have headings from 0 to 360 evenly spaced If the create ordered lt breeds gt form is used the new turtles are created as members of the given breed If commands are supplied the new turtles immediately run them commands This is useful for giving the new turtles a different color heading or whatever The new turtles are created all at once then run one at a time in random order ero 100 fa 10 7 makes an evenly spaced circle Note While the commands are running no other agents are allowed to run any code as with the without interruption command This ensures that if ask concurrent is being used the new turtles cannot interact with any other agents until they are fully initialized create lt breed gt to create lt breed gt from create lt breed gt with create link to create link from create link with create lt breed gt to turtle create lt breed gt to turtle commands create l
139. aken place in the world are visible to the user ask turtles set color red display ask turtles set color blue 7 turtles turn red then blue use of display forces 7 red turtles to appear briefly Note that display and no display operate independently of the switch in the view control strip that freezes the view See also no display distance distance agent Reports the distance from this agent to the given turtle or patch The distance to or a from a patch is measured from the center of the patch Turtles and patches use the wrapped distance around the edges of the world if wrapping is allowed by the topology and the wrapped distance is shorter ask turtles show max one of turtles distance myself each turtle prints the turtle farthest from itself distancexy NetLogo Dictionary 255 NetLogo 4 0 User Manual distancexy xcor ycor Reports the distance from this agent to the point xcor ycor The distance from a patch is measured from the center of the patch Turtles and patches use the wrapped distance around the edges of the world if wrapping is allowed by the topology and the wrapped distance is shorter if distancexy 0 0 gt 10 set color green 7 all turtles more than 10 units from 7 the center of the world turn green downhill downhill4 downhill patch variable downhill4 patch variable Moves the turtle to the neighboring patch with the lowest value for patch variable If
140. al randomness both runs will be identical Specifically how it works is the state of the random number generator is remembered before the commands run then restored afterwards If you want to run the commands with a fresh random state instead of the same random state that will be restored later you can begin the commands with random seed new seed The following example demonstrates that the random number generator state is the same both before the commands run and afterwards random seed 10 342 NetLogo Dictionary NetLogo 4 0 User Manual with local randomness print n values 10 random 10 7 prints 8 98 4245 47 9 print n values 10 random 10 7 prints 8 98 4245 47 9 without interruption without interruption commands The agent runs all the commands in the block without allowing other agents using ask concurrent to interrupt That is other agents are put on hold and do not run any commands until the commands in the block are finished Note This command is only useful in conjunction with ask concurrent In previous versions of NetLogo this command was often needed but in NetLogo 4 0 it is only ever needed if you are also using ask concurrent See also_ask concurrent word word value value2 word value Concatenates the inputs together and reports the result as a string show word tur tle gt turtle word a 6 gt a6 set directory c foo fish show word directo
141. alue of number show abs 7 gt y show abs 5 gt 5 acos acos number Reports the arc cosine inverse cosine of the given number The input must be in the range 1 to 1 The result is in degrees and lies in the range O to 180 all all agentset reporter Reports true if all of the agents in the agentset report true for the given reporter Otherwise false The reporter must report a boolean value for every agent either true or false otherwise an error occurs if all turtles color red show every turtle is red See also_any and condition and condition2 Reports true if both condition and condition2 are true Note that if condition is false then condition2 will not be run since it can t affect the result if pxcor gt 0 and pycor gt 0 NetLogo Dictionary 239 NetLogo 4 0 User Manual set pcolor blue the upper right quadrant of 7 patches turn blue any any agentset Reports true if the given agentset is non empty false otherwise Equivalent to count agentset gt 0 but more efficient and arguably more readable if any turtles with color red show at least one turtle is red Note nobody is not an agentset You only get nobody back in situations where you were expecting a single agent not a whole agentset If any gets nobody as input an error results See also all nobody approximate hsb approximate hsb hue saturation brightness Reports a numbe
142. ame of the turtle or link s current shape You can set this variable to change the shape New turtles and links have the shape default unless the a different shape has been specified using_set default shape Example ask turtles set shape wolf 7 assumes you have made a wolf 7 Shape in NetLogo s Turtle Shapes Editor ask links set shape link 1 7 assumes you have made a link 1 shape in the Link Shapes Editor See also set default shape shapes 324 NetLogo Dictionary NetLogo 4 0 User Manual shapes shapes Reports a list of strings containing all of the turtle shapes in the model New shapes can be created or imported from the shapes library or from other models in the Shapes Editor show shapes gt default airplane arrow box bug ask turtles set shape one of shapes show show value Prints value in the Command Center preceded by the calling agent and followed by a carriage return The calling agent is included to help you keep track of what agents are producing which lines of output Also all strings have their quotes included similar to_write See also print type and write See also output show show turtle st show turtle The turtle becomes visible again Note This command is equivalent to setting the turtle variable hidden to false See also hide turtle shuffle shuffle list Reports a new list containing the same items as the input lis
143. ance from the calling turtle or patch along the given absolute heading In contrast to patch left and ahead and patch right and ahead the calling turtle s current heading is not taken into account Reports 304 NetLogo Dictionary NetLogo 4 0 User Manual nobody if the patch does not exist because it is outside the world ask patch at heading and distance 90 1 set pcolor green 7 turns the patch 1 to the west of the calling patch He green See also patch patch at patch left and ahead patch right and ahead patch here patch here patch here reports the patch under the turtle Note that this reporter isn t available to a patch because a patch can just say self patch left and ahead patch right and ahead patch left and ahead angle distance patch right and ahead angle distance Reports the single patch that is the given distance from the calling turtle in the direction turned left or right the given angle in degrees from the turtle s current heading Reports nobody if the patch does not exist because it is outside the world If you want to find a patch in a given absolute heading rather than one relative to the current turtle s heading use patch at heading and distance instead ask patch right and ahead 30 1 set pcolor green 7 the calling turtle looks 30 degrees right of its ra current heading at the patch 1 unit away and turns Hs that patch green note that this might be the same i pa
144. anes Go eke Nat e Sat Gal ts Dae 253 AISO sir fom ccc ias ects ct Bek Raoni RO 253 O O ENO OR ACNE SPD O E E RD RR 254 directed link breed AA 254 displays a AREA AAA e RR A RR DEN e EI 255 distance a ada AA Rad e ee 255 dOIStANCO Vaina aia 255 downhill downhA occitano at 256 Us a Da alex Fnbusd aa 256 sa de dice Takata A cate ies OO ca nad og AGA o o da ae PE GR Rae TE 257 A S 257 SOTA NRP IE asic ea citi ces RSRS ESCADA GRAN SPAS RE A E RS SAE 257 A thet RE RENA A E RR tute sie 257 ENG Atenas are eh Ae BRO AR do O DADA eee eke o A A RA A 257 OTTO MOSS care 258 OO Vii ld AAA ai 258 O 258 export view export interface export output export plot export all plots OXPOM WONMG coin E A 258 SN O NE DIR DDS NO ORNE ane NENE RE IR Ded dee REDE OR 260 extraCt QD asi AAA Geisa S 260 Peck ERRO A nd DOR O UR DRE ADE RE RO AR ete es O NAA BS MEDE DOORS E RR A 260 TACO See gia Sol EabssDa c eC and RUN E Srta fes a 260 TACOR e e PRO ARE ARE CR ND NR DARI PURE SD ne 260 leandro Neel sie a Nake tee cleats egies ed Mat eas CR Di aa as 261 TIIG ClOS et kat 261 NetLogo 4 0 User Manual Table of Contents NetLogo Dictionary tle close alli fesse ERR eR RARO 0 A Sava veyed E SN AD 261 TIS ASIST ec wins chest ret ace oca ecos ds atedsautd skies eects una ett usted 262 THB HOXISTS Ena ee A EAS OEP RI Ui BS E A ASS CAB EE dA A IEE Sa 262 Tie TO Ea RS RR RR tile St RR RR AN RR E athe yale vanes teh ais RS 262 E E a pd SS a 262
145. anual Table of Contents SO O deen sveieadeasacceanatee 205 What is the GOGO Board terrena tan nonononanancno nana nano nana cano nanananes 205 Howto geta GoGo Bordado daa 205 Installing the GOGO Extension eee eerererereeenaaaranarereaaaaaaaananarereaaaaana 205 MacOS Xe tees eee ae i ee te ey ee Ie ee ala od 205 ET LO DORES RN Bee daw eae eed teeta grands we ence Serta st UR NNE PNR DRE TON 205 ELIMIIVES 22 a T eR E ee RO aS a e de 206 OOO COSA as fe casing cence visada Gas RREO chats voted haces de coven cooker SA EAD tua E CURSO CE 206 QOJO OPON ua 206 COCO ORs E aE RR aa 207 o oo o ON S SEEE E TE RR RR 207 gogo ouiput pori coast eee 207 OJO OMPI DO io 207 JOJO QUTPUT pPON TOVeISO comico sense maa odak ENK nnau 208 gogo output port that this Way ccccccccecccceceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeneetes 208 QOgO talk to QU pUI pPONES ccccccccconcconcnenenenenenenenennnenenennnnnnnrrrn rr rn rre 208 JOJO PINA sao cena ie ce na id ia se acusa duelam gado 208 OJO SOS PORN PIRES RR a DEN RR 209 gogo set output porit power ee aera ee eae eee cananeenaana na eeaeaaes 209 Profiler ExXIENSIOM ssa asdisossinesac ae feira ii 211 CavealS se sie dad tis Ath NA AE 211 USADO aa tt en O E ee CR Ea LD a 211 ERP IMES a A A CS aaa o dad 211 proteica ido 211 profiler exclUISiWS MO tad 211 DFORISMINCIISIVE TMG ria een nuit da aa deitada 212 A A tates
146. anual workspace dispose catch Exception ex ex printStackTrace In order to compile and run this either Net Logo jar or NetLogoLite jar from the NetLogo distribution must be in your classpath The latter jar is smaller but is only capable of headless operation not full GUI operation The lib directory containing additional required libraries must also be present When running in a context that does not support a graphical display the system property java awt headless must be true to force Java to run in headless mode HeadlessWorkspace automatically sets this property for you Since there is no GUI NetLogo primitives which send output to the command center or output area now go to standard output instead export world can still be used to save the model s state export view works for writing an image file with a snapshot of the otherwise invisible 2D view The report method is useful for getting results out of the model and into your Java code The files generated by export world include the contents of all plots You can also export the contents of plots individually using export plot You can make multiple instances of HeadlessWorkspace and they will operate independently on separate threads without interfering with each other When running headless there are some restrictions e The movie primitives are not available trying to use them will cause a Java exception e user primitives which que
147. ask turtle 2 tell the third one rt 90 si es Eo urn Fight ask patch 2 2 7 ask the patch at 2 2 set pcolor blue j to become blue ask turtle 0 7 ask the first turtle ask patch at 1 0 7 to ask patch to the east set pcolor red ii to become red ask turtle 0 tell the first turtle create link with turtle 1 make a link with the second ask link 0 1 7 tell the link between turtle 0 and 1 set color blue j to become blue 94 Programming Guide NetLogo 4 0 User Manual end Every turtle created has a who number The first turtle created is number 0 the second turtle number 1 and so forth The turt 1e primitive reporter takes a who number as an input and reports the turtle with that who number The patch primitive reporter takes values for pxcor and pycor and reports the patch with those coordinates The 1 ink primitive takes two inputs the who numbers of the two turtles it connects And the patch at primitive reporter takes offsets distances in the x and y directions from the first agent In the example above the turtle with who number 0 is asked to get the patch east and no patches north of itself You can also select a subset of turtles or a subset of patches or a subset of links and ask them to do something This involves a concept called agentsets The next section explains this concept in detail When you ask a set of agents to run more than one command each agent must finish before
148. at supports transparency alpha then all fully transparent pixels will be ignored Partially transparent pixels will be treated as opaque import pcolors rgb import pcolors rgb filename ig Reads an image file scales it to the same dimensions as the patch grid while maintaining the original aspect ratio of the image and transfers the resulting pixel colors to the patches The image is centered in the patch grid Unlike import pcolors the exact colors in the original image are retained The pcolor variable of all the patches will be an RGB list rather than an approximated NetLogo color The following image file formats are supported BMP JPG GIF and PNG If the image format supports transparency alpha then all fully transparent pixels will be ignored Partially transparent pixels will be treated as opaque import world import world filename Reads the values of all variables for a model both built in and user defined including all observer turtle and patch variables from an external file named by the given string The file should be in the format used by the export world primitive Note that the functionality of this primitive is also directly available from NetLogo s File menu When using import world to avoid errors perform these steps in the following order 1 Open the model from which you created the export file 2 Press the Setup button to get the model in a state from which it can be run 3 Import the file
149. at the functionality of these primitives is also available directly from NetLogo s File menu export world fire csv 7 exports the state of the model to the file fire csv 7 located in the NetLogo folder export plot Temperature c My Documents plot csv 7 exports the plot named 5 Temperature to the file plot csv located in 77 the C My Documents folder NetLogo Dictionary 259 NetLogo 4 0 User Manual export all plots c My Documents plots csv 77 exports all plots to the file plots csv 77 located in the C My Documents folder extract hsb extract hsb color Reports a list of three values in the range 0 to 255 representing the hue saturation and brightness respectively of the given NetLogo color in the range 0 to 140 not including 140 itself show extract hsb red gt 0 0090 0 809 0 843 show extract hsb cyan gt 0 5 0 571 0 769 See also approximate hsb approximate rgb extract rgb extract rgb extract rgb color Reports a list of three values in the range 0 to 255 representing the levels of red green and blue respectively of the given NetLogo color in the range 0 to 140 not including 140 itself show extract rgb red gt 0 843 0 196 0 161 show extract rgb cyan gt 0 329 0 769 0 769 See also approximate rgb approximate hsb extract hsb F face face agent Set the caller s heading towards agent If wrapping is allowed by the topology and the wrapped distance around t
150. ates e In the bottom of the patch monitor enter set pcolor blue and press return Typing a command in a turtle or patch monitor addresses only that turtle or patch You can also talk to a single patch from the Command Center e In the Command Center enter ask patch 11 4 set pcolor green and press return What s Next At this point you may want to take some time to try out the techniques you ve learned on some of the other models in the Models Library Tutorial 2 Commands 45 NetLogo 4 0 User Manual In_Tutorial 3 Procedures you can learn how to alter and extend existing models and build your own models 46 Tutorial 2 Commands Tutorial 3 Procedures This tutorial leads you through the process of building a complete model built up stage by stage with every step explained along the way Agents and procedures In Tutorial 2 you learned how to use the command center and agent monitors to inspect and modify agents and make them do things Now you re ready to learn about the real heart of a NetLogo model the Procedures tab You ve already used types of agents you can give commands to in NetLogo patches turtles links and the observer Patches are stationary and arranged in a grid Turtles move over that grid Links connect two turtles The observer oversees everything that s going on and does whatever the turtles patches and links can t do for themselves All four types of agents can run NetLogo commands
151. atics are good examples By using a different topology you get diffuse for free which was fairly difficult to do in the past Each patch diffuses and equal amount of the diffuse variable to each of its neighbors if it has fewer than 8 neighbors or 4 if you are using diffuse4 the remainder stays on the diffusing patch This means that the overall sum of patch variable across the world remains constant If you had special code to handle diffuse then you can remove it However if you want the diffuse matter to still fall off the edges of the world as it would on an infinite plane you still need to clear the edges each step as in the Diffuse Off Edges Example Links A link is an agent that connects two turtles The two turtles are called nodes The link is always drawn as a line between the two turtles Links do not have a location as turtles do they are not considered to be on any patch and you cannot find the distance from a link to another point There are two flavors of links undirected and directed A directed link is out of or from one node and into or to another node The relationship of a parent to a child could be modeled as a directed link An undirected link appears the same to both nodes each node has a link with another node The relationship between spouses or siblings could be modeled as an undirected link There is a global agentset of all links just as with turtles and patches You can create undirected links using the
152. aunch 1 cv o HKEY_LOCAL_MACHINE SOFTWARE Microsoft Windows CurrentVersion Uninstall NetLogo 3 0 2 DisplayName NetLogo 3 0 2 UninstallString STARGET_PATH S UninstallerData Uninstall NetLogo exe installed the without VM option and now get an error message saying NetLogo can t find server dll NetLogo uses a special option called the server VM which requires the JVM rather than just the JRE see the_requirements section for details Applets tried to run one of the applets on your site but it didn t work What should do Current versions of NetLogo require that your web browser support Java 1 4 1 or higher For more details about Java requirements see the Applet guide Some NetLogo applets may require more memory than the browser normally makes available See the memory section of the Applet guide for details on how to change the memory allocation Can make my model available as an applet while keeping the code secret No In order for the applet to operate the model file must be accessible also When you use Save as applet on the File menu the HTML page generated contains a link where the user can download the model file If you want you can remove that link Doing so will make it harder for the user to access the model file but not impossible Can a model saved as an applet use import world file open and other commands that read files Yes
153. ave strings In most situations where traditional Logo would use words we simply use strings instead For example in Logo you could write see spot run alist of words but in NetLogo you must write see spot run astring or see spot run a list of strings instead e NetLogo s run command works on strings not lists since we have no word data type and does not permit the definition or redefinition of procedures e Control structures such as if and while are special forms not ordinary functions You can t define your own special forms so you can t define your own control structures NetLogo s run command is no help here e As in most Logos functions as values are not supported Most Logos provide similar if less general functionality though by allowing passing and manipulation of fragments of source code in list form NetLogo s capabilities in this area are presently limited A few of our built in special forms use UCBLogo style templates to accomplish a similar purpose for example sort by length 21 lt length 22 string list In some circumstances using run and runresult instead is workable but unlike most Logos they operate on strings not lists Of course the NetLogo language also contains many additional features not found in most other Logos most importantly agents and agentsets How come my model from an earlier NetLogo doesn t work right See the_Lransition Guide section of the User Manual for help Why d
154. avior may change in a future version See the HubNet Authoring Guide for details and instructions hubnet enter message hubnet enter message Reports true if a new computer client just entered the simulation Reports false otherwise hubnet message source will contain the user name of the client that just logged on See the_HubNet Authoring Guide for details and instructions hubnet exit message hubnet exit message Reports true if a computer client just exited the simulation Reports false otherwise hubnet message source will contain the user name of the client that just logged off See the_HubNet Authoring Guide for details and instructions hubnet fetch message hubnet fetch message If there is any new data sent by the clients this retrieves the next piece of data so that it can be accessed by hubnet message hubnet message source and hubnet message tag This will cause an error if there is no new data from the clients See the HubNet Authoring Guide for details NetLogo Dictionary 271 NetLogo 4 0 User Manual hubnet message hubnet message Reports the message retrieved by hubnet fetch message See the HubNet Authoring Guide for details hubnet message source hubnet message source Reports the name of the client that sent the message retrieved by hubnet fetch message See the HubNet Authoring Guide for details hubnet message tag hubnet message tag Reports the tag that is associated with the data that was
155. ba 83 Includes Men ed ld 85 PEOgQrammiad QUIE lao 87 Agents a AAA AAA Alia 87 A A NN 88 A A 90 A RN 91 AS a A A A AAA 94 A O RN 95 BECAS va a ad DA do A la Ando oc A A A A ee 97 AA A O RR TE 98 BUON Si AA AA A eee ected ae ete 99 RN 101 MAMA rd 105 Random Numbers tii a oa 107 Auxiliary JON rd rai AAA Ai ad 108 OC AlMANGOMNESS a dia 108 TUE ADS nt A A A A cae 108 LARK SMADOS it a AS 109 TICECOUMOE ai AR A As a A E A ai 109 Wene a er te A RR NR DRC NR 110 FRACTHOMAl TICKS EE EA EEA a eds cate ate sete des sald a avant audio te e E 110 VIEW Updates us naaa as 110 COMUMUO US UO ATS S atada tomatoe aia E nd E 111 Tick based Updales ses sesmasegerizaa e E E Ea eE ae a Te eee dA Ta ISO da 111 CNOOSING A MAS cre saias a a os 112 PION ua ade 112 A E 115 OMPI A O a ARRARATS 116 EGO a ae a de oe eae O 117 NetLogo 4 0 User Manual Table of Contents Programming Guide MOVIES usura A ee A ee es ee Sa S as 118 Perspect qa toi creia Geass bea MEME TES ae steed daa selene ues ited bed 119 DIAWING eae eee aN Sia Aidan feats cua pans enon E RU EEE DEDO ES CR a 120 TODOIOG iii 121 LINKS ta A eet aaa ee enced et eet Pie bean AS 125 Ask Concu rent ssa du o Sent al tek Pedic teas ees pn ese ed e lines tei sta calo 128 SIG EE O e a anda Bea Mao fio Da aaa Pe Ome SR oP aE Je Pe 129 ESTADO NN 130 ACEITA Lo Lo ESPN Dated tenes RR ties thay a 130 dentro rapa ita da dedo q reed pad AEE ARE AR enced dt ias 130 CODE cee a Gs Tara ia ta EN a A
156. before do plots That s so if we write plotting code that uses the value of the tick counter it will see the new value not the old value In this tutorial we won t actually write any code like that but nonetheless it is generally good practice to call t ick after your agents have done their actions but before you plot Now that your model uses ticks you ll probably want to use the menu at the top of the Interface tab to change from continuous updates to tick based updates That means that NetLogo will only update that is redraw the view that is the display area where you see your agents between ticks never in the middle of a tick This makes your model run faster and ensures a consistent appearance since the updates will happen at consistent times See the Programming Guide for a fuller discussion of view updates Some more details First instead of always using 100 turtles you can have a variable number of turtles 64 Tutorial 3 Procedures NetLogo 4 0 User Manual e Make a slider variable called number using the monitor icon on the Toolbar and click on an open spot in the Interface Try changing the minimum and maximum values in the slider e Then inside of setup turtles instead of create turtles 100 you can type to setup turtles create turtles number ask turtles setxy random xcor random ycor end Test this change and compare how having more or fewer turtles initially affect the plots over time
157. bors NMeighbOrS4ocoooccccccococccccnonoooonnn noo ono nono nonnnn nono nono nono no nn rentrer nnnnnnnnnn nn nn nnnnnonnnnnnns 297 lt breed gt neighbors link NeighboES ooococccccinnccncccccccocccnccnnncnnnr rar rrn 297 lt breed gt neighbor link NeighboOr ccoooonconccccnnnccccnoncononononnccononannnnnnnnnononanannnnncncnnnnnn 298 netlogozapplet s srren siana e Sd rin 298 netlogo version sseeeeeeeee ee 298 KENE 11 a Mined ae E E a 298 NOA Made 299 DOVER savas AER DE RR DIS lao df 299 NO SIINKS A Aa dl es A DeL A UA I E Ad ds edo 299 NO PalcheS NN 300 MOE a RN IA E A ee ee 300 A oe ten estat an oh SO i er che Maa ec label aces ek ase ne a A DD ar as 300 NO Pa 88 Da A EEEE ELE DEE EERTE E E E ASE 300 RRA 300 A ae ade RNP DR CORREIO ania aaa SORO ARS 301 O A beatae eae eee oa Os E AAE TE AE La Sa a 301 OTe er danca cd RA EA nd DD A E A A SA A 301 A ENEE hese ae Sees LEA Oba SEN SS DESA eR LEA AE Ab Rd NIE eh cea AT 301 out lt breed gt neighbor Out limMk NeighborB ccccccconoonoconccncccnnnannnnccnnnoncnnnannnnccnnnnnnnn 302 out lt breed gt neighbors out link neighbors sereia 302 out lt breed gt to out link tQ si retserea ereta area eta nana nnnna conan 303 XV NetLogo 4 0 User Manual Table of Contents NetLogo Dictionary output print output show output type output writg cee ii 303 NP et as cca cathe patie RN 303 DLC INA ds A 303 patch a head chez
158. breed or two unbreeded links between a pair of agents nor more than one directed link of the same breed in the same direction between a pair of agents You can have two directed links of the same breed or two unbreeded links between a pair if they are in opposite directions Layouts As part of the experimental network support we have also added several different primitives that will help you to visualize the networks The simplest is Layout circle which evenly spaces the agents around the center of the world given a radius layout radial is a good layout if you have something like a tree structure though even if there are some cycles in the tree it will still work though as there are more and more cycles it will probably not look as good layout radial takes a root agent to be the central node places it at 0 0 and arranges the nodes connected to it in a concentric pattern Nodes one degree away from the root will be arranged in a circular pattern around the central node and the next level around those nodes and so on layout radial will attempt to account for asymmetrical graphs and give more space to branches that are wider layout radial also takes a breed as an input so you use one breed of links to layout the network and not another 126 Programming Guide NetLogo 4 0 User Manual Given a set of anchor nodes layout tutte places all the other nodes at the center of mass of the nodes it is linked to The anchor set is automaticall
159. but only to read files that are stored in the same directory on your web server as the HTML and model files Applets cannot read files on the user s computer only the web server 222 FAQ Frequently Asked Questions NetLogo 4 0 User Manual When running my model as an applet get the following error java lang OutOfMemoryError Java heap space The Java Plug In is not allocating sufficient space to run the model Details on how big a model can be in NetLogo can be found here You will need to increase the amount of memory available to the Java Plug In See the instructions here When I tried loading my model as an applet get an error like java lang ClassFormatError Incompatible magic value If your web server returns custom error messages in response to requests for non existent pages it must also return a status code of 404 Not Found otherwise NetLogo thinks the following data is what it requested and tries to read it as such This happens even if all the files required to run the applet are present If you don t have control over the error messages on your web server you can use the following as a workaround e Create a directory named META INF in the same directory as the applet files e Create a subdirectory of META INF called services e Create a file called org apache commons logging LogFactory in the services subdirectory e Add the following line to org apache commons logging LogFactory org apa
160. ccessfully use the 3D view Try it and see Some systems can use the 3D window but can t switch to 3D fullscreen mode It depends on the graphics card and controller For example the ATI Radeon IGP 345 and Intel 82845 probably will not work System Requirements 17 18 NetLogo 4 0 User Manual System Requirements Known Issues If NetLogo malfunctions please send us a bug report See the Contacting Us section for instructions Known bugs all systems Language engine bugs e The array and table extensions are only partially compatible with the importing worlds feature When you export a NetLogo world using the export world command or Export World menu item arrays and tables are exported by value This means that if you have the same array or table stored in more than one location then when it is exported and re imported there will now be a distinct arrays or tables in each of the places the original array or table appeared These duplicates will initially contain the same values but if one duplicate is altered the others will not change e Export World does not save the state of any open files used by the file primitives If you have a file open export the world and then import that world into NetLogo you will need to re open that file before resuming the run e A bug in Java causes patch colors imported using import pcolors to be brighter than the original if the original image has a grayscale palette To work around t
161. ch variables They hold the x and y coordinate of the patch They are always integers You cannot set these variables because patches don t move pxcor is greater than or equal to min pxcor and less than or equal to max pxcor similarly for pycor and min pycor and max pycor All patch variables can be directly accessed by any turtle standing on the patch See also_xcor ycor R random random number If number is positive reports a random integer greater than or equal to O but strictly less than number If number is negative reports a random integer less than or equal to O but strictly greater than number If number is zero the result is always 0 as well 310 NetLogo Dictionary NetLogo 4 0 User Manual Note In versions of NetLogo prior to version 2 0 this primitive reported a floating point number if given a non integer input This is no longer the case If you want a floating point answer you must now use random float instead show random 3 7 prints 0 1 or 2 show random 3 7 prints 0 lt 17 or 2 show random 3 5 PEINES Ops dy 25 OF 3 See also random float random float random float number If number is positive reports a random floating point number greater than or equal to O but strictly less than number If number is negative reports a random floating point number less than or equal to O but strictly greater than number If number is zero the result is always 0 show random float 3
162. che commons logging impl LogFactoryImpl Note that all the directory and file names are case sensitive and should be created exactly as written Running Can run NetLogo from a CD Yes NetLogo runs fine on a read only file system Why is NetLogo so much slower when I unplug my Windows laptop Your computer is switching to power saving mode when unplugged It s normal for this to reduce speed a little but unfortunately there is a bug in Java that drastically slows down Swing applications including NetLogo One workaround is to change the power settings on your computer so it doesn t go into power saving mode when you unplug it If you do this your battery won t last as long Another workaround is to run NetLogo with an option recommended by Sun by editing the NetLogo lax file found in the NetLogo directory under Program Files on your hard drive unless you installed NetLogo in a different location Edit this line lax nl java option additional Djava ext dirs server Dsun java2d noddraw true FAQ Frequently Asked Questions 223 NetLogo 4 0 User Manual and add Dsun java2d ddoffscreen false at the end of the last line You can see the details of the Java bug and vote for Sun to fix it_here How come NetLogo won t start up on my Linux machine Ideally any Java runtime version 1 4 1 or greater will run NetLogo However some Java implementations do not support features which NetLogo uses such as Java2D and Swing
163. cible Yes NetLogo s agent scheduling algorithms are deterministic and NetLogo always uses Java s strict math library which gives bit for bit identical results regardless of platform But keep the following cautions in mind e If your model uses random numbers then in order to get reproducible behavior you must use the random seed command to set the random seed in advance so that your model will FAQ Frequently Asked Questions 219 NetLogo 4 0 User Manual receive the exact same sequence of random numbers every time Remember that agentsets are always in random order so anything you do with agentsets uses random numbers e If your model uses the every or wait Commands in such a way that affects the outcome of the model then you may get different results on different computers or even on the same computer since the model may run at a different speed Such models are rare These two commands are common but using them in a way that affects the outcome is not e In order to reproduce model runs exactly you must be using the exact same version of NetLogo The details of the agent scheduling mechanism and the random number generator may change between NetLogo versions and other changes bugfixes in the engine language changes and so forth may also affect the behavior of your model Then again they may not e We have expended every effort to make NetLogo model runs fully reproducible but of course this can never truly be an iron
164. create 1ink with and create links with commands and directed links using the create link to create links to create link from and create links from commands Once the first link has been created directed or undirected all unbreeded links must match links also support breeds much like turtles which will be discussed shortly it s impossible to have two unbreeded links where one is directed and the other is Programming Guide 125 NetLogo 4 0 User Manual undirected A runtime error occurs if you try to do it If all unbreeded links die then you can create links of that breed that are different in flavor from the previous links In general primitives that work with directed links have in Undirected ones either omit these or use with out to and from in their names Link breeds like turtle breeds allow you to define different types of links in your model Link breeds must either be directed or undirected unlike unbreeded links this is defined at compile time rather than run time You declare link breeds using the keywords undirected 1ink breed and directed 1ink breed Breeded links can be created using the commands create lt breed gt with and create lt breeds gt with for undirected breeds and the commands create lt breed gt to create lt breeds gt to create lt breed gt from and create lt breeds gt from for directed links There cannot be more than one undirected link of the same
165. cs will remain the same in future versions of NetLogo Tie Tie connects two turtles so that the movement of one turtles affects the location and heading of another Tie is a property of links so there must be a link between two turtles to create a tie relationship When a link s tie mode is set to fixed or free end1 and end2 are tied together If the link is directed end1 is the root agent and end2 is the leaf agent That is when end1 moves using fa jump setxy etc end2 also moves the same distance and direction However when end2 moves it does not affect end1 Programming Guide 129 NetLogo 4 0 User Manual If the link is undirected it is a reciprocal tie relationship meaning if either turtle moves the other turtle will also move So depending on which turtle is moving either turtle can be considered the root or the leaf The root turtle is always the turtle that initiates the movement When the root turtle turns right or left the leaf turtle rotates around the root turtle the same amount as if a stiff were attaching the turtles When tie mode is set to fixed the heading of the leaf turtle changes by the same amount If the tie mode is set to free the heading of the leaf turtle is unchanged The tie mode of a link can be set to fixed using the tie command and set to none meaning the turtles are no longer tied using untie to set the mode to free you need to set tie mode free Code Example Tie System Examp
166. ctionary ABCDEFGHIJLMNOPRSTUVWXY Categories Turtle Patch Agentset Color Control Logic World Perspective Input Output Files List String Math Plotting Links Movie System HubNet p margin left 1 5em h3 font size 115 h4 font size 100 margin left 1 5em background white Categories This is an approximate grouping Remember that a turile related primitive might still be used by patches or the observer and vice versa To see which agents turtles patches links observer can actually run a primitive consult its dictionary entry Turtle related back bk lt breeds gt at lt breeds gt here lt breeds gt on can move clear turtles ct create lt breeds gt create ordered lt breeds gt create ordered turtles cro create turtles crt die distance distancexy downhill downhill4 dx dy face facexy forward fd hatch hatch lt breeds gt hide turtle ht home inspect is lt breed gt is turtle jump left It move to myself nobody no turtles of other patch ahead patch at patch at heading and distance patch here patch left and ahead patch right and ahead pen down pd pen erase pe pen up pu random xcor random ycor right rt self set default shape set line thickness setxy shapes show turtle st sprout sprout lt breeds gt stamp stamp erase subject subtract headings tie towards towardsxy turtle turtle set turtles turtles at turtles here
167. d automatically 7 Change their shape to dog See also_shape set histogram num bars set histogram num bars number Set the current plot pen s plot interval so that given the current x range for the plot there would be number number of bars drawn if the histogram command is called See also histogram __set line thickness set line thickness number Specifies the thickness of lines and outlined elements in the turtle s shape The default value is 0 This always produces lines one pixel thick Non zero values are interpreted as thickness in patches A thickness of 1 for example produces 322 NetLogo Dictionary NetLogo 4 0 User Manual lines which appear one patch thick It s common to use a smaller value such as 0 5 or 0 2 Lines are always at least one pixel thick This command is experimental and may change in later releases set plot pen color set plot pen color number Sets the color of the current plot pen to number set plot pen interval set plot pen interval number Tells the current plot pen to move a distance of number in the x direction during each use of the plot command The plot pen interval also affects the behavior of the histogram command set plot pen mode set plot pen mode number Sets the mode the current plot pen draws in to number The allowed plot pen modes are e line mode the plot pen draws a line connecting two points together e 1 bar mode the plot pen draws a bar of width pl
168. d be interpreted in standard mathematical notation namely as sin x 1 e The and and or reporters are special forms not ordinary functions and they short circuit that is they only evaluate their second input if necessary e Procedures can only be defined in the Procedures tab not interactively in the Command Center e Reporter procedures that is procedures that report return a value must be defined with to report instead of to The command to report a value from a reporter procedure is report not output 228 FAQ Frequently Asked Questions NetLogo 4 0 User Manual e When defining a procedure the inputs to the procedure must be enclosed in square brackets e g to square x e Variable names are always used without any punctuation always foo never foo or foo To make this work instead of amake command taking a quoted argument we supply a set special form which does not evaluate its first input As a result procedures and variables occupy a single shared namespace The last three differences are illustrated in the following procedure definitions most Logos NetLogo to square x to report square x output x x report x x end end Deeper differences e NetLogo is lexically scoped not dynamically scoped e NetLogo has no word data type what Lisp calls symbols Eventually we may add one but since it is seldom requested it may be that the need doesn t arise much in agent based modeling We do h
169. d file open needs to be called before this command can be used See also file print filetype and file write file type file type value Prints value to an opened file not followed by a carriage return unlike file print and file show The lack of a carriage return allows you to print several values on the same line The calling agent is not printed before the value unlike file show Note that this command is the file i o equivalent of type and file open needs to be called before this command can be used See also file print fle show and file write file write file write value This command will output value which can be a number string list boolean or nobody to an opened file not followed by a carriage return unlike file print and file show The calling agent is not printed before the value unlike file show Its output also includes quotes around strings and is prepended with a space It will output the value in such a manner that file read will be able to interpret it Note that this command is the file i o equivalent of write and_file open needs to be called before this command can be used file open locations txt ask turtles file write xcor file write ycor See also_file print fle show and file type filter filter reporter list Reports a list containing only those items of list for which the boolean reporter is true in other words the items satisfying the given condition In
170. d in many parts of the program H hatch hatch lt breeds gt hatch number commands hatch lt breeds gt number commands This turtle creates number new turtles Each new turtle is identical to and at the same location as its parent The new turtles then run commands You can use the commands to give the new turtles different colors headings locations or whatever The new turtles are created all at once then run one at a time in random order If the hatch lt breeds gt form is used the new turtles are created as members of the given breed Otherwise the new turtles are the same breed as their parent Note While the commands are running no other agents are allowed to run any code as with the without interruption command This ensures that if ask concurrent is being used the new turtles cannot interact with any other agents until they are fully initialized hatch 1 1t 45 fd 1 this turtle creates one new turtle and the child turns and moves away hatch sheep 1 set color black 7 this turtle creates a new turtle 7 Of the sheep breed See also create turtles sprout 268 NetLogo Dictionary NetLogo 4 0 User Manual heading heading A This is a built in turtle variable It indicates the direction the turtle is facing This is a number greater than or equal to 0 and less than 360 0 is north 90 is east and so on You can set this variable to make a turtle turn See also_right left dx dy
171. data structure Arrays are useful when you need a collection of values whose size is fixed You can quickly access or alter any item in an array if you know its position Tables are useful when you need to do associate values with other values For example you might make a table of words and their definitions Then you can look up the definition of any word Here the words are the keys You can easily retrieve the value for any key in the table but not vice versa How to use Both extensions come preinstalled To use the array extension in your model add a line to the top of your procedures tab extensions array To use the table extension in your model add a line to the top of your procedures tab extensions table You can use both extensions in the same model if you want as follows extensions array table If your model already uses other extensions then it already has an extensions line in it so just add array and or table to the list For more information on using NetLogo extensions see the Extensions Guide Limitation on table keys Table keys may only be strings numbers booleans or lists Lists may be arbitrarily nested lists as long as all the items inside are strings numbers or booleans Array example let a array from list n values 5 0 print a Array and Table Extensions 195 NetLogo 4 0 User Manual gt array 0 0 0 0 0 print array length a gt 5 foreach n values 5 array set a
172. database programs such as Excel You can also export a plot by Tutorial 1 Models 31 NetLogo 4 0 User Manual control clicking Mac or right clicking Windows it and choosing Export from the popup menu Monitors Monitors are another method of displaying information in a model Here are the monitors in Wolf Sheep Predation time ticks sheep wolves grass 4 0 0 0 0 The monitor labeled time ticks tells us how much time has passed in the model The other monitors show us the population of sheep and wolves and the amount of grass Remember the amount of grass is divided by four to keep the plot from getting too tall The numbers displayed in the monitors update continuously as the model runs whereas the plots show you data from the whole course of the model run Note that NetLogo has also another kind of monitor called agent monitors These will be introduced in Tutorial 2 Controlling the View If you look at the interface tab you ll see a strip of controls along the top edge in the toolbar These controls change various aspects of the view Let s experiment with the effect of these controls e Press setup and then go to start the model running e As the model runs move the speed slider to the left What happens This slider is helpful if a model is running too fast for you to see what s going on in detail e Move the speed slider to the middle e Try moving the speed slider to the rig
173. dean teeta AAA can aaa na dra 304 E AN 304 patch at heading and distance nin r rre 304 O A 305 patch left and ahead patch right and ahead seen 305 DANA A A AA AAA pa cas 305 DA ii A AA A AAA Pini Ad A leaned 306 NS 306 10100 ii A TE EI U NE OURO OO PURE ERES REDE DURE DDR DR 306 pen down pd pen erase pe pen up PDlbicccincnnnccnnccnncnnncnnncnannnnnn narra 306 DEN MOdES der sines eram a A DS O a 307 DPONESSIZO e EE o a EUA E E cla du RA dO As DRA anaes 307 plabel ssa aires ed ancas ca ia 307 DlaBel COlO SRP un ran AAA AA a SRP TS 307 oloi PARRA EE NE dio 308 DIOISN AMES a CE Ega di dora wanes 308 DIODOS Rai AAA ad 308 plot pen down plOt DeOO Up oocccncccncccncccnncnnnnnnnnnn cnn rre 308 plol pen reSCL iii A nes 308 DI ia Notas 309 plot x min plot x max plot y min plot y max sessao 309 DOS Mii o A AE atria castes 309 A O SNC 309 CSUN NEE PR Ae Se ace A IAS 310 PXCOr 011010 occccn ddr 310 eR i A NT 310 randon A O O 310 cla O CADA ed OOE E E ara Re seek ida 311 random exponential random gamma random normal random poisson 311 random pXCOr ane a e 0 4 ibe 010 ee 312 random SeCA ss od 312 random xcor t lal0 0 gee 010 eee 313 o assets E E A T T 313 EE ELETE ER TEE NA E EE RR NRO RARE 313 LEMAINA Co pear O df RT E 314 FEMOV ER o ee ee Bie aie LEE ee eh ae aoe o Led Are sees 0d 315 FEMOVE GUPIICATES iii acia ea dantas 315 remove ITEM sic
174. deco sche LES ee dd 246 A eats e act dk es eek RRS eA Roe aN tes geet E a SR ade LAE ok nara ta 246 xi NetLogo 4 0 User Manual Table of Contents NetLogo Dictionary xii CAN MOVE ss cote PNAD A SAN RO O RS RR eee 246 CANCUN os osso meiasirora dosent vs da ia 246 COINA ris sak crer O A A A 247 clear al Cas ias iza ee ese sie te Ste ee LON ae SOON TESE ENGESA DS LES SUMA a ag T 247 Cle ar all PlOtS tati iaa 247 Cle ar GlAWING OA ceder teint oe eine ine tended ai SUA A ARA atone 247 CIS ARS NIAKS siso a A audi 247 lO OU DU o Dart dA a S 248 CIE A ACHES CD Eanes sanidade dade io aa EUROS A Ene dan Dana sanada ra pes pa caves 248 ClO Al A RE 248 clearalurtles Clica a de A do MEO a da At 248 6 0 0 AAEE a RR 249 COS Rosita A A sel a eee etn e q es 249 COUT sates CA aid lee ee ain Aneel a E all A ii ae Oe Nate Ne el A aq cara et Nae lah SNe a tae le 249 create ordered turtles cro create ordered lt breedS gt ccccooonccncccoocononncnconcnnoncnnnnnnnonos 249 create lt breed gt to create lt breed gt from create lt breed gt with create link to create link from create link with erre cerrre a rrrreana 250 create turiles crt Create lt bDreedS gt ooccccncccnnnncnnnoncnannononanonanan ona nan o serena rena een canon 251 create temporary plOl PON ccccccccnccononennneneneneneneneneninennnnnnnrrrn rre 252 A A A A E A A 253 Aate and tiM es oct iman un A AAA a Bs een ed cei 253 CNES A E o e e tae RR c
175. del First use the movie start command to start a new movie The filename you provide should end with mov the extension for QuickTime movies To add a frame to your movie use either movie grab view Of movie grab interface depending on whether you want the movie to show just the current view or the entire Interface tab In a single movie you must use only one movie grab primitive or the other you can t mix them When you re done adding frames use movie close 118 Programming Guide NetLogo 4 0 User Manual 77 export a 30 frame movie of the view setup movie start out mov movie grab view show the initial state repeat 30 go movie grab view movie close By default a movie will play back at 15 frames per second To make a movie with a different frame rate callmovie set frame rate with a different number of frames per second You must set the frame rate after movie start but before grabbing any frames To check the frame rate of your movie or to see how many frames you ve grabbed call movie status which reports a string that describes the state of the current movie To throw away a movie and delete the movie file call movie cancel Code Example Movie Example NetLogo movies are exported as uncompressed QuickTime files To play a QuickTime movie you can use QuickTime Player a free download from Apple Since the movies are not compressed they can take up a lot of disk space You will probably wa
176. del now Some turtles die off some new turtles are created hatched and some grass grows back This is exactly what we set out to do If you continue to watch your monitors in your model you will see that the count turtles and green patches monitors both fluctuate Is this pattern of fluctuation predictable Is there a relationship between the variables It d be nice if we had a easier way to track the changes in the model behavior over time NetLogo allows us to plot data as we go along That will be our next step Plotting To make plotting work we ll need to create a plot in the Interface tab and set some settings in it Then we ll add one more procedure to the Procedures tab which will update the plot for us 60 Tutorial 3 Procedures NetLogo 4 0 User Manual Let s do the Procedures tab part first e Change setup to call the new procedure do plot s which we re about to add to Setup clear all setup patches setup turtles do plots end e Also change go to call the do plots procedure TOGO move turtles eat grass reproduce check death regrow grass do plots end e Now add the new procedure What we re plotting will be be the number of turtles and the number of green patches versus time At each time step a single run through the go procedure these values are added to the plot to do plots set current plot Totals set current plot pen turtles plot count turtles set current plot pen grass plot count patc
177. disk image into the Applications folder Windows There are two possible approaches NetLogo uses InstallAnywhere which has a silent install mode You have to make properties file with the same name as the installer executable and it should contain the following with values to reflect your preferences and the version you are installing USER INSTALL DIR programs NetLogoX Y INSTALLER_UI silent Another approach is to install NetLogo and then copy the resulting directory onto other machines Unfortunately NetLogo will not appear in the Start menu nor will nlogo files will not start NetLogo automatically when you double click them However Anders Martinusen writes Also found that is possible to export a few keys from the windows registry into a reg file This file can then be pushed out on the target machines along with the files This will solve the issue about double clicking the nlogo files It also gives the possibility to later on uninstall the program from the Control Panel The content of the reg file is HKEY_CLASSES_ROOT nlogo Net LogoModelFile FAQ Frequently Asked Questions 221 NetLogo 4 0 User Manual KEY_CLASSES_ROOT Net LogoModelFile NetLogo model file O o KEY CLASSES ROOTNYNetLogoModelFileNDefaultIcon STARGET PATHS A Model icon ico 0 m7 KEY_CLASSES_ROOT Net LogoModelFile shell open command STARGET_PATH S NetLogo 3 0 2 exe l
178. dures tab to change the indentation level of your code or add and remove semicolons which mark comments from sections of code 84 Interface Guide NetLogo 4 0 User Manual For more information about writing procedures read_Tutorial 3 Procedures and the Programming Guide Includes Menu When you add the__includes keyword to a model a menu to the right of the procedures menu appears This is the includes menu which lists all the NetLogo source files nls included in this file either nlogo or nls 2 Y Procedures w Includes w Find Checl __includes foo nls J You can click on the file names in the menu to open a new tab containing that file or you can open new files or files in the file system using the other New Source File and Open Source File respectively New Source File Open Source File Once you ve opened new tabs you can navigate them similarly to the other tabs They are accessible from the Tabs menu and you can use the keyboard to move from tab to tab Command number on Mac Control number on other operating systems Interface 1 titled Information 382 irocedures_Mroomis Procedures 363 foo nis 324 lim il Interface Guide 85 86 NetLogo 4 0 User Manual Interface Guide Programming Guide The following material explains some important features of programming in NetLogo The Code Example models mentioned throughout can be found in the Code Exam
179. e if there is still more to do After reading ahead for a couple of paragraphs you should then go back over the directions to see if there is any step you might have missed Making the go button Now make a button called go Follow the same steps you used to make the setup button except e For Commands enter go instead of setup e Check the forever checkbox in the edit dialog setup aA Button Agent s Observer HJ M Forever Commands 90 Display name Action key The forever checkbox makes the button stay down once pressed so its commands run over and over again not just once e Then add a go procedure to the Procedures tab to go move turtles end But what is move turt les ls it a primitive in other words built in to NetLogo like clear a11 is No it s another procedure that you re about to add So far you have introduced two procedures that you added yourself setup and go 50 Tutorial 3 Procedures NetLogo 4 0 User Manual e Add the move turtles procedure after the goprocedure Lo do move turtles end to move turtles ask turtles right random 360 forward 1 Note there are no spaces around the dash in move turtles In Tutorial 2 we used red 2 with spaces in order to subtract two numbers but here we want move turtles without spaces The combines move and turtles into a single name Here is what each command in the move turtles procedure does ea
180. e 117 NetLogo 4 0 User Manual When you are finished using a file you can use the command file close to end your session with the file If you wish to remove the file afterwards use the primitive i le delete to delete it To close multiple opened files one needs to first select the file by using i1e open before closing it 7 Open 3 files file open myfilel txt file open myfile2 txt file open myfile3 txt Now close the 3 files file close file open myfile2 txt file close file open myfilel txt file close Or if you know you just want to close every file you can use file close all Two primitives worth noting are file write and file read These primitives are designed to easily save and retrieve NetLogo constants such as numbers lists booleans and strings file write will always output the variable in such a manner that file read will be able to interpret it correctly file open myfile txt Opening file for writing ask turtles file write xcor file write ycor file close file open myfile txt Opening file for reading ask turtles setxy file read file read file close Code Examples File Input Example and File Output Example Letting the user choose The user directory user file and user new file primitives are useful when you want the user to choose a file or directory for your code to operate on Movies This section describes how to capture a QuickTime movie of a NetLogo mo
181. e Command Center the text shown below Command Center Wi Clear observer gt ask patches set pcolor yellow observer gt ask turtles E set color brown J Vv 38 Tutorial 2 Commands NetLogo 4 0 User Manual Was the result what you expected Your View should have a yellow background with a line of brown cars in the middle The NetLogo world is a two dimensional world that is made up of turtles patches and an observer The patches create the ground in which the turtles can move around on and the observer is a being that oversee everything that is going on in the world For a detailed description and specifics about this world refer to the NetLogo Programming Guide In the Command Center we have the ability to give the observer a command the turtles a command or the patches a command We choose between these options by using the popup menu located in the bottom left corner of the Command Center You can also use the tab key on your keyboard to cycle through the different options e In the Command Center click on the observers in the bottom left corner Command Center Clear observer gt ask patches set pcolor yellow observer gt ask turtles set color brown obser R observer rs rn patches links e Choose turtles from the popup menu e Type set color pink and press return e Press the tab key until you see patches gt in the bottom left corner e Type set pcolor
182. e a directory user file user file Opens a dialog that allows the user to choose an existing file on the system It reports a string with the absolute file path or false if the user cancels file open user fil j Assumes the user will choose a file user new file user new file Opens a dialog that allows the user to choose a location and name of a new file to be created It reports a string with the absolute file path or false if the user cancels file open user new fil j Assumes the user will choose a file Note that this reporter doesn t actually create the file normally you would create the file using file open as in the example If the user chooses an existing file they will be asked if they wish to replace it or not but the the reporter itself doesn t cause the file to be replaced To do that you would use file delete user input user input value Reports the string that a user types into an entry field in a dialog with title value value may be of any type but is typically a string show user input What is your name 338 NetLogo Dictionary NetLogo 4 0 User Manual user message user message value Opens a dialog with value displayed as the message value may be of any type but is typically a string user message word There are count turtles turtles user one of user one of value list of choices Opens a dialog with value displayed as the message and list of choices displayed as a popup menu for th
183. e control strip in the 3D View combines the ticks counter from the 2D view control strip and the controls from the right portion of the interface toolbar 74 Interface Guide NetLogo 4 0 User Manual a gt M view updates A KR ticks O Settings continuous 3 oo normal speed Here are the settings for the View accessible by editing the View or by pressing the Settings button in the Interface Toolbar Model Settings World Location of origin Center HA minimum x coordinate for patches max pxcor 10 maximum x coordinate for patches minimum y coordinate for patches max pycor 10 Torus 21x21 Y World wraps horizontally maximum y coordinate for patches Y World wraps vertically View Patch size 13 Font size 10 measured in pixels of labels on agents Y Turtle shapes ifunchecked turtles appear as squares Tick counter Y Show tick counter Tick counter label ticks Cancel Apply Cok Notice that the settings are broken up into three groups There are world view and ticks counter settings World settings affect the properties of the world that the turtles live in changing them may require resetting the world View and tick counter settings only affect the appearance changing them will not affect the outcome of the model The world settings allow you to define the boundaries and topology of the world At the top of the left side of the world panel you can ch
184. e given name a string Subsequent plotting commands will affect the current plot set current plot pen set current plot pen penname The current plot s current pen is set to the pen named penname a string If no such pen exists in the current plot a runtime error occurs set default shape NetLogo Dictionary 321 NetLogo 4 0 User Manual set default shape turtles string set default shape breed string ig Specifies a default initial shape for all turtles or for a particular breed When a turtle is created or it changes breeds it shape is set to the given shape This command doesn t affect existing turtles only turtles you create afterwards The specified breed must be either turtles or a breed defined by the breed keyword and the specified string must be the name of a currently defined shape In new models the default shape for all turtles is default Note that specifying a default shape does not prevent you from changing an individual turtle s shape later turtles don t have to be stuck with their breed s default shape create turtles 1 new turtle s shape is default create cats 1 77 new turtle s shape is default set default shape turtles circle create turtles 1 new turtle s shape is circle create cats 1 77 new turtle s shape is circle set default shape cats cat set default shape dogs dog create cats 1 7 new turtle s shape is cat ask cats set breed dogs all cats become dogs an
185. e hubnet broadcast example hubnet send example t broadcast A 3 14 et send Jimmy A 3 14 t broadcast STR1 et send 12 MIST MES TRI HERE I THERE t send t message source L2 t broadcast L2 t broadcasi t send susie 41 1 hubnet broadcast ubnet send teacher user names 3Jimmy user names Jimmy susie susie bob george bob george Examples Study the models in the HubNet Computer Activities and the HubNet Calculator Activities sections of the Models Library to see how these primitives are used in practice in the Procedures window Disease is a good one to start with 172 HubNet Authoring Guide NetLogo 4 0 User Manual Calculator HubNet Information For information on writing HubNet activities using calculator clients please_contact us Computer HubNet Information The following information is specific to Computer HubNet How To Make a Client Interface Open the HubNet Client Editor found in the Tools Menu Add any buttons sliders switches monitors plots choosers or notes that you want just as you would in the interface tab You ll notice that the information you enter for each of the widgets is slightly different than in the Interface panel Widgets on the client don t interact with the model in the same way Instead of a direct link to commands and reporters the widgets send messages back to the
186. e in NetLogo s Models Library in the Code Examples section It s called Tutorial 3 Notice that this listing is full of comments which begin with semicolons Comments let you mix an explanation the code right in with the code itself You might use comments to help others understand your model or you might use them as notes to yourself In the Procedures tab comments are gray so your eyes can pick them out easily turtles own energy for keeping track of when the turtle is ready 7 to reproduce and when it will die to setup clear all setup patches setup turtles do plots end to setup patches ask patches set pcolor green end 66 Tutorial 3 Procedures NetLogo 4 0 User Manual to setup turtles create turtles number uses the value of the number slider to create turtles ask turtles setxy random xcor random ycor end to go if ticks gt 500 stop 77 stop after 500 ticks move turtles eat grass reproduce check death regrow grass tick 77 increase the tick counter by 1 each time through do plots end to move turtles ask turtles right random 360 forward 1 set energy energy 1 when the turtle moves it looses one unit of energy end to sat grass ask turtles if pcolor green set pcolor black 7 the value of energy from grass slider is added to energy set energy energy energy from grass ifelse show energy set label energy the label is set t
187. e of the room is a tile labeled 0 0 meaning that if the room was divided in half one way and then the other way these two dividing lines would intersect on this tile We now have a coordinate system that will help us locate objects within the room How many tiles away is the 0 0 tile from the right side of the room How many tiles away is the 0 0 tile from the left side of the room In NetLogo the number of tiles from right to left is called world width And the number of tiles from top to bottom is world height These numbers are defined by top bottom left and right boundaries 34 Tutorial 1 Models NetLogo 4 0 User Manual world width max pxcor max pycor world height 0 0 min pycor In these diagrams max pxcor is 3 min pxcor is 3 max pycor is 2 and min pycor is 2 When you change the patch size the number of patches tiles doesn t change the patches only get larger or smaller on the screen Let s look at the effect of changing the minimum and maximum coordinates in the world e Using the Settings dialog that is still open change max pxcor to 30 and max pycor value to 10 Notice that min pxcor and min pycor change too That s because by default the origin 0 0 is in the center of the world What happened to the shape of the view e Press the setup button Now you can see the new patches you have created e Edit the view by pressing the Settings button again e Change the
188. e root is set to level INFO the appender is org nlogo api XMLFileAppender and layout is org nlogo api XMLLayout Together these generate a nicely formatted XML file as defined in the netlogo_logging dtd which is based on the log4j dtd If the appender is a FileAppender including the XMLFileAppender a new file is start each time the user opens a model lt xml version 1 0 encoding UTF 8 gt lt DOCTYPE log4j configuration SYSTEM log4j dtd gt lt log4j configuration debug false xmlns log4j http jakarta apache org log4j gt lt appender name A1 class org nlogo api XMLFileAppender gt lt layout class org nlogo api XMLLayout gt lt appender gt lt category name org nlogo api Logger WIDGETS gt lt priority value off gt lt category gt lt category name org nlogo api Logger TURTLES gt lt priority value off gt lt category gt lt category name org nlogo api Logger LINKS gt lt priority value off gt lt category gt lt root gt lt priority value info gt lt appender ref ref A1 gt lt root gt Logging 177 NetLogo 4 0 User Manual lt log4j configuration gt This configuration first defines an appender named A1 of type XMLFileAppender with an XMLLayout The appender defines where the logging data goes in this case the data goes into a file In fact if NetLogo is given a FileAppender it will automatically start a new file every time
189. e user to select from Reports the item in list of choices selected by the user value may be of any type but is typically a string if yes user one of Set up the model yes no setup user yes or no user yes or no value Reports true or false based on the user s response to value value may be of any type but is typically a string if user yes or no Set up the model setup V variance variance list Reports the sample variance of a list of numbers Ignores other types of items The sample variance is the sum of the squares of the deviations of the numbers from their mean divided by one less than the number of numbers in the list show variance 2 7 4 3 5 gt 3 7 NetLogo Dictionary 339 NetLogo 4 0 User Manual W wait wait number Wait the given number of seconds This needn t be an integer you can specify fractions of seconds Note that you can t expect complete precision the agent will never wait less than the given amount but might wait slightly more repeat 10 fd 1 wait 0 5 See also_every watch watch agent ig Puts a spotlight on agent In the 3D view the observer will also turn to face the subject See also follow subject reset perspective watch me watch me watch me Asks the observer to watch the calling agent See also watch while while reporter commands If reporter reports false exit the loop Otherwise run commands and r
190. e using the Command Center The Command Center The Command Center is located in the Interface Tab and allows you to enter commands or directions to the model Commands are instructions you can give to NetLogo s agents turtles patches links and the observer Refer to the Interface Guide for details explaining the different parts of the Command Center Tutorial 2 Commands 37 NetLogo 4 0 User Manual In Traffic Basic e Press the setup button e Locate the Command Center e Click the mouse in the white box at the bottom of the Command Center e Type the text shown here Command Center Clear observer gt ask patches set pcolor yellow J v e Press the return key What happened to the View You may have noticed the background of the View has turned all yellow and the street has disappeared Why didn t the cars turn yellow too Looking back at the command that was written we asked only the patches to change their color In this model the cars are represented by a different kind of agent called turtles Therefore the cars did not received these instructions and thus did not change What happened in the Command Center You may have noticed that the command you just typed is now displayed in the white box in the middle of the Command Center as shown below Command Center WA Clear observer gt ask patches set pcolor yellow observer gt v e Type in the white box at the bottom of th
191. e we will load the Forest Fire model and the path will be given using the typical Macintosh install location NLLoadModel Applications NetLogo 4 0 models Sample Models Earth Science Fire nlogo Executing a NetLogo command Commands can be executed by passing a string of commands to NLCommand The NLCommand function automatically splices common Mathematica data types into strings suitable for NetLogo The following commands set the density using a single string or set the density using a Mathematica defined variable myDensity NLCommand set density 50 myDensity 60 NLCommand set density myDensity Reporting information from NetLogo NetLogo data can be reported back to Mathematica using NLReport This includes numbers strings boolean values and lists Report count turtles Reporty lts Ox C O14 VCO sO mao 110 pareceres For more information see the NetLogo Mathematica Tutorial notebook included with NetLogo The notebook walks you through the process of using the link with many examples along the way If you do not have Mathematica but are considering using the link you can download a PDF of the evaluated tutorial Installation The NetLogo Mathematica link requires NetLogo 4 0 and Mathematica 6 0 or greater To install the NetLogo Mathematica link e Go to the menu bar in Mathematica e Click on File and select Install e In the Install Mathematica Item dialog 184 Mat
192. e x and y coordinates of the mouse location will appear Note that the mouse location might not correspond exactly to any actual data points in the plot If you need to know the exact coordinates of plotted points use the Export Plot menu item and inspect the resulting file in another program When you create a plot as with all widgets the edit dialog automatically appears 00 Plot Name pla ZO O y S X axis label X min 0 0 X max 10 0 Y axis label Y min 0 0 Y max 10 0 Mi Autoplot Plot Pens Choose Pen to Edit default H Rename Delete Create Color black A Mode Line HJ Interval 1 0 M Show in Legend Custom Color 3 Many of the fields are fairly self explanatory the name of the plot labels for the x and y axes and ranges for the axes If Autoplot is checked the x and y changes will automatically readjust as points are added to the plot if they are outside the current range In the plot pens section of the dialog you can create and customize different pens in this plot You must always have a least one pen in every plot You start out with one named default you probably want to rename it something that is meaningful in the model All the items in the box below the pen name are settings relevant to that particular pen e Set the color to one of the NetLogo base hues or a custom color using the color swatches e Mode allows you to change the appearance of the plot pen line bar
193. eading in information from a file data that is stored in the file flows into your model On the other hand writing allows data to flow out of your model and into a file When a NetLogo model runs as an applet within a web browser it will only be able to read data from files which are in the same directory on the server as the model file Applets cannot write to any files When working with files always begin by using the primitive ile open This specifies which file you will be interacting with None of the other primitives work unless you open a file first The next file primitive you use dictates which mode the file will be in until the file is closed reading or writing To switch modes close and then reopen the file The reading primitives include file read file read line file read characters and file at end Note that the file must exist already before you can open it for reading Code Examples File Input Example The primitives for writing are similar to the primitives that print things in the Command Center except that the output gets saved to a file They include file print file show file type and file write Note that you can never overwrite data In other words if you attempt to write to a file with existing data all new data will be appended to the end of the file If you want to overwrite a file use ile delete to delete it then open it for writing Code Examples File Output Example Programming Guid
194. eady exists in the table for the given key it is replaced table remove table remove table key Removes the mapping in table for key table to list table to list table Reports a list with the content of table The list will be a list of two element lists or pairs The first element in the pair is the key and the second element is the value 198 Array and Table Extensions Sound Extension The Sound Extension for NetLogo provides primitives to add sound to NetLogo models It supports two ways of making sound MIDI sounds and playback of pre recorded sound files Using the Sound Extension The sound extension comes preinstalled To use the extension in your model add a line to the top of your procedures tab extensions sound If your model already uses other extensions then it already has an extensions line in it so just add sound to the list For more information on using NetLogo extensions see the Extensions Guide For examples that use the sound extension see the Sound section under Code Examples in the NetLogo Models Library Note that the sound extension only works in the NetLogo application It doesn t work in saved applets MIDI support The MIDI part simulates a 128 key electronic keyboard with 47 drums and 128 melodic instruments as provided by_General MIDI Level 1 specification It supports 15 polyphonic instrument channels and a single percussion channel Using more than 15 different melodic instruments s
195. eate dogs 1 ask dogs show count cats here gt 5 turtles on lt breeds gt on turtles on agent turtles on agentset lt breeds gt on agent lt breeds gt on agentset Reports an agentset containing all the turtles that are on the given patch or patches or standing on the same patch as the given turtle or turtles ask turtles if not any turtles on patch ahead 1 fat ask turtles if not any turtles on neighbors die of loneliness If the name of a breed is substituted for turtles then only turtles of that breed are included turtles own lt breeds gt own turtles own var7 lt breeds gt own var The turtles own keyword like the globals breed lt breeds gt own and patches own keywords can only be used at the beginning of a program before any function definitions It defines the variables belonging to each turtle NetLogo Dictionary 335 NetLogo 4 0 User Manual If you specify a breed instead of turtles only turtles of that breed have the listed variables More than one breed may list the same variable breed cats cat breed dogs dog breed hamsters hamster turtles own eyes legs 7 applies to all breeds cats own fur kittens hamsters own fur cage dogs own hair puppies See also globals patches own breed lt breeds gt own type type value Prints value in the Command Center not followed by a carriage return unlike print and show T
196. eck death ask turtles if energy lt 0 die end tO regrow grass ask patches if random 100 lt 3 set pcolor green end Each of these procedures uses the if command Each turtle when it runs reproduce checks the value of the turile s energy variable If it is greater than 50 then the turtle runs the commands inside the first set of brackets In this case it decreases the turtle s energy by 50 then hatches a new turtle with an energy of 50 The hatch command is a NetLogo primitive which looks like this hatch number commands This turtle creates number new turtles each identical to its parent and asks the new turtle s that have been hatched to run commands You can use the commands to give the new turtles different colors headings or whatever In our case we run one command We set the energy for the newly hatched turtle to be 50 When each turtle runs check death it will check to see if its energy is less or equal to O If this is true then the turtle is told to die die is a NetLogo primitive When each patch runs regrow grass it will check to see if a random integer from 0 to 99 is less than 3 If so the patch color is set to green This will happen 3 of the time on average for each patch since there are three numbers 0 1 and 2 out of 100 possible that are less than 3 e Switch to the Interface tab now and press the setup and go buttons You should see some interesting behavior in your mo
197. edures menu e scrollable Interface tab Version 1 0 April 2002 e initial release after a series of betas What s New 15 16 NetLogo 4 0 User Manual What s New System Requirements NetLogo runs on almost any current computer If you have any trouble with NetLogo not working write bugs ccl northwestern edu System Requirements Application Windows NetLogo runs on Windows Vista XP 2000 NT ME and 98 The NetLogo installer for Windows installs Java version 1 5 0 for NetLogos exclusive use only Other programs on your computer are not affected Mac OS X Mac OS X 10 4 or newer is strongly recommended 10 3 and 10 2 are also supported Please run Software Update to ensure that you have the latest Java Other platforms NetLogo should work on any platform on which a Java Virtual Machine version 1 4 1 or later is installed Version 1 5 0_12 or later is preferred You should run NetLogo as follows java server Xmsl6M Xmx1024M Djava ext dirs jar NetLogo jar e The server option gives increased performance e The xm options allow NetLogo to use additional RAM e The Djava option ensures that the 3D view uses the version of JOGL bundled with NetLogo System Requirements Saved Applets NetLogo models saved as Java applets should work in any web browser where Java version 1 4 1 or later is installed System Requirements 3D View Occasionally an older less powerful system is not able to su
198. el steps Essentially you are making one experiment step equal 100 model steps I m varying a global variable declared in the Procedures tab but it doesn t work Why It s probably because your setup commands or setup procedure are using clear a11 causing the values set by BehaviorSpace to be cleared One possible workaround is to change your experiment s setup commands to preserve the value of the variable e g let old varl varl setup set varl old varl This works because even clear a11 doesn t clear the values of local variables made with let Another possible workaround is to change your model s setup procedure to use more specific clearing commands to clear only what you want cleared Why are some of my results cut off in Excel In some versions of Excel spreadsheets can t have more than 256 columns See_a Microsoft support article on the subject Possible workarounds include e Use a newer version of Excel such as Excel 2007 e Use a different program besides Excel e Ask BehaviorSpace to generate results in table format instead of or in addition to spreadsheet format Excel can read our table format too e Change your experiment so the result has fewer columns Extensions I m writing an extension Why does the compiler say it can t find org nlogo api You need to add NetLogo jar to your classpath when compiling NetLogo jar is included with NetLogo 234 FAQ Frequently Asked Questions NetLogo Di
199. eling Northwestern University Evanston IL The project gratefully acknowledges the support of the National Science Foundation REPP and ROLE Programs grant numbers REC 9814682 and REC 0126227 Third party licenses MersenneTwisterFast For random number generation NetLogo uses the MersenneTwisterFast class by Sean Luke The copyright for that code is as follows Copyright c 2003 by Sean Luke Portions copyright c 1993 by Michael Lecuyer All rights reserved Redistribution and use in source and binary forms with or without modification are permitted provided that the following conditions are met e Redistributions of source code must retain the above copyright notice this list of conditions and the following disclaimer e Redistributions in binary form must reproduce the above copyright notice this list of conditions and the following disclaimer in the documentation and or other materials provided with the distribution e Neither the name of the copyright owners their employers nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS AND ANY EXPRESS OR IMPLIED WARRANTIES INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED IN NO EVENT SHALL THE COPYRIGHT OWNERS OR Copyright Info
200. els Vector shapes are fully scalable and rotatable NetLogo caches bitmap images of vector shapes size 1 1 5 and 2 in order to speed up execution 108 Programming Guide NetLogo 4 0 User Manual A turtle s shape is stored in its shape variable and can be set using the set command New turtles have a shape of default The set default shape primitive is useful for changing the default turtle shape to a different shape or having a different default turtle shape for each breed of turtle The shapes primitive reports a list of currently available turtle shapes in the model This is useful if for example you want to assign a random shape to a turtle ask turtles set shape one of shapes Use the Turtle Shapes Editor to create your own turtle shapes or to add shapes to your model from our shapes library or to transfer shapes between models For more information see the Shapes Editor_section of this manual The thickness of the lines used to draw the vector shapes can be controlled by the set line thickness primitive Code Examples Breeds and Shapes Example Shape Animation Example Link Shapes Link Shapes are similar to turtle shapes only you use the Link Shape Editor to create and edit them Link shapes consist of between 0 and 3 lines which can have different patterns and a direction indicator that is composed of the same elements as turtle shapes Links also have a shape variable that can be set to any link shape that
201. emporary because they vanish when the plot is cleared by the clear plot clear all plots or clear all commands To create a temporary plot pen use the create temporary plot pen command Once the pen has been created you can use it like any ordinary pen By default the new pen is down is black in color has an interval of 1 and plots in line mode Commands are available to change all of these settings see the Plotting section of the NetLogo Dictionary Using a Legend You can show the legend of a plot by selecting the Show legend checkbox in the edit dialog If you don t want a particular pen to show up in the legend you can uncheck the Show in Legend checkbox for that pen also in the edit dialog Conclusion Not every aspect of NetLogo s plotting system has been explained here See the Plotting section of the NetLogo Dictionary for information on additional commands and reporters related to plotting Many of the Sample Models in the Models Library illustrate various advanced plotting techniques Also check out the following code examples Code Examples Plot Axis Example Plot Smoothing Example Rolling Plot Example Strings To input a constant string in NetLogo surround it with double quotes The empty string is written by putting nothing between the quotes like this Programming Guide 115 NetLogo 4 0 User Manual Most of the list primitives work on strings as well butfirst string gt tring butlast string
202. en down repeat num sides fd len rt 360 num sides end Elsewhere in the program you could ask turtles to each draw an octagon with a side length equal to its who number ask turtles draw polygon 8 who Reporter procedures Programming Guide 89 NetLogo 4 0 User Manual Just like you can define your own commands you can define your own reporters You must do two special things First use to report instead of to to begin your procedure Then in the body of the procedure use report to report the value you want to report to report absolute value number ifelse number gt 0 report number report number end Variables Variables are places to store values such as numbers A variable can be a global variable a turtle variable or a patch variable If a variable is a global variable there is only one value for the variable and every agent can access it But each turtle has its own value for every turtle variable and each patch has its own value for every patch variable Some variables are built into NetLogo For example all turtles have a color variable and all patches have a pcolor variable The patch variable begins with p so it doesn t get confused with the turtle variable If you set the variable the turtle or patch changes color See next section for details Other built in turtle variables including xcor ycor and heading Other built in patch variables include pxcor and
203. ent in the agentset in random order ert 4 show sort who of turtles gt 0 1 2 3 show sort who who of turtles gt 0 1 4 9 300 NetLogo Dictionary NetLogo 4 0 User Manual one of one of ageniset one of list From an agentset reports a random agent If the agentset is empty reports_ nobody From a list reports a random list item It is an error for the list to be empty ask one of patches set pcolor green 7 a random patch turns green ask patches with any turtles here show one of turtles here for each patch containing turtles prints one of those turtles 7 suppose mylist is 1 2 3 4 5 6 show one of mylist 7 prints a value randomly chosen from the list See also_n of or boolean1 or boolean2 Reports true if either boolean1 or boolean2 or both is true Note that if condition1 is true then condition2 will not be run since it can t affect the result if pxcor gt 0 or pycor gt 0 set pcolor red 7 patches turn red except in lower left quadrant other other agentset Reports an agentset which is the same as the input agentset but omits the calling agent show count turtles here gt 10 show count other turtles here gt 9 other end other end Mo If run by a turtle reports the turtle at the other end of the asking link NetLogo Dictionary 301 NetLogo 4 0 User Manual If run by a link reports the turtle at the end of the link t
204. ep Example to setup plot count turtles end to go plot count turtles end Note that in this example we plot from both the setup and go procedures That s because we want our plot to include the initial state of the system We plot at the end of the go procedure not the beginning because we want the plot always to be up to date after the go button stops If you need to specify both the x and y values of the point you want plotted then use plot xy instead Code Example Plotting Example Other kinds of plots By default NetLogo plot pens plot in line mode so that the points you plot are connected by a line Programming Guide 113 NetLogo 4 0 User Manual If you want to move the pen without plotting you can use the plot pen up command After this command is issued the plot and plot xy commands move the pen but do not actually draw anything Once the pen is where you want it use plot pen down to put the pen back down If you want to plot individual points instead of lines or you want to draw bars instead of lines or points you need to change the plot pen s mode Three modes are available line bar and point Line is the default mode Normally you change a pen s mode by editing the plot This changes the pen s default mode It s also possible to change the pen s mode temporarily using the set plot pen mode command That command takes a number as input 0 for line 1 for bar 2 for point Histograms A h
205. ep over time Let s take a look and see what would happen to the sheep if we change one of the settings e Turn the grass switch on e Press setup and go and let the model run for a similar amount of time as before What did this switch do to the model Was the outcome the same as your previous run Just like buttons switches have information attached to them Their information is set up in an on off format Switches turn on off a separate set of directions These directions are usually not necessary for the model to run but might add another dimension to the model Turning the grass switch on affected the outcome of the model Prior to this run the growth of the grass stayed constant This is not a realistic look at the predator prey relationship so by setting and turning on a grass growth rate we were able to model all three factors sheep wolf and grass populations Another type of setting is called a slider Sliders are a different type of setting then a switch A switch has two values on or off A slider has a range of numeric values that can be adjusted For example the initial number sheep slider has a minimum value of O and a maximum value of 250 The model could run with O sheep or it could run with 250 sheep or anywhere in between Try this out and see what happens As you move the marker from the minimum to the maximum value the number on the right side of the slider changes this is the number the slider
206. epeat The reporter may have different values for different agents so some agents may run commands a different number of times than other agents while any other turtles here fd 1 7 turtle moves until it finds a patch that has 7 no other turtles on it 340 NetLogo Dictionary NetLogo 4 0 User Manual who who This is a built in turtle variable It holds the turtle s who number or ID number an integer greater than or equal to zero You cannot set this variable a turile s who number never changes Who numbers start at O A dead turtle s number will not be reassigned to a new turtle until you use the_clear turtles or_clear all commands at which time who numbering starts over again at 0 Example show who of turtles with color red 7 prints a list of the who numbers of all red turtles in the Command Center in random order crt 100 ifelse who lt 50 set color red set color blue 7 turtles 0 through 49 are red turtles 50 through 99 are blue You can use the turtle reporter to retrieve a turtle with a given who number See also_turtle with agentset with reporter Takes two inputs on the left an agentset usually turtles or patches On the right a boolean reporter Reports a new agentset containing only those agents that reported true in other words the agents satisfying the given condition show count patches with pcolor red 7 prints the number of red patch
207. er of model runs will be x 1 y 1 x 1 y 2 x 1 y 3 x 2 y 1 and so on Repetitions Sometimes the behavior of a model can vary a lot from run to run even if the settings don t change if the model uses run numbers If you want to run the model more than once at each combination of settings enter a higher number here than one Measure runs using these reporters This is where you specify what data you want to collect from each run For example if you wanted to record how the population of turtles rose and fell during each run you would enter count tiles BehaviorSpace Guide 155 NetLogo 4 0 User Manual You can enter one reporter or several or none at all If you enter several each reporter must be on a line by itself for example Counte EROGS count mice Count soared s If you don t enter any reporters the runs will still take place This is useful if you want to record the results yourself your own way such as with the export wor1d command Measure runs at every step Normally NetLogo will measure model runs at every step using the reporters you entered in the previous box If you re doing very long model runs you might not want all that data Uncheck this box if you only want to measure each run after it ends Setup commands These commands will be used to begin each model run Typically you will enter the name of a procedure that sets up the model typically setup But it is also possible to include other commands
208. er you can also send values to any interface elements that display information monitors sliders switches choosers and input boxes note that plots and the view are special cases that have their own sections There are two primitives that allow you to send information hubnet send and hubnet broadcast Broadcast sends the information to all the clients and send sends to a specific or a selected group of the clients As suggested earlier nothing on the client updates automatically if a value changes on the server it is your responsibility as the model author to update monitors on the client and if you change a variable on the server associated with another interface element not as a response to a change message from that widget then you must also update the value on the client For example say you have a slider on the client called step size and a monitor called Step Size note that the names must be different you might write updating code like this if hubnet message tag step size ask student with user id hubnet message source set step size hubnet messag hubnet send user id Step Size step siz You can send any type of data you want numbers strings lists lists of lists lists of strings however if the data is not appropriate for the receiving interface element say if you were to send a string to a slider the message will be ignored Here are a few code examples for different types of data data typ
209. erpreted from their 2D shapes If a shape is a rotatable shape it is assumed to be a top view and it is extruded as if through a cookie cutter and oriented parallel to the xy plane as in Ants If a shape is non rotatable it is assumed to be a side view so it is drawn always facing the observer and with no thickness as in Wolf Sheep Predation Command Center The Command Center allows you to issue commands directly without adding them to the model s procedures Commands are instructions you give to the agents in your model This is useful for inspecting and manipulating agents on the fly Tutorial 2 Commands is an introduction to using commands in the Command Center 78 Interface Guide NetLogo 4 0 User Manual Let s take a look at the design of the Command Center Command Center WY Clear turtles gt set color red patches gt set pcolor white observer gt ask turtle 10 set color blue observer gt ask turtle 1 set color blue observer gt crt 10 The smaller box below the large box is where you type a command After typing it press the Return or Enter key to run it To the left of where you type is a popup menu that initially says observer gt You can choose either observer turtles or patches to specify which agents run the command you type Tip a quicker way to change between observer turtles and patches is to use the tab key on your keyboard Accessing previous commands
210. erval 1 0 M Show in Legend Next you will need to create two pens 62 e With the Plot dialog box still open press the Create button in the Plot dialog to create a new pen e Enter the name of this pen as turtles and press OK in the Enter Pen Name dialog see image below e Press the Create button in the Plot dialog again to create a second new pen e Enter the name of this pen as grass and press OK in the Enter Pen Name dialog see image below e Select the color for this pen and change it to green e Select OK in the Plot dialog box Tutorial 3 Procedures NetLogo 4 0 User Manual i AAA Plot Name Totals X axis label time Xmin 0 X max 10 Y axis label totals Ymin 0 Ymax 10 Y Autoplot gt Ss Plot Pens Choose Pen to Edit turtles Rename Delete Create Color black jeoo Enter Pen Name egend gt Custom Color t Enter a name for the pen 7 grass aK rass y OT oss JD _ eC PL Cancel OD Note that when you create the plot you can also set the minimum and maximum values on the X and Y axes You ll want to leave the Autoplot checkbox checked so that if anything you plot exceeds the minimum and maximum values for the axes the axes will automatically grow so you can see all the data e Setup and run the model again You can now watch the plot being drawn as the model is running Your plot should have the general sha
211. es lt breed gt with link with lt breed gt with turtle link with turtle Report the link between turtle and the caller If no link exists then it reports nobody ert 2 ask turtle 0 create link with turtle 1 show link with turtle 1 prints link 0 1 NetLogo Dictionary 341 NetLogo 4 0 User Manual with max agentset with max reporter Takes two inputs on the left an agentset usually turtles or patches On the right a reporter Reports a new agentset containing all agents reporting the maximum value of the given reporter show count patches with max pxcor 7 prints the number of patches on the right edge See also max one of with min agentset with min reporter Takes two inputs on the left an agentset usually turtles or patches On the right a reporter Reports a new agentset containing only those agents that have the minimum value of the given reporter show count patches with min pycor 7 prints the number of patches on the bottom edge See also min one of with local randomness with local randomness commands The commands are run without affecting subsequent random events This is useful for performing extra operations such as output without changing the outcome of a model Example Run 1 random seed 50 setup repeat 10 go 7 Run 2 random seed 50 setup with local randomness watch one of turtles repeat 10 go Since one of is used inside without loc
212. es kts daly gaia ec Aaa cts ante adorn SP a A aaa een 225 How do change how many patches there are eres 225 Can use the mouse to paint in the View occcccnonoocccnnnnnccononanonnncnnncncnnnnnonncnnnnnnnn 225 How big can my model be How many turtles patches procedures buttons and so on can My model Conta iia so votes adeeb sadia Pando dio damn idiota 226 ix NetLogo 4 0 User Manual Table of Contents FAQ Frequently Asked Questions Can import GIS data into NetLod Rasa 226 My model runs slowly How can Speed it up iene 227 Can have more than one model Open ata time 227 Can change the choices in a chooser on the fly 227 Can divide the code for my model up into several files 2 228 How do show the legend in a plot e eeeerrrreeeeaaaeaaareresaaana 228 POCKET GY 809 AS IR DE CURAR SERES EDER CORRE TE 228 How is the NetLogo language different from the StarLogo and StarLogoT languages How do convert my StarLogo or StarLogoT model to NetLogo 228 How does the NetLogo language differ from other Logos 2 nennen 228 How come my model from an earlier NetLogo doesn t work right 229 Why does my code have strange characters init e rieeenaana 229 Why do get a runtime error when use setxy random world width random world height It worked Defore ooccccccooonccccononcccnonanononnnnncccnnnnnnonncncnnnnnnnnnnnnnnnnnos 230
213. es when to update the view and how you can influence when it gets updated NetLogo offers two updates modes continuous updates and tick based updates You can switch between NetLogo s two view update modes using a popup menu at the top of the Interface tab Continuous updates are the default when you start up NetLogo or start a new model Nearly every model in our Models Library however uses tick based updates 110 Programming Guide NetLogo 4 0 User Manual Continuous updates are simplest but tick based updates give you more control over when and how often updates happen It s important exactly when an update happens because when updates happen determines what you see on the screen If an update comes at an unexpected time you may see something unexpected perhaps something confusing or misleading It s also important how often updates happen because updates take time The more time NetLogo spends updating the view the slower your model will run With fewer updates your model runs faster Continuous updates Continuous updates are very simple With continuous updates NetLogo updates the view a certain number of times per second by default 50 times a second when the speed slider is in the default middle setting If you move the speed slider to a slower setting NetLogo will update more than 50 times a second effectively slowing down the model On a faster setting NetLogo will update less than 50 times a sec
214. et energy energy As each turtle wanders it will lose one unit of energy at each step 54 Tutorial 3 Procedures NetLogo 4 0 User Manual e Switch to the Interface tab now and press the setup button and the go button You ll see the patches turn black as turtles travel over them Monitors Next you will create two monitors in the Interface tab with the Toolbar You make them just like buttons and sliders using the monitor icon on the Toolbar Let s make the first monitor now e Create a monitor using the monitor icon on the Toolbar and click on an open spot in the Interface A dialog box will appear e In the dialog box type count turtles see image below e Press the OK button to close the dialog box Tutorial 3 Procedures 55 NetLogo 4 0 User Manual Monitor Display name Decimal places 3 FontSize 11 full precision is 17 Cancel Cok 4 ZA turtles is an agentset the set of all turtles count tells us how many agents are in that set Let s make the second monitor now e Create a monitor using the monitor icon on the Toolbar and click on an open spot in the Interface A dialog box will appear e Inthe Reporter section of the dialog box type count patches with pcolor green see image below e In the Display name section of the dialog box type green patches e Press the OK button to close the dialog box 56 Tutorial 3 Procedures NetLo
215. et pcolor red 7 each turtle makes a red splotch around itself inspect inspect agent Opens an agent monitor for the given agent turtle or patch inspect patch 2 4 an agent monitor opens for that patch inspect one of sheep an agent monitor opens for a random turtle from 7 the sheep breed 278 NetLogo Dictionary NetLogo 4 0 User Manual int int number Reports the integer part of number any fractional part is discarded show int 4 7 gt 4 show int 3 5 gt 3 is agent is agentset is boolean is lt breed gt is directed link is link is link set is list is number is patch is patch set is string is turtle is turtle set is undirected link is agent value is agentset value is boolean value is lt breed gt value is directed link value is link value is link set value is list value is number value is patch value is patch set value is string value is turtle value is turtle set value is directed link value Reports true if value is of the given type false otherwise NetLogo Dictionary 279 NetLogo 4 0 User Manual item item index list item index string On lists reports the value of the item in the given list with the given index On strings reports the character in the given string at the given index Note that the indices begin from 0 not 1 The first item is item 0 the second item is item 1 and so on 7 suppose mylist is 2
216. evoke the decentralized interconnected nature of the phenomena you can model with NetLogo including network phenomena It also refers to HubNet the multiuser participatory simulation environment included in NetLogo How do cite NetLogo in an academic publication NetLogo itself Wilensky U 1999 NetLogo _http ccl northwestern edu netlogo Center for Connected Learning and Computer Based Modeling Northwestern University Evanston IL HubNet Wilensky U amp Stroup W 1999 HubNet http ccl northwestern edu netlogo hubnet html Center for Connected Learning and Computer Based Modeling Northwestern University Evanston IL How do cite a model from the Models Library in a publication The correct citation is included in the CREDITS AND REFERENCES section of every model s Information tab Where and when was NetLogo created NetLogo was first created in 1999 by Uri Wilensky at the Center for Connected Learning and Computer Based Modeling then at Tufts University in the Boston area NetLogo grew out of StarLogoT which was authored by Wilensky in 1997 In 2000 the CCL moved to Northwestern University in the Chicago area NetLogo 1 0 came out in 2002 2 0 in 2008 3 0 in 2005 and 4 0 in 2007 FAQ Frequently Asked Questions 217 NetLogo 4 0 User Manual What programming language was NetLogo written in NetLogo is written entirely in Java version 1 4 1 What s the difference between StarLogo MacStarLogo StarLo
217. fewer than that many characters left it will report all of the remaining characters Note that it will return every character including newlines and spaces Also note that the file open command must be called before this reporter can be used and there must be data remaining in the file Use the reporter filg at end to determine if you are at the end of the file file open my file txt print file read characters 5 Current line in file is Hello World gt Hello See also file open file read line file read line Reads the next line in the file and reports it as a string It determines the end of the file by a carriage return an end of file character or both in a row It does not return the line terminator characters Also note that the file open command must be called before this reporter can be used and there must be data remaining in the file Use the reporter filge at end to determine if you are at the end of the file file open my file txt print file read line gt Hello World See also file open file show file show value Prints value to an opened file preceded by the calling agent and followed by a carriage return The calling agent is included to help you keep track of what agents are producing which lines of output 264 NetLogo Dictionary NetLogo 4 0 User Manual Also all strings have their quotes included similar to_file write Note that this command is the file i o equivalent of show an
218. ffom gogo output port reverse because thisway and thatway will always be the same direction provided the connector s polarity is the same gogo talk to output ports gogo talk to output ports output portlist This command will set the corresponding output ports as active They will be the ones affected by the commands such as gogo output port on and gogo output port off The user can talk to one or multiple ports at the same time Output ports are typically connected to motors but you could also use bulbs LEDs and relays Output ports are identified by one letter names a b c and q Examples 7 talk to all output ports gogo talk to output ports a b er nar 7 will give power to all output ports gogo output port on 7 talk to output ports A and D gogo talk to output ports a a 7 will turn off output ports A and D The other output ports will keep their current state gogo output port off gogo talk to output ports Tat b 5 turn off remaining output ports gogo output port off gogo ping 208 GoGo Extension NetLogo 4 0 User Manual gogo ping Checks the status of GoGo board This is mostly used to make sure the board is connected to the correct serial port It reports true if the GoGo Board responds to a diagnostic message and false otherwise Example print gogo ping gogo sensor gogo sensor sensor Reports the value of the sensor named sensor as a number Sensors are named by n
219. fic Basic found in the Social Science section e Run the model for a couple minutes to get a feel for it e Consult the Information tab for any questions you may have about this model In this model you will notice one red car in a stream of blue cars The stream of cars are all moving in the same direction Every so often they pile up and stop moving This is modeling how traffic jams can form without any cause such as an accident a broken bridge or an overturned truck No centralized cause is needed for a traffic jam to form You may alter the settings and observe a few runs to get a full understanding of the model As you are using the Traffic Basic model have you noticed any additions you would like to make to the model Looking at the Traffic Basic model you may notice the environment is fairly simple a black background with a white street and number of blue cars and one red car Changes that could be made to the model include changing the color and shape of the cars adding a house or street light creating a stop light or even creating another lane of traffic Some of these suggested changes are cosmetic and would enhance the look of the model while the others are more behavioral We will be focusing more on the simpler or cosmetic changes throughout most of this tutorial Tutorial 3 will go into greater detail about behavioral changes which require changing the Procedures tab To make these simple changes we will b
220. flag to tell Java to optimize performance for server type applications we recommend this flag for best performance in most situations Note the use of Xmx to specify a maximum heap size of one gigabyte If you don t specify a maximum heap size you will get your VM s default size which may be unusably small One gigabyte is an arbitrary size which should be more than large enough for most models you can specify a different limit if you want Note also that xms is used to specify a larger than default initial heap size This helps some models run faster by making garbage collection more efficient The mode1 argument is used to specify the model file you want to open The experiment argument is used to specify the name of the experiment you want to run At the time you create an experiment setup in the GUI you assign ita name Here s another example that shows some additional optional arguments java server Xmsl16M Xmx1024M cp NetLogo jar org nlogo headless HeadlessWorkspace model Fire nlogo N xperiment experiment2 max pxcor 100 min pxcor 100 max pycor 100 N min pycor 100 no results 158 BehaviorSpace Guide NetLogo 4 0 User Manual Note the use of the optional max pxcor max pycor etc arguments to specify a different world size than that saved in the model It s also possible for the experiment setup to specify values for the world dimensions if they are specified by the experime
221. g color color and pcolor What is the difference between color and pcolor e Choose turtles from the popup menu in the Command Center or use the tab key e Type set color blue and press return What happened to the cars Think about what you did to make the cars turn blue and try to make the patches turn red If you try to ask the patches to set color red an error message occurs Command Center Ts turtles gt set color yellow ERROR You can t use COLOR in a patch context because COLOR is turtle only patches gt set color red ig 40 Tutorial 2 Commands NetLogo 4 0 User Manual e Type set pcolor red instead and press return We call color and pcolor variables Some commands and variables are specific to turtles and some are specific to patches For example the color variable is a turtle variable while the pcolor variable is a patch variable Go ahead and practice altering the colors of the turtles and patches using the set command and these two variables To be able to make more changes to the colors of turtles and patches or shall we say cars and backgrounds we need to gain a little insight into how NetLogo deals with colors In NetLogo all colors have a numeric value In all of the exercises we have been using the name of the color This is because NetLogo recognizes 16 different color names This does not mean that NetLogo only recognizes 16 colors There are many shades in between these col
222. gentset e is directed or undirected as declared by the keyword Most often the agentset is used in conjunction with ask to give commands to only the links of a particular breed directed link breed streets street directed link breed highways highway to setup clear all ert 2 Create a link from turtle 0 to turtle 1 ask turtle 0 create street to turtle 1 Create a link from turtle 1 to turtle 0 ask turtle 0 create highway from turtle 1 end ask turtle O show one of in links 7 prints street 0 1 ask turtle O show one of out links 7 prints highway 1 0 See also breed undirected link breed 254 NetLogo Dictionary NetLogo 4 0 User Manual display display Causes the view to be updated immediately Exception if the user is using the speed slider to fast forward the model then the update may be skipped Also undoes the effect of the no display command so that if view updates were suspended by that command they will resume no display ask turtles jump 10 set color blue set size 5 display 7 turtles move change color and grow with none of their intermediate states visible to the user only their final state Even if no display was not used display can still be useful because ordinarily NetLogo is free to skip some view updates so that fewer total updates take place so that models run faster This command lets you force a view update so whatever changes have t
223. gentsets are equal using or e Use member to see whether a particular agent is a member of an agentset This only scratches the surface See the Models Library for many more examples and consult the NetLogo Dictionary for more information about all of the agentset primitives More examples of using agentsets are provided in the individual entries for these primitives in the NetLogo Dictionary In developing familiarity with programming in NetLogo it is important to begin to think of compound commands in terms of how each element passes information to the next one Agentsets are an important part of this conceptual scheme and provide the NetLogo developer with a lot of power and flexibility as well as being more similar to natural language Code Example Ask Ordering Example Earlier we said that agentsets are always in random order a different random order every time If you need your agents to do something in a fixed order you need to make a list of the agents instead See the Lists section below Breeds NetLogo allows you to define different breeds of turtles and breeds of links Once you have defined breeds you can go on and make the different breeds behave differently For example you could have breeds called sheep and wolves and have the wolves try to eat the sheep or you could have link breeds called streets and sidewalks where foot traffic is routed on sidewalks and car traffic is routed on streets You define turtle b
224. ggers are found in org nlogo api Logger When referring to the loggers in the configuration file you should use the fully qualified name So for example the logger GLOBALS would actually be org nlogo api Logger GLOBALS Level Example lt event logger org nlogo api Logger GLOBALS timestamp 1177341065988 a global variable _ info e INES type globals gt changes debug lt name gt FOO lt name gt lt value gt 51 0 lt value gt lt event gt lt event logger org nlogo api Logger GRE timestamp 1177341065988 level INFO a type slider gt sliders switches lt action gt changed lt action gt choosers input lt name gt foo lt name gt boxes are info lt value gt 51 0 lt value gt changed through RS i lt min gt 0 0 lt min gt the interface CARR da lt inc gt 1 0 lt inc gt lt parameters gt lt event gt lt event logger org nlogo api Logger CODE code is compiled timestamp 1177341072208 including level INFO command center f Be Conan CENTERS info lt action gt compiled lt action gt procedures tab Bada eave Mew cones slider bounds and lt agentType gt 0 lt agentType gt buttons lt errorMessage gt success lt errorMessage gt lt event gt lt event logger org nlogo api Logger WIDGETS timestamp 1177341058351 a widget is added level INFO or removed from info type slider gt the interface lt name gt lt name gt lt
225. go 4 0 ask is serial that is the agents run the commands inside the ask one at a time The following information describes the behavior of the ask concurrent command which behaves the way the old ask behaved ask concurrent produces simulated concurrency via a mechanism of turn taking The first agent takes a turn then the second agent takes a turn and so on until every agent in the asked agentset has had a turn Then we go back to the first agent This continues until all of the agents have finished running all of the commands An agent s turn ends when it performs an action that affects the state of the world such as moving or creating a turtle or changing the value of a global turtle patch or link variable Setting a local variable doesn t count The forward fd and back bk commands are treated specially When used inside ask concurrent these commands can take multiple turns to execute During its turn the turile can only move by one step Thus for example fd 20 is equivalent to repeat 20 fd 1 where the turtle s turn ends after each run of fd If the distance specified isn t an integer the last fraction of step takes a full turn So for example fd 20 3 is equivalent to repeat 20 fd 1 Ed Dos The jump command always takes exactly one turn regardless of distance To understand the difference between ask and ask concurrent consider the following two commands ask turtles fd 5 ask concurrent turtles fd
226. go 4 0 User Manual ROS ticks 0 e0e Monitor Reporter kount patches with pcolor green count turtles green patches 50 1225 Display name green patches Decimal places 3 full precision is 17 Font Size 11 Cancel Cok Here we re using count again to see how many agents are in an agentset patches is the set of all the patches but we don t just want to know how many patches there are total we want to know how many of them are green That s what with does it makes a smaller agentset of just those agents for whom the condition in the brackets is true The condition is pcolor green so that gives us just the green patches Now we have two monitors that will report how many turtles and green patches we have to help us track what s going on in our model As the model runs the numbers in the monitors will automatically change e Use the setup and go buttons and watch the numbers in the monitors change Switches and labels The turtles aren t just turning the patches black they re also gaining and losing energy As the model runs try using a turtle monitor to watch one turtle s energy go up and down It would be nicer if we could see every turtle s energy all the time We will now do exactly that and add a switch so we can turn the extra visual information on and off e To create a switch click on the switch icon on the Toolbar in the Interface tab and click on an open spot i
227. goT and NetLogo The original StarLogo was developed at the MIT Media Lab in 1989 1990 and ran on a massively parallel supercomputer called the Connection Machine A few years later 1994 a simulated parallel version was developed for the Macintosh computer That version eventually became MacStarLogo StarLogoT 1997 developed at the Center for Connected Learning and Computer Based Modeling CCL is essentially an extended version of MacStarLogo with many additional features and capabilities Since then two multi platform Java based multi agent Logos have been developed NetLogo from the CCL and a Java based version of StarLogo from MIT The NetLogo language and environment differ in many respects from MIT StarLogo s Both languages were inspired by the original StarLogo but were redesigned in different ways NetLogo s design was driven by the need to revise and expand the language so it is easier to use and more powerful and by the need to support the HubNet architecture NetLogo incorporates almost all of the extended functionality of our earlier StarLogoT as well as a great many newer features What license is NetLogo released under Are there are any legal restrictions on use redistribution etc The license is given in the Copyright section of the NetLogo User Manual as well as in the application s about box and the README file accompanying the download A quick summary of the license is that use is unrestricted including
228. h min instead show min one of turtles xcor ycor 7 reports the first turtle with the smallest sum of 7 coordinates See also_with min min pxcor min pycor min pxcor min pycor These reporters give the minimum x coordinate and minimum y coordinate respectively for patches which determines the size of the world Unlike in older versions of NetLogo the origin does not have to be at the center of the world However the minimum x and y coordinates must be less than or equal to zero Note You can set the size of the world only by editing the view these are reporters which cannot be set crt 100 setxy random float min pxcor random float min pycor 7 distributes 100 turtles randomly in the 5 third quadrant See also max pxcor max pycor world width and_world height mod number1 mod number2 Reports number modulo number2 that is the residue of number mod number2 mod is is equivalent to the following NetLogo code NetLogo Dictionary 291 NetLogo 4 0 User Manual numberl floor numberl number2 number2 Note that mod is infix that is it comes between its two inputs show 62 mod 5 gt 2 show 8 mod 3 gt 1 See also_remainder mod and remainder behave the same for positive numbers but differently for negative numbers modes modes list Reports a list of the most common item or items in list The input list may contain any NetLogo values If the input is an empty list
229. h turtles on patch and BREED on patch instead comparison operators now work on turtles patches and links new primitive reporter plot pen exists old rgb and hsb primitives renamed to approximate rgb and approximate hsb they now expect inputs in 0 255 range instead of 0 1 0 the hsb and rgb reporters now report RGB lists instead of NetLogo colors new primitive import pcolors rgb imports images into the patches as RGB colors new reporter net logo applet lets you test whether the model is running as an applet or not code may now set a slider to values which violate the minimum maximum or increment 4 locals no longer exists use let instead extension primitives must now by default be referred to using the extension name e g sound drums instead of just drums the file read primitive now skips over comments got rid of many undocumented alternate names for primitives e user interface changes note is the new name for the widget formerly known as text box sliders may now be moved using the mouse scroll wheel built in variables are now syntax colored the same purple as primitive reporters dialogs associated with the user primitives have more consistent appearance and functionality contextual menus added to text areas for cut copy paste and dictionary lookup Pens button removed from plots you now edit the plot to show or hide the pens legend e engine fixes monitors now use an auxiliary random generator so code i
230. h agent type right alongside observer turtles patches The primitives involving links are no longer considered experimental they are now fully part of the language Models that use the old experimental turtle based link primitives will need to be updated to use link agents The differences are not huge but hand updating is required Links are documented in the Links section of the Programming Guide and in the NetLogo Dictionary entries for the link primitives See the Networks section of the Models Library for example models that use links There are also some link based Code Examples First you will need to remove any breeds called links if you are only using one type of links then you will not have to use breeds at all If you are using multiple types of links see undirected link breeds and directed 1ink breeds Commands and reporters that contain the word links like __create 1inks with etc will automatically be converted to the new form without underscores create links with However primitives that use a different breed name such as edges will not be converted You will need to remove the underscores by hand and unless you are declaring a link breed with that name you will need to change the breed designation to links The commands remove 1ink s with from to no longer exist Instead you should ask the links in question to die For example ask turtle 0 __remove links with link neighbors becomes
231. h is 5 farthest right in the world max one of max one of agentset reporter Reports the agent in the agentset that has the highest value for the given reporter If there is a tie this command reports one random agent with the highest value If you want all such agents use with max instead show max one of patches count turtles here 7 prints the first patch with the most turtles on it See also with max max pxcor max pycor max pxcor max pycor These reporters give the maximum x coordinate and maximum y coordinate respectively for patches which determines the size of the world Unlike in older versions of NetLogo the origin does not have to be at the center of the world However the maximum x and y coordinates must be greater than or equal to zero Note You can set the size of the world only by editing the view these are reporters which cannot be set crt 100 setxy random float max pxcor random float max pycor 7 distributes 100 turtles randomly in the 5 first quadrant See also_min pxcor min pycor world width and_world height NetLogo Dictionary 289 NetLogo 4 0 User Manual mean mean list Reports the statistical mean of the numeric items in the given list Ignores non numeric items The mean is the average i e the sum of the items divided by the total number of items show mean xcor of turtles 7 prints the average of all the turtles x coordinates median median list
232. h is the zero force length or the natural length of the springs This is the length which all springs try to achieve either by pushing out their nodes or pulling them in repulsion constant is a measure of repulsion between the nodes It is the force that 2 nodes at a distance of 1 unit will exert on each other The repulsion effect tries to get the nodes as far as possible from each other in order to avoid crowding and the spring effect tries to keep them at about a certain distance from the nodes they are connected to The result is the laying out of the whole network in a way which highlights relationships among the nodes and at the same time is crowded less and is visually pleasing The layout algorithm is based on the Fruchterman Reingold layout algorithm More information about this algorithm can be obtained_here to make a triangle set default shape turtles circle CEE 3 ask turtle 0 create links with other turtles ask turtle 1 create link with turtle 2 repeat 30 layout spring turtles links 0 2 5 1 lays the nodes in a triangle end layout tutte layout tutte turtle set link set radius The turtles that are connected by links in link set but not included in turile set are placed in a circle layout with the given radius There should be at least 3 agents in this agentset The turtles in turtle set are then laid out in the following manner Each turtle is placed at centroid or barycenter of the po
233. h student controls a traffic light in a simulated city The class as a whole tries to make traffic flow efficiently through the city As the simulation runs data is collected which can afterwards be analyzed on a computer or calculator For more information on participatory simulations and their learning potential please visit the Participatory Simulations Project web site Understanding HubNet NetLogo NetLogo is a programmable modeling environment It comes with a large library of existing simulations both participatory and traditional that you can use and modify Content areas include social science and economics biology and medicine physics and chemistry and mathematics and computer science You and your students can also use it to build your own simulations For more about NetLogo see the NetLogo Users Manual In traditional NetLogo simulations the simulation runs according to rules that the simulation author specifies HubNet adds a new dimension to NetLogo by letting simulations run not just according to rules but by direct human participation Since HubNet builds upon NetLogo we recommend that before trying HubNet for the first time you become familiar with the basics of NetLogo To get started using NetLogo models see_Tutorial 1 Running Models in the NetLogo Users Manual HubNet Architecture HubNet simulations are based on a client server architecture The activity leader uses the NetLogo application to run a HubNet act
234. hat isn t the asking turtle These definitions are difficult to understand in the abstract but the following examples should help ask turtle 0 create link with turtle 1 ask turtle O ask link 0 1 show other end ask turtle 1 ask link 0 1 show other end ask link 0 1 ask turtle 0 show other end 117 115 115 prints turtle 1 prints turtle 0 prints turtle 1 As these examples hopefully make plain the other end is the end that is neither asking nor being asked out lt breed gt neighbor out link neighbor out lt breed gt neighbor turtle out link neighbor turtle Reports true if there is a directed link going from the caller to turtle ert 2 ask turtle 0 create link to turtle 1 show in link neighbor turtle 1 prints show out link neighbor turtle 1 prints ask turtle 1 show in link neighbor turtle 0 prints show out link neighbor turtle 0 prints false true true false out lt breed gt neighbors out link neighbors out lt breed gt neighbors out link neighbors Reports the agentset of all the turtles that have directed links from the caller crt 4 ask turtle 0 create links to other turtles ask out link neighbors set color pink ask turtle 1 ask out link neighbors set color orange end turtles 1 3 turn pink no turtles change colors since turtle 1 only has in links rr rr 302 NetLogo Dictionary NetLogo 4 0 User Manual
235. he lack of a carriage return allows you to print several values on the same line The calling agent is not printed before the value unlike_show type 3 type print 4 gt 3 4 See also_print show and_write See also output type U undirected link breed undirected link breed lt link breeds gt lt link breed gt This keyword like the globals and breeds keywords can only be used at the beginning of the Procedures tab before any procedure definitions It defines an undirected link breed Links of a particular breed are always either all directed or all undirected The first input defines the name of the agentset associated with the link breed The second input defines the name of a single member of the breed Any link of the given link breed e is part of the agentset named by the link breed name e has its built in variable breed set to that agentset e is directed or undirected as declared by the keyword Most often the agentset is used in conjunction with ask to give commands to only the links of a particular breed undirected link breed streets street 336 NetLogo Dictionary NetLogo 4 0 User Manual undirected link breed highways highway to setup clear all ert 2 ask turtle 0 create street with turtle 1 ask turtle 0 create highway with turtle 1 end ask turtle 0 show sort my links 7 prints street 0 1 highway 0 1 See also breed directed link breed untie u
236. he default shapes too Aotat 1 ott EKA IMSS DO 411250 f pS y tia ua y os Ey EM im TA de amp E a 0 9 Ge 148 Shapes Editor Guide NetLogo 4 0 User Manual By default there is only one Link shape in a model that is default This shape is simply a single straight line with a simple arrowhead if the link happens to be directed Creating and Editing Turtle Shapes Pressing the New button will make a new shape Or you may select an existing shape and press Edit Tools In the upper left corner of the editing window is a group of drawing tools The arrow is the selection tool which selects an already drawn element To draw a new element use one of the other seven tools e The line tool draws line segments e The circle square and polygon tools come in two versions solid and outline When using the polygon tool click the mouse to add a new segment to the polygon When you re done adding segments double click After you draw a new element it is selected so you can move delete or reshape it if you want e To move it drag it with the mouse e To delete it press the Delete button e To reshape it drag the small handles that appear on the element only when it is selected e To change its color click on the new color Shapes Editor Guide 149 NetLogo 4 0 User Manual Previews As you draw your shape you will also see it in five smaller sizes in the five preview areas found near
237. he edges of the world is shorter face will use the wrapped path If the caller and the agent are at the exact same position the caller s heading won t change facexy 260 NetLogo Dictionary NetLogo 4 0 User Manual facexy number number Set the caller s heading towards the point x y If wrapping is allowed by the topology and the wrapped distance around the edges of the world is shorter and wrapping is allowed facexy will use the wrapped path If the caller is on the point x y the caller s heading won t change file at end file at end Reports true when there are no more characters left to read in from the current file that was opened previously with file open Otherwise reports false file open my file txt print file at end gt false Can still read in more characters print file read line gt This is the last line in file print file at end gt true We reached th nd of the file See also file open file close all file close file close Closes a file that has been opened previously with file open Note that this and file close all are the only ways to restart to the beginning of an opened file or to switch between file modes If no file is open does nothing See also file close all file open file close all file close all Closes all files if any that have been opened previously with file open See also file close file open NetLogo Dictionary 261 NetLogo 4 0 User
238. heap size of 16 megabytes and a maximum heap size of one gigabyte This is enough for most models Here s how to specify the heap sizes on the command line java server Dsun java2d noddraw true Xmsl6M Xmx1024M Note that we recommend the server flag for best performance in most situations On Windows we also recommend setting the noddraw option to true when using the GUI as Direct Draw can conflict with OpenGL Example with GUI Here is a small but complete program that starts the full NetLogo application opens a model moves a slider sets the random seed runs the model for 50 ticks and then prints a result import org nlogo app App import java awt EventQueue public class Examplel public static void main String argv App main argv try EventQueue invokeAndWait new Runnable public void run Controlling Guide 179 NetLogo 4 0 User Manual try App app open models Sample Models Earth Science Fire nlogo catch java io IOException ex ex printStackTrace 13 App app command set density 62 APp app command random seed 0 App app command setup App app command repeat 50 go System out println App app report burned trees catch Exception ex ex printStackTrace In order to compile and run this Net Logo jar from the NetLogo distribution must be in the classpath In addition the 1ib directory al
239. heep her 1f prey nobody ask prey die link link end1 end2 lt breed gt end1 end2 Given the who numbers of the endpoints reports the link connecting the turtles If there is no such link reports nobody To refer to breeded links you must use the singular breed form with the endpoints ask link 0 1 set color green NetLogo Dictionary 285 NetLogo 4 0 User Manual 77 unbreeded link connecting turtle 0 and turtle 1 will turn green ask directed link 0 1 set color red 7 directed link connecting turtle 0 and turtle 1 will turn red See also_patch at link heading link heading Reports the heading in degrees at least 0 less than 360 from end1 to end2 of the link ask link 0 1 print link heading 7 prints towards other end of endl of link 0 1 See also link length link length link length Reports the distance between the endpoints of the link ask link 0 1 print link length 7 prints distance other end of endl of link 0 1 See also link heading link set link set value link set value value Reports an agentset containing all of the links anywhere in any of the inputs The inputs may be individual links link agentsets nobody or lists or nested lists containing any of the above link set self link set my links of nodes with color red See also turtle set patch set links links Reports the agentset consisting of all links show count li
240. hematica Link NetLogo 4 0 User Manual e Select Package for Type of item to install e Click Source and select From file e In the file browser go to the location of your NetLogo installation e click on the Mathematica Link subfolder and select NetLogo m e For Install Name enter NetLogo You can either install the NetLogo link in your user base directory or in the system wide directory If the NetLogo link is installed in the user base directory other users on the system must also go through the NetLogo Mathematica link installation process to use it This option might be preferable if you do not have permission to modify files outside of your home directory Otherwise you can install NetLogo Mathematica link in the system wide Mathematica base directory Known Issues e A NetLogo session cannot be quit without exiting J Link the Java Mathematica link entirely This may disrupt other packages that make use of J Link This problem will be resolved in a future version e If a model loaded with the NetLogo Mathematica link uses a NetLogo extension the extension must be located in the same directory as the extension itself If the extension is located in NetLogo s application wide extensions directory it will not be found This problem will be resolved in a future version e Calls to NetLogo such as NLCommand and NLReport cannot be aborted Credits The primary developer of the NetLogo Mathematica link was Eyta
241. hes with pcolor green end Note that we use the plot command to add the next point to a plot However before doing that we need to tell NetLogo two things First we need to specify what plot we will be using since later our model might have more than one plot and second we need to specify which pen we want to plot with we will be using two pens on this plot The plot command moves the current plot pen to the point that has an X coordinate equal to 1 greater than the previously plotted X coordinate and a Y coordinate equal to the value given in the plot command in the first case the number of turtles and in the second case the number of green patches As the pens move they each draw a line In order for set current plot Totals to work you ll have to add a plot to your model in the Interface tab then edit it so its name is the same name used in the procedures Even one extra space in the name will throw it off it must be exactly the same in both places e Create a plot using the plot icon on the Toolbar and click on an open spot in the Interface Tutorial 3 Procedures 61 NetLogo 4 0 User Manual e Set its Name to Totals see image below e Set the X axis label to time e Set the Y axis label to total e ANO Name Totals X axis label time Xmin 0 Xmax 10 Y axis label totals Ymin 0 Y max 10 M Autoplot Plot Pens Choose Pen to Edit default BS Color black HA Mode Line Int
242. his issue convert the image file to an RGB palette Other bugs e Out of memory conditions are not handled gracefully e the Snap to Grid feature is disabled when zoomed in or out e Drawing and then erasing a line in the drawing may not erase every pixel exactly e Extensions that require additional external jars don t work from models saved as applets we are already working on fixing this e The 3D View doesn t work on some graphics configurations on others the 3D View works but 3D full screen mode doesn t e When running a model headless from the command line if the model was created in an earlier NetLogo version it may not work properly Use the GUI to open and resave the model in the current NetLogo version before running it headless Windows only bugs e The User Manual item on the Help menu does not work on every machine Windows 98 and ME are most likely to be affected newer Windows versions less so e On some laptops the Procedures and Info tabs may become garbled when you scroll them To avoid this bug reduce the size of the NetLogo window and or reduce the color depth of your monitor e g change from 32 bit to 16 or 8 bit color This is a bug in Java itself not in NetLogo per se For technical details on the bug see http developer java sun com developer bugParade bugs 4763448 html free registration required NetLogo users are encouraged to visit that site and vote for Sun to fix this bug Known Issues 19 Ne
243. horing Guide for details hubnet send view hubnet send view string hubnet send view list of strings For Calculator HubNet does nothing For Computer HubNet it acts as follows For a string this sends the current state of the 2D view in the NetLogo model to the Computer HubNet Client with string for its user name For a list of strings this sends the current state of the view in the NetLogo model to all the Computer HubNet Clients that have a user name that is in the list of strings Sending the 2D view to a nonexistent client using hubnet send view generates a hubnet exit message Note This is an experimental primitive and its behavior may change in a future version See the HubNet Authoring Guide for details hubnet set client interface NetLogo Dictionary 273 NetLogo 4 0 User Manual hubnet set client interface client type client info If client type is COMPUTER client info is an empty list for computer HubNet hubnet set client interface COMPUTER Future versions of HubNet will support other client types Even for Computer HubNet the meaning of the second input to this command may change See the HubNet Authoring Guide for details if if condition commands Reporter must report a boolean true or false value If condition reports true runs commands The reporter may report a different value for different agents so some agents may run commands and others don t if xcor gt O se
244. hout modification are permitted provided that the following conditions are met Redistribution of source code must retain the above copyright notice this list of conditions and the following disclaimer Redistribution in binary form must reproduce the above copyright notice this list of conditions and the following disclaimer in the documentation and or other materials provided with the distribution Neither the name of Sun Microsystems Inc or the names of contributors may be used to endorse or promote products derived from this software without specific prior written permission This software is provided AS IS without a warranty of any kind ALL EXPRESS OR IMPLIED CONDITIONS REPRESENTATIONS AND WARRANTIES INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE OR NON INFRINGEMENT ARE HEREBY EXCLUDED SUN MICROSYSTEMS INC SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES INNO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE PROFIT OR DATA OR FOR DIRECT INDIRECT SPECIAL CONSEQUENTIAL INCIDENTAL OR PUNITIVE DAMAGES HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES You acknowledge that this software is not designed or intended for use in
245. how they are typically used e print is useful in most situations e show lets you see which agent is printing what e type lets you print several things on the same line e write lets you print values in a format which can be read back in using file read 116 Programming Guide NetLogo 4 0 User Manual A NetLogo model may optionally have an output area in its Interface tab separate from the Command Center To send output there instead of the Command Center use the_output print output show output type and output write commands The output area can be cleared with the clear output command and saved to a file with export output The contents of the output area will be saved by the export world command The import world command will clear the output area and set its contents to the value in imported world file It should be noted that large amounts of data being sent to the output area can increase the size of your exported worlds If you use output print output show output type output write clear output or export output in a model which does not have a separate output area then the commands apply to the output portion of the Command Center File I O In NetLogo there is a set of primitives that give you the power to interact with outside files They all begin with the prefix file There are two main modes when dealing with files reading and writing The difference is the direction of the flow of data When you are r
246. ht e Now try checking and unchecking the view updates checkbox What happens Fast forwarding the model and turning off view updates are useful if you re impatient and want a model to run faster Fast forwarding moving the speed slider to the right drops view updates so the model can run fast since updating the view takes time that could be used for updating the view When view updates are off completely The model continues to run in the background and plots and monitors still update but if you want to see what s happening you need to turn view updates back 32 Tutorial 1 Models NetLogo 4 0 User Manual on by rechecking the box Most models run much faster when view updates are off The size of the view is determined by five separate settings Min and Max X Min and Max Y and Patch Size Let s take a look at what happens when we change the size of the view in the Wolf Sheep Predation model There are more world and view settings than there s room for in the toolbar The Settings button lets you get to the rest of the settings e Press the Settings button in the toolbar A dialog box will open containing all the settings for the view 8000 Model Settings World Location of origin Center HH minimum x coordinate for patches p max pxcor 25 maximum x coordinate for patches minimum y coordinate for patches max pycor 25 Torus 51 x 51 maximum y coordinate for patches Y World wraps horizo
247. iables A local variable is defined and used only in the context of a particular procedure or part of a procedure To create a local variable use the Let command You can use this command anywhere If you use it at the top of a procedure the variable will exist throughout the procedure If you use it inside a set of square brackets for example inside an ask then it will exist only inside those brackets to swap colors turtlel turtle2 let temp color of turtlel ask turtlel set color color of turtle2 ask turtle2 set color temp end NetLogo represents colors in two different ways First as numbers in the range 0 to 140 with the exception of 140 itself Below is a chart showing the range of colors you can use in NetLogo black 0 white 9 9 gray 5 8 9 9 9 red 15 18 19 19 9 orange 25 28 29 299 brown 35 BD 39 399 yellow 45 48 49 499 green 55 58 59 599 lime 65 68 69 699 turquoise 75 78 79 799 cyan 85 88 89 89 9 sky 95 98 99 99 9 blue 105 108 109 109 9 violet 115 118 119 1199 magenta 125 128 129 129 9 pink 135 137 138 139 139 9 Programming Guide 91 NetLogo 4 0 User Manual The chart shows that e Some of the colors have names You can use these names in your code e Every named color except black and white has a number ending in 5 e On either side of each named color are darker and lighter shades of the color e 0 is pure black 9 9 is pure white e 10 20 and so on are a
248. ial value nobody Useful in conjunction with the_user input primitive for converting the user s input into usable form show read from string 3 read from string 5 gt 8 show length read from string 1 2 3 gt 3 crt read from string user input Make how many turtles 7 the number of turtles input by the user are created reduce reduce reporter list Reduces a list from left to right using reporter resulting in a single value This means for example that reduce 1 22 1 2 3 4 is equivalent to 1 2 3 4 If list has a single item that item is reported It is an error to reduce an empty list In reporter use 1 and 2 to refer to the two objects being combined Since it can be difficult to develop an intuition about what reduce does here are some simple examples which while not useful in themselves may give you a better understanding of this primitive show reduce 1 2 1 2 3 gt 6 NetLogo Dictionary 313 NetLogo 4 0 User Manual show reduce 1 2 1 2 3 gt 4 show reduce 2 1 1 2 3 gt 2 show reduce 1 1 2 3 gt 1 show reduce 2 1 2 3 gt 3 how reduc sentence 1 2 1 2 3 4 5 dto 3 TA 5 how reduce fput 2 1 feut 1 1 2 340519 gt 5 43 2 1 u u Here are some more useful examples 7 find the longest string in a list to report longest string strings report reduce ifelse valu length
249. iano 67 Tenor Sax 4 Honky tonk Piano 68 Baritone Sax 5 Electric Piano 1 69 Oboe 6 Electric Piano 2 70 English Horn 7 Harpsichord 71 Bassoon 8 Clavi 72 Clarinet 202 Sound Extension Chromatic Percussion 9 Celesta 10 Glockenspiel 11 usic Box 12 Vibraphone 13 Marimba 14 Xylophone 15 Tubular Bells L6 Dulcimer Organ 17 Drawbar Organ 18 Percussive Organ 9 Rock Organ 20 Church Organ 21 Reed Organ 22 Accordion 23 Harmonica 24 Tango Accordion Guitar 25 Nylon String Guitar 26 Steel Acoustic Guitar 27 Jazz Electric Guitar 28 Clean Electric Guitar 29 Muted Electric Guitar 30 Overdriven Guitar 31 Distortion Guitar 32 Guitar harmonics Bass 33 Acoustic Bass 34 Fingered Electric Bass 35 Picked Electric Bass 36 Fretless Bass 37 Slap Bass 1 38 Slap Bass 2 39 Synth Bass 1 40 Synth Bass 2 Strings 41 Violin 42 Viola 43 Cello 44 Contrabass 45 Tremolo Strings 47 Pizzicato Strings 47 Orchestral Harp 48 Timpani Ensemble 49 String Ensemble 1 50 String Ensemble 2 51 Synth Strings 1 52 Synth Strings 2 53 Choir Aahs 54 Voice Oohs 55 Synth Voice 56 Orchestra Hit Brass 57 Trumpet Sound Extension NetLogo 4 0 User Manual Pipe 73 Piccolo 74 Flute 75 Recorder 76 Pan Flute 77 Blown Bottle 78 Shakuhachi 79 Whistle 80 Ocarina Synth Lead 81 Square Wave 82 Sawtooth Wave 83 Calliope
250. ients experimental Debug q Reset Local The HubNet Control Center lets you interact with the HubNet server It displays the name activity address and port number of your server The Mirror 2D View on clients checkbox controls whether the HubNet participants can see the view on their clients assuming there is a view in the client setup The Mirror plots on clients checkbox controls whether participants will receive plot information The client list on the right displays the names of clients that are currently connected to you activity To remove a participant from the activity select their name in the list and press the Kick button To launch your own HubNet client press the Local button this is particularly useful when you are debugging an activity The Reset button kicks out all currently logged in clients and reloads the client interface The lower part of the Control Center displays messages when a participant joins or leaves the activity To broadcast a message to all the participants click on the field at the bottom type your message and press Broadcast Message Troubleshooting started a HubNet activity but when participants open a HubNet Client my activity isn t listed On some networks the HubNet Client cannot automatically detect a HubNet server Tell your participants to manually enter the server address and port of your HubNet server which appear in the HubNet Control Center HubNet Guide 165
251. iew without advancing the tick counter examples Party Dice Stalagmite network models with animated layout models with mouse interaction buttons use the display command to force additional view updates so the user can see what is going on Speed slider Previous versions of NetLogo had a speed slider that could be used to make models run slower so you can see what s going on In NetLogo 4 0 the slider can be used to speed up models as well It does this by updating the view less frequently Updating the view takes time so the fewer updates the faster the model runs The default position of the slider is in the center When you re at the center the slider says normal speed As you move the slider away from the center position the model will gradually run faster or slower At very high speeds view updates become very infrequent and may be separated by several seconds It may feel like the model is actually running slower since the updates are so infrequent But watch the tick counter or other indicators such as plots and you ll see that yes the model really is running faster If the infrequent updates are disconcerting don t push the slider so far over When using tick based updates slowing the model down does not cause additional view updates Rather NetLogo simply pauses after each tick When using continuous updates slowing the model down means view updates become more closely spaced If you push the speed slider mo
252. ifferent behavior in the system being modeled So how are you to know which particular configuration of values or types of configurations will yield the kind of behavior you are interested in This amounts to the question of where in its huge multi dimension parameter space does your model perform best For example suppose you want speedy synchronization from the agents in the Fireflies model The model has four sliders number cycle length flash length and number flashes that have approximately 2000 100 10 and 3 possible values respectively That means there are 2000 100 10 3 600 000 possible combinations of slider values Trying combinations one at a time is hardly an efficient way to learn which one will evoke the speediest synchronization BehaviorSpace offers you a much better way to solve this problem If you specify a subset of values from the ranges of each slider it will run the model with each possible combination of those values and during each model run record the results In doing so it samples the model s parameter space not exhaustively but enough so that you will be able to see relationships form between different sliders and the behavior of the system After all the runs are over a dataset is generated which you can open in a different tool such as a spreadsheet database or scientific visualization application and explore By enabling you to explore the entire space of behaviors a model can
253. ill look for extensions in several places 1 In the folder of the current model 2 The extensions folder in the same location as the NetLogo application Each NetLogo extension consists of a folder with the same name as the extension entirely in lower case This folder must contain a JAR file with the same name as the folder For example the sound extension is stored in a folder called sound with a file inside called sound jar For more information about the contents of an extension s folder please see the section of this manual on Writing Extensions To install a NetLogo extension for use by any model put the extension s folder in the extensions directory in the NetLogo directory Or you can just keep the extension s folder in the same folder as the model that uses it Some extensions depend on additional files These files will be in the extension s folder along with the JAR file The folder may also contain other files such as documentation and example models Extensions Guide 187 NetLogo 4 0 User Manual Applets Models saved as applets using Save as Applet on NetLogo s File menu can make use of extensions The extension must be placed in the same directory holding the model file However applets still cannot use extensions that require additional external jars We plan on fixing this ina later release Writing Extensions We assume you have experience programming in Java Summary A NetLogo extension consists of a folde
254. ill need changes If your old model isn t working this section of the User Manual may be able to help you What issues you need to be aware of depends on how old your model is The older the NetLogo version it was made with the more issues you may need to be aware of This section does not list every change that was made for NetLogo 4 0 It discusses only the changes that are most likely to be issues for users For a complete list of changes see the What s New section e Since NetLogo 3 1 e Since NetLogo 3 0 Since NetLogo 3 1 Who numbering Prior to NetLogo 4 0 a dead turtle s who number stored in the who turtle variable could be reassigned to a later newborn turtle In NetLogo 4 0 who numbers are never reused until who numbering is reset to O by the clear al1 or clear turtles command This change in behavior may break a few old models Turtle creation randomized vs ordered NetLogo 4 0 provides two different observer commands for creating turtles create turtles crt and create ordered turtles cro crt gives the new turtles random colors and random integer headings cro assigns colors sequentially and gives the turtles sequential equally spaced headings with the first turtle facing north heading of 0 Prior to NetLogo 4 0 the crt command behaved the way cro does now If your old model depends on the ordered behavior you will need to change your code to use cro instead of crt It is common for old models that
255. ime error when use setxy random world width random world height It worked before e How do take the negative of a number e My turtle moved forward 1 but it s still on the same patch Why e How do keep my turtles on patch centers e patch ahead 1 is reporting the same patch my turtle is already standing on Why e How do give my turtles vision e Can agents sense what s in the drawing layer e I m getting numbers like 0 10000000004 and 0 799999999999 instead of 0 1 and 0 8 Why e The documentation says that random float 1 0 might return 0 0 but will never return 1 0 What if want 1 0 to be included e How can use different patch neighborhoods circular Von Neumann Moore etc e How can keep two turtles from occupying the same patch e How can find out if a turtle is dead e Does NetLogo have arrays 216 FAQ Frequently Asked Questions NetLogo 4 0 User Manual e Does NetLogo have hash tables or associative arrays e How can convert an agentset to a list or vice versa e How do stop foreach BehaviorSpace e How do gather data every n ticks e I m varying a global variable declared in the Procedures tab but it doesn t work Why e Why are some of my results cut off in Excel Extensions e I m writing an extension Why does the compiler say it can t find org nlogo api General Why is it called NetLogo The Logo part is because NetLogo is a dialect of the Logo language Net is meant to
256. imultaneously in a model will cause some sounds to be lost or cut off The pitch of a melodic instrument is specified by a key number The keys on the keyboard are numbered consecutively from 0 to 127 where 0 is the left most key Middle C is key number 60 The loudness of an instrument is specified by a velocity which represents the force with which the keyboard key is depressed Velocity ranges from 0 to 127 where 64 is the standard velocity A higher velocity results in a louder sound Primitives sound drums Sound Extension 199 NetLogo 4 0 User Manual sound drums Reports a list of the names of the 47 drums for use with sound play drum sound instruments sound instruments Reports a list of the names of the 128 instruments for use with sound play note sound play note later sound start note and sound stop note sound play drum sound play drum drum velocity Plays a drum sound play drum ACOUSTIC SNARE 64 sound play note sound play note instrument keynumber velocity duration Plays a note for a specified duration in seconds The agent does not wait for the note to finish before continuing to next command 7 play a trumpet at middle C for two seconds sound play note TRUMPET 60 64 2 sound play note later sound play note later delay instrument keynumber velocity duration Waits for the specified delay before playing the note for a specified duration in seconds The agent does
257. included in the turtle agentset are treated as anchors If there are no turtles with fixed positions the entire network will probably collapse on itself spring constantis a measure of the tautness of the spring See layout spring spring length is the zero force length or the natural length of the springs See layout spring repulsion constant is a measure of repulsion between the nodes See layout spring magnetic field strength is the force of the magnetic field Reasonable values range from 0 to 1 but 0 05 is a good default magnetic field type is a number in the range from 0 to 10 Choices are listed in the table below ers CSCS SOUTHEAST 4 ove CAN sommes met o TAN SSCS CONCENTRIC 10 Magnetic field runs clockwise around the origin in concentric circles If bidirectional is true then links try to align with the magnetic field by pushing attached turtles both in the direction of the field and in the opposite direction Otherwise the links just push in a single direction to make a tree set default shape turtles circle 282 NetLogo Dictionary Crt cd ask turtle 0 create lin create lin k with turtle k with turtle NetLogo 4 0 User Manual ask turtle 1 create link with turtle 3 create link with turtle 4 layout with a fairly strong SOUTH magnetic field repeat 50 __layout magspring turtles with who 0 links 0 3 4 1 50 5 false end layout radial
258. information Experimenting with commands We suggest you start experimenting with other turtle commands Type commands into the Command Center like turtles gt set color red or add commands to setup go Of move turtles Note that when you enter commands in the Command Center you must choose turtles gt patches gt Or observer gt in the popup menu on the left depending on which agents are going to Tutorial 3 Procedures 51 NetLogo 4 0 User Manual run the commands It s just like using ask turtles Or ask patches but saves typing You can also use the tab key to switch agent types which you might find more convenient than using the menu You might try typing turt les gt pen down into the Command Center and then pressing the go button Also inside the move turtles procedure you can try changing right random 360 to right random 45 Play around It s easy and the results are immediate and visible one of NetLogo s many strengths When you feel you ve done enough experimenting for now you re ready to continue improving the model you are building Patches and variables Now we ve got 100 turtles aimlessly moving around completely unaware of anything else around them Let s make things a little more interesting by giving these turtles a nice background against which to move e Go back to the setup procedure We can rewrite it as follows to setup clear all setup patches setup turtles end e The new defini
259. ing the topology reports false otherwise It is equivalent to patch ahead distance nobody carefully carefully commands1 commands2 Runs commands If a runtime error occurs inside commands1 NetLogo won t stop and alert the user that an error occurred It will suppress the error and run commands2 instead 246 NetLogo Dictionary NetLogo 4 0 User Manual The error message reporter can be used in commands2 to find out what error was suppressed in commands 1 See error message Note both sets of commands run without interruption as with the without interruption command carefully show 1 1 print error message gt 1 carefully show 1 0 print error message gt division by zero ceiling ceiling number Reports the smallest integer greater than or equal to number show ceiling 4 5 gt 5 show ceiling 4 5 gt 4 clear all ca clear all 5 Resets all global variables to zero and calls reset ticks clear turiles clear patches clear drawing clear all plots and clear output clear all plots clear all plots ig Clears every plot in the model See clear plot for more information clear drawing cd clear drawing a Clears all lines and stamps drawn by turtles clear links NetLogo Dictionary 247 NetLogo 4 0 User Manual clear links w Kills all links See also_die clear output clear output gt Clears all text from the model s output area if it ha
260. inished the experiment is complete Advanced usage BehaviorSpace Guide 157 NetLogo 4 0 User Manual Running from the command line It is possible to run BehaviorSpace experiments headless that is from the command line without any graphical user interface GUI This is useful for automating runs on a single machine or a cluster of machines No Java programming is required Experiment setups can be created in the GUI and then run later from the command line or if you prefer you can create or edit experiment setups directly using XML It is easiest if you create your experiment setup ahead of time in the GUI so it is saved as part of the model To run an experiment setup saved in a model here is an example command line java server Xmsl16M Xmx1024M cp NetLogo jar org nlogo headless HeadlessWorkspace model Fire nlogo N xperiment experiment 1 For this to work Net Logo jar must be present along with the 1ib subdirectory containing necessary libraries Both Net Logo jar and 1ib are included with NetLogo After the named experiment has run the results are sent to standard output in spreadsheet format as CSV To change this see below When running the HeadlessWorkspace class as an application it forces the system property java awt headless to be true This tells Java to run in headless mode allowing NetLogo to run on machines when a graphical display is not available Note the user ofthe server
261. instructions once The forever button executes the instructions over and over until you click on the button again to stop the action If you have assigned an action key to the button pressing the corresponding keyboard key will act just like a button press when the button is in focus Buttons with action keys have a letter in the upper right corner of the button to show what the action key is If the input cursor is in another interface element such as the Command Center pressing the action key won t trigger the button The letter in the upper right hand corner of the button will be dimmed in this situation To enable action keys click in the white background of the Interface tab SEE Slider Sliders are global variables which are accessible by all agents They are used in models as a quick way to change a variable without having to recode the procedure every time Instead the user moves the slider to a value and observes what happens in the model 78 Switch Switches are a visual representation for a true false variable The user is asked to set the variable to either on true or off false by flipping the switch a Chooser Choosers let the user choose a value for a global variable from a list of choices presented in a drop down menu 2 Input Input Boxes are global variables that contain strings or numbers The model author chooses what types of values the user can enter Input boxes can be set to check the syntax of a string for commands
262. ioned the wrap color primitive The scale color primitive is useful for converting numeric data into colors shade of will tell you if two colors are shades of the same basic hue For example shade of orange 27 is true because 27 is a lighter shade of orange Code Example Scale color Example demonstrates the scale color reporter RGB Colors The second color representation in NetLogo is an RGB red green blue list When using RGB colors the full range of colors is available to you RGB lists are made up of three integers between 0 and 255 if a number is outside that range 255 is repeatedly subtracted until it is in the range You can set any color variables in NetLogo color for turtles and links and pcolor for patches to an RGB list and that agent will be rendered appropriately So you can set the color of patch 0 0 to pure 92 Programming Guide NetLogo 4 0 User Manual red using the following code set pcolor 255 0 0 You can convert between RGB HSB hue saturation brightness and NetLogo colors using approximate hsb and approximate rgb from RGB HSB to NetLogo colors and extract hsb and extract rgb in the opposite direction You can use rgb to generate rgb lists and hsb to convert from an HSB color to RGB Since many colors are missing from the NetLogo color space approximate hsb and approximate rgb often can t give you the exact color you ask for but they try to come as close as possible Code Example The HSB and
263. is in the model By default links have the default shape though you can change that using set default shape The link shapes reporter reports all the link shapes included in the current model The thickness of the lines in the link shape is controlled by the thickness link variable Tick Counter In many NetLogo models time passes in discrete steps called ticks NetLogo includes a built in tick counter so you can keep track of how many ticks have passed The current value of the tick counter is shown above the view You can use the Settings button to hide the tick counter or change the word ticks to something else In code to retrieve the current value of the tick counter use the ticks reporter The tick command advances the tick counter by 1 The clear a11 command resets the tick counter to O If you want to reset the counter to O without clearing everything use the reset ticks command If your model is set to use tick based updates then the ti ck command will usually also update the view See the next section View Updates Programming Guide 109 NetLogo 4 0 User Manual When to tick We suggest using the tick command after your agents have completed all their movements and actions but before you plot or calculate statistics That way if the plotting or calculating code refers to the tick counter it will get the new value reflecting that the tick is now complete Example to go ask turtles move ask patches grow
264. istogram is a special kind of plot that measures how frequently certain values or values in certain ranges occur in a collection of numbers that arise in your model For example suppose the turtles in your model have an age variable You could create a histogram of the distribution of ages among your turtles with the histogram command like this histogram age of turtles The numbers you want to histogram don t have to come from an agentset they could be any list of numbers Note that using the histogram command doesn t automatically switch the current plot pen to bar mode If you want bars you have to set the plot pen to bar mode yourself As we said before you can change a pen s default mode by editing the plot in the Interface tab The width of the bars in a histogram is controlled by the plot pen s interval You can set a plot pen s default interval by editing the plot in the Interface tab You can also change the interval temporarily with the set plot pen interval command or the set histogram num bars If you use the latter command NetLogo will set the interval appropriately so as to fit the specified number of bars within the plot s current x range Code Example Histogram Example Clearing and resetting You can clear the current plot with the clear plot command or clear every plot in your model with clear all plots The clear a11 command also clears all plots in addition to clearing everything else in your model
265. ith lots of buttons switches sliders and monitors These interface elements allow you to interact with the model Buttons are blue they set up start and stop the model Sliders and switches are green they alter model settings Monitors and plots are beige they display data If you d like to make the window larger so that everything is easier to see you can use the zoom menu at the top of the window When you first open the model you will notice that the view is empty all black To begin the model you will first need to set it up Tutorial 1 Models 27 NetLogo 4 0 User Manual e Press the setup button What do you see appear in the view e Press the go button to start the simulation As the model is running what is happening to the wolf and sheep populations e Press the go button to stop the model Controlling the Model Buttons When a button is pressed the model responds with an action A button can be a once button or a forever button You can tell the difference between these two types of buttons by a symbol on the face of the button Forever buttons have two arrows in the bottom right corners like this Once buttons don t have the arrows like this Once buttons do one action and then stop When the action is finished the button pops back up Forever buttons do an action over and over again When you want the action to stop press the button again It will finish the current action then pop back
266. iven direction then in that direction x or y the world is bounded Patches along that boundary will have fewer than 8 neighbors and turtles will not move beyond the edge of the world See the Topology section for more information Procedures In NetLogo commands and reporters tell agents what to do A command is an action for an agent to carry out A reporter computes a result and report it Most commands begin with verbs create die jump inspect clear while most reporters are nouns or noun phrases Commands and reporters built into NetLogo are called primitives The NetLogo Dictionary has a complete list of built in commands and reporters Commands and reporters you define yourself are called procedures Each procedure has a name preceded by the keyword to The keyword end marks the end of the commands in the procedure Once you define a procedure you can use it elsewhere in your program Many commands and reporters take inputs values that the command or reporter uses in carrying out its actions Examples Here are two command procedures to setup clear all 7 clear the world ere 10 make 10 new turtles 88 Programming Guide NetLogo 4 0 User Manual end to go ask turtles fd 1 7 all turtles move forward one step rt random 10 Fi and turn a random amount lt random 10 end Note the use of semicolons to add comments to the program Comments make your program easier to read and understand In
267. ivity When NetLogo is running a HubNet activity we refer to it as a HubNet server Participants use a client application to log in and interact with the HubNet server There are two types of HubNet available With Computer HubNet participants run the HubNet Client application on computers connected by a regular computer network In_Calculator HubNet created in conjunction with Texas Instruments participants use Texas Instruments graphing calculators as clients which communicate via the Tl Navigator system We hope to add support for other types of clients such as cell phones and PDA s Personal Digital Assistants HubNet Guide 163 NetLogo 4 0 User Manual Computer HubNet Activities The following activities are available in the Models Library in the Computer HubNet Activities folder For many models you will find a discussion of its educational goals and suggested ways to incorporate it into your classroom in the Participatory Simulations Guide on the Participatory Simulations Project web site More information can also be found in the Information Tab in each model e Disease A disease spreads through the simulated population of students e Gridlock Students use traffic lights to control the flow of traffic through a city e Polling Ask students questions and plot their answers e Tragedy of the Commons Students work as farmers sharing a common resource Requirements To use Computer HubNet you need a netwo
268. k Note While the commands are running no other agents are allowed to run any code as with the without interruption command This ensures that if ask concurrent is being used the new turtles cannot interact with any other agents until they are fully initialized See also create turtles hatch sqrt sqrt number Reports the square root of number NetLogo Dictionary 327 NetLogo 4 0 User Manual stamp stamp The calling turtle or link leaves an image of its shape in the drawing at its current location Note The shapes made by stamp may not be pixel for pixel identical from computer to computer stamp erase stamp erase The calling turtle or link removes any pixels below it in the drawing inside the bounds of its shape Note The shapes made by stamp erase may not be pixel for pixel identical from computer to computer standard deviation standard deviation list Reports the unbiased statistical standard deviation of a list of numbers Ignores other types of items show standard deviation 1 2 3 4 5 6 gt 1 8708286933869707 show standard deviation energy of turtles 7 prints the standard deviation of the variable energy 7 from all the turtles startup startup rc User defined procedure which if it exists will be called when a model is first loaded to startup setup end stop stop The calling agent exits immediately from the enclosing procedure ask or ask like construct crt hatch sp
269. k ete ccisadw deta viet a A A gols asas taipa NEE 315 A 315 CA ee 316 O umi as 316 fESEl PErSPECIIVE Pira a da Alastor 316 A Sie cr hee te quad seats dete fada E na ait Metis Deer ta als as cates Sete Siar ER Den o he 316 FeSCi IIMeR sic os acc cts ca as a DE AA a dads Sid a o ents GUS aus din ds o ge E ea a Td 317 xvi NetLogo 4 0 User Manual Table of Contents NetLogo Dictionary FEVERS Cesc co ete E SGA Des coun DE adido od od 317 A 317 A SI a DAS O GOA RARA OO o 317 O 317 Md iaa 318 LOURO EAE IEN PEENE eee oe Sen EA ak ee a SO Seah meal mee oe Sa Ghat E Re cae de had de a 318 PU to ea io eno Mee ae en a ae ROD ese eee a es and 318 runtesull NSN EE dee RR ee 319 A 319 Scale Coli on tol dell 319 SO A A RA dr ad O o ad AA a 320 O O 320 ALEAR E E AA A A A 320 SS A O RN 320 set current directory cette eee e eee e eee eeeeeeeeeeeeeeeeeeeeeeneeeeeegeeegeeeeeeseeeeeeeeseeeeeeees 321 SETZCUITEN lO di 321 SCL CUrreNnt PlOT DEIN ii AAA tad 321 A A RI 321 set histogram num bars cece cece cece nn nr 322 set lihe thickness isis peace pido 322 set plot pen ColOr sims ssa dessas A AeA ade 323 set plot pen interval sasuiniaiaes atas id nla A TDI cabra da irado 323 set plot pen mode nr rre 323 set plot x range Set plot y ranQe ccooccccccccccccccnnonononanonnnc narrar 323 SOMA A A id 323 SAO ne 324 A A AR O E E RD a PS EAD ets E a 324 SNADES ui A A alada Da Seda 325
270. ked lists This is a technical term from computer science that means that when NetLogo needs to find an item in a list it must start at the beginning of the list and go from item to item until it finds the one it wants For example to find the 100th item NetLogo must step through the previous 99 items one at a time It also means that certain operations are especially efficient namely operations at the front of the list The first butfirst and fput reporters are all very fast they take the same amount of time to run no matter how long the list is So if you re building up a list by adding items to it one at a time it s much faster to use fput than 1put If that causes your list to end up backwards from how you wanted it you can always use reverse to reverse the list once you re done building it The length reporter is also fast NetLogo always keeps track of how long every list is so it never needs to actually measure Examples of reporters which are slower on longer lists include item lput butlast last and one of Math All numbers in NetLogo are stored internally as double precision floating point numbers as defined in the IEEE 754 standard They are 64 bit numbers consisting of one sign bit an 11 bit exponent and a 52 bit mantissa See the IEEE 754 standard for details An integer in NetLogo is simply a number that happens to have no fractional part No distinction is made between 3 and 3 0 they are the same number
271. l NetLogo worlds before NetLogo 3 1 A torus wraps in both directions meaning that the top and bottom edges of the world are connected and the left and right edges are connected So if a turtle moves beyond the right edge of the world it appears again on the left and the same for the top and bottom A box does not wrap in either direction The world is bounded so turtles that try to move off the edge of the world cannot Note that the patches around edge of the world have fewer than eight neighbors the corners have three and the rest have five Horizontal and vertical cylinders wrap in one direction but not the other A horizontal cylinder wraps vertically so the top of the world is connected to the bottom but the left and right edges are bounded A vertical cylinder is the opposite it wraps horizontally so the left and right edges are connected but the top and bottom edges are bounded Code Example Neighbors Example Since NetLogo 3 0 there have been settings to enable wrapping visually so if a turtle shape extends past an edge part of the shape will appear on the other edge of the view Turtles themselves are points that take up no space so they cannot be on both sides of the world at once but in the view they appear to take up space because they have a shape Programming Guide 121 NetLogo 4 0 User Manual Wrapping also affects how the view looks when you are following a turtle On a torus wherever the turtle goes you will al
272. l of aircraft air traffic aircraft navigation or aircraft communications or in the design construction operation or maintenance of any nuclear facility Licensee represents and warrants that it will not use or redistribute the Software for such purposes ASM For Java bytecode generation NetLogo uses the ASM library It is distributed under the following license Copyright c 2000 2005 INRIA France Telecom All rights reserved Redistribution and use in source and binary forms with or without modification are permitted provided that the following conditions are met 1 Redistributions of source code must retain the above copyright notice this list of conditions and the following disclaimer 2 Redistributions in binary form must reproduce the above copyright notice this list of conditions and the following disclaimer in the documentation and or other materials provided with the distribution 3 Neither the name of the copyright holders nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission Copyright Information 7 NetLogo 4 0 User Manual THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS AND ANY EXPRESS OR IMPLIED WARRANTIES INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE L
273. le Syntax This section contains technical terminology which will be unfamiliar to many readers Keywords The only keywords in the language are globals breed turtles own patches own to to report and end Built in primitive names may not be shadowed or redefined so they are effectively keywords as well Identifiers All primitives global and agent variable names and procedure names share a single global case insensitive namespace local names 1et variables and the names of procedure inputs may not shadow global names or each other Identifiers may contain letters digits and the following ASCII characters 2 1 lt gt 44 85 _0 8 Non ASCII characters are not currently allowed in identifiers We realize this is troublesome for international users and plan to address the issue in a future release Some primitive names begin with two underscores to indicate that they are experimental and are especially likely to change or be removed in future NetLogo releases Identifiers beginning with a question mark are reserved Scope NetLogo is lexically scoped Local variables including inputs to procedures are accessible within the block of commands in which they are declared but not accessible by procedures called by those commands 130 Programming Guide NetLogo 4 0 User Manual Comments The semicolon character introduces a comment which lasts until the end of the line There is no multi line comment syntax
274. lement void perform 2 Write a ClassManager Each extension must include in addition to any number of command and reporter classes a class that implements the interface org nlogo api ClassManager The ClassManager tells NetLogo which primitives are part of this extension In simple cases extend the abstract class org nlogo api DefaultClassManager which provides empty implementations of the methods from ClassManager that you aren t likely to need Here s the class manager for our example extension src SampleExtension java import org nlogo api public class SampleExtension extends DefaultClassManager public void load PrimitiveManager primitiveManager primitiveManager addPrimitive first n integers new IntegerList addPrimitive tells NetLogo that our reporter exists and what its name is 190 Extensions Guide NetLogo 4 0 User Manual 3 Write a Manifest The extension must also include a manifest The manifest is a text file which tells NetLogo the name of the extension and the location of the ClassManager The manifest must contain three tags e Extension Name the name of the extension e Class Manager the fully qualified name of a class implementing org nlogo api ClassManager e Net Logo Extension API Version the version of NetLogo Extension API for which this JAR is intended If a user opens the extension with NetLogo that has a different Extension API version a warning message i
275. les or the patches with pxcor evenly divisible by five or the turtles in the first quadrant that are on a green patch or the links Programming Guide 95 NetLogo 4 0 User Manual connected to turtle 0 These agentsets can then be used by ask or by various reporters that take agentsets as inputs One way is to use turtles here Or turtles at to make an agentset containing only the turtles on my patch or only the turtles on some other particular patch There s also turtles on so you can get the set of turtles standing on a given patch or set of patches or the set of turtles standing on the same patch as a given turtle or set of turtles Here are some more examples of how to make agentsets all other turtles other turtles all other turtles on this patch other turtles here all red turtles turtles with color red all red turtles on my patch turtles here with color red 7 patches on right side of view patches with pxcor gt 0 all turtles less than 3 patches away turtles in radius 3 the four patches to the east north west and south patches at points 1 0 0 1 1 0 0 1 Shorthand for those four patches neighbors4 7 turtles in the first quadrant that are on a green patch turtles with xcor gt 0 and ycor gt 0 and pcolor green 7 turtles standing on my neighboring four patches turtles on neighbors4 7 all the links connected to turtle 0 my links of turtle 0
276. les off of patch centers in the first place The sprout command creates turtles on patch centers For example ask n of 50 patches sprout 1 face one of neighbors4 Another way for a turtle to start on a patch center is with a command such as this line of turtle code which moves it to the center of a random patch move to one of patches Once a turtle is on a patch center as long as its heading always stays an exact multiple of 90 that is to say due north east south or west and as it long as it moves forward or back by integer amounis it will always land on patch centers See Random Grid Walk Example in the Code Examples section of the Models Library to see these code snippets in use patch ahead 1 is reporting the same patch my turtle is already standing on Why See the answer two answers up It s the same issue This might not be the meaning of ahead you were expecting With patch ahead you must specify the distance ahead that you want to look If you want to know the next patch a turtle would cross into if it moved forward continuously it is possible to find that out See Next Patch Example in the Code Examples section of the Models Library How do give my turtles vision You can use in radius to let a turtle see a circular area around it Several primitives let the turtle look at specific points The pat ch ahead primitive is useful for letting a turtle see what is directly in front of it If you want
277. lf its whole life Let s change a random wolf into a sheep ask one of wolves set breed sheep The set default shape primitive is useful for associating certain turtle shapes with certain breeds See the section on shapes below Here is a quick example of using breeds breed mice mouse breed frogs frog mice own cheese to setup clear all create mice 50 set color white set cheese random 10 create frogs 50 set color green end Code Example Breeds and Shapes Example Link Breeds Link breeds are very similar to turtle breeds however there are a few differences When you declare a link breed you must declare whether it is a breed of directed or undirected links by using the directed 1ink breed and undirected link breed keywords directed link breed streets street undirected link breed friendships friendship 98 Programming Guide NetLogo 4 0 User Manual once you have created a breeded link you cannot create unbreeded links and vice versa You can however have directed and undirected links in the same world just not in the same breed Unlike with turtle breeds the singular breed name is required for link breeds as many of the link commands and reports use the singular name such as lt 1ink breed gt neighbor The following primitives are also automatically available once you define a directed link breed create street from create streets from create street to create streets t
278. ll so dark they appear black e 19 9 29 9 and so on are all so light they appear white Code Example The color chart was made in NetLogo with the Color Chart Example model If you use a number outside the 0 to 140 range NetLogo will repeatedly add or subtract 140 from the number until it is in the O to 140 range For example 25 is orange so 165 305 445 and so on are orange too and so are 115 255 395 etc This calculation is done automatically whenever you set the turtle variable color or the patch variable pcolor Should you need to perform this calculation in some other context use the wrap color primitive If you want a color that s not on the chart more can be found between the integers For example 26 5 is a shade of orange halfway between 26 and 27 This doesn t mean you can make any color in NetLogo the NetLogo color space is only a subset of all possible colors It contains only a fixed set of discrete hues one hue per row of the chart Starting from one of those hues you can either decrease its brightness darken it or decrease its saturation lighten it but you cannot decrease both brightness and saturation Also only the first digit after the decimal point is significant Thus color values are rounded down to the next 0 1 so for example there s no visible difference between 26 5 and 26 52 or 26 58 Color primitives There are a few primitives that are helpful for working with colors We have already ment
279. lled unstable if it tends to result in extinction for one or more species involved In contrast a system is stable if it tends to maintain itself over time despite fluctuations in population sizes There nre tan main varintinns n this mndel You can edit the text in this view as in any text editor However a few different forms will be displayed specially when you switch out of the edit view Information Tab Markup Lines that come after blank lines and contain capital letters and no lower case letters WHAT IS IT WHAT IS IT become section headers Any line that has only dashes is omitted Anything beginning with http becomes http ccl northwestern edu http ccl northwestern edu a clickable hyperlink E mail addresses become clickable bugs ccl northwestern edu bugs ccl northwestern edu mailto links Lines that begin with this is preformatted text this is preformatted text the pipe shift you can put spacesin it cem Pee spaces in it backslash Y become monospaced text This is useful for diagrams and complicated 82 Interface Guide NetLogo 4 0 User Manual formulas among other things To return to the normal view click the edit button Procedures Tab This tab is the workspace where the code for the model is stored Commands you only want to use immediately go in the Command Center commands you want to save and use later over and over again are found in the Pr
280. llows you to edit various model properties Continuous updates means that NetLogo updates that is redraws the view many times a second regardless of what is going on in the model Tick based updates means that the view only updates when the tick counter advances For a fuller discussion of view updates see the Programming Guide The 2D and 3D Views The large black square in the Interface tab is the 2D view It s a visual representation of the NetLogo world of turtles and patches Initially it s all black because the patches are black and there are no turtles yet You can open the 3D View another visual representation of the world by clicking on the 3D button in the View Control Strip ROL ticks 0 30 The three sets of black arrows in the upper left let you change the size of the world When the origin is centered the world will grow in increments of two adding one to the maximum and subtracting one from the minimum If one of the edges is set to O the world will grow by one in the other direction to keep the origin along the edge If the origin is at a custom location the black arrows will be disabled There are a number of settings associated with the Views There are a few ways of changing the settings by using the control strip along the top edge of the View or by editing the 2D View as described in the Working With Interface Elements section above or pressing the Settings button in the toolbar Notice that th
281. ls see java sun com Extensions Guide 191 NetLogo 4 0 User Manual 5 Use your extension in a model To use our example extension put the example folder in the NetLogo extensions folder or in the same directory as the model that will use the extension At the top of the Procedures tab write extensions example Now you can use example first n integers Just like it was a built in NetLogo reporter For example select the Interface tab and type in the Command Center observer gt show example first n integers 5 observer 0 1 2 3 4 Extension development tips Instantiation Your class manager is instantiated at the time a model using the extension is loaded Command and reporter objects are instantiated whenever NetLogo code is compiled that uses your commands and reporters Classpath Don t forget to include NetLogo jar in your class path when compiling This is the most common mistake made by new extension authors If the compiler can t find NetLogo jar you ll get error messages about classes in the org nlogo api package not being found Debugging extensions There are special NetLogo primitives to help you as you develop and debug your extension These are considered experimental and may be changed at a later date That s why they have underscores in their name eprint _ dump extensions prints information about loaded extensions print __dump extension prims prints information about loaded extension primitives
282. lt in turtle variables like color To make a new turtle variable we add a turtles own declaration at the top of the Procedures tab before all the procedures Call it energy turtles own energy Tutorial 3 Procedures 53 NetLogo 4 0 User Manual to go move turtles eat grass end Let s use this newly defined variable energy to allow the turtles to eat e Switch to the Procedures tab e Rewrite the go procedure as follows to go move turtles Sat grass end e Add a new eat grass procedure to est grass ask turtles if pcolor green set pcolor black set energy energy 10 We are using the if command for the first time Look at the code carefully Each turtle when it runs these commands compares the value of the patch color it is on pcolor to the value for green A turtle has direct access to the variables of the patch it is standing on If the patch color is green the comparison reports t rue and only then will the turtle runs the commands inside the brackets otherwise it skips them The commands make the turtle change the patch color to black and increase its own energy by 10 The patch turns black to signify that the grass at that spot has been eaten and the turtle is given more energy from having just eaten the grass Next let s make the movement of turtles use up some of the turtle s energy e Rewrite move turtles as follows to move turtles ask turtles right random 360 forward 1 s
283. ltReporter take one number as input report a list public Syntax getSyntax return Syntax reporterSyntax new int Syntax TYPE_NUMBER Syntax TYPE_LIST y public Object report Argument args Context context throws ExtensionException create a NetLogo list for the result LogoList list new LogoList int n use typesafe helper method from org nlogo api Argument to access argument Extensions Guide 189 NetLogo 4 0 User Manual try n args 0 getIntValue catch LogoException e throw new ExtensionException e getMessage if n lt 0 signals a NetLogo runtime error to the modeler throw new ExtensionException input must be positive populate the list note that we use Double objects NetLogo numbers are always doubles for int i 0 i lt n itt list add new Double i return list Notice e Note that the number objects we put in the list are Doubles not Integers All numbers used as NetLogo values must be of type Double even if they happen to have no fractional part e To access arguments use org nlogo api Argument s typesafe helper methods such as getDoubleValue e Throw org nlogo api ExtensionException to signal a NetLogo runtime error to the modeler A Command is just like a Reporter except that reporters implement Object report while commands imp
284. lygon formed by its linked neighbors The centroid is like a 2 dimensional average of the coordinates of the neighbors The purpose of the circle of anchor agents is to prevent all the turtles from collapsing down to one point After a few iterations of this the layout will stabilize This layout is named after the mathematician William Thomas Tutte who proposed it as a method for graph layout to make a tree set default shape turtles circle crt 6 ask turtle 0 create link with turtle 1 create link with turtle 2 create link with turtle 3 284 NetLogo Dictionary NetLogo 4 0 User Manual ask turtle 1 create link with turtle 4 create link with turtle 5 place all the turtles with just one neighbor on the perimeter of a circle and then place the remaining turtles inside this circle spread between their neighbors repeat 10 layout tutte turtles turtles with count link neighbors 1 12 end left It left number The turtle turns left by number degrees If number is negative it turns right length length list length string Reports the number of items in the given list or the number of characters in the given string let let variable value Creates a new local variable and gives it the given value A local variable is one that exists only within the enclosing block of commands If you want to change the value afterwards use set Example let prey one of s
285. may be an integer or a floating point number Some models divide ticks more finely than by ones The input may not be negative See also tick ticks reset ticks ticks ticks Reports the current value of the tick counter The result is always a number and never negative Most models use the tick command to advance the tick counter in which case ticks will always report an integer If the tick advance command is used then ticks may report a floating point number See also tick tick advance reset ticks tie tie P Ties end2 and end2 of the link together If the link is a directed link end is the root turtle and end2 is the leaf turtle The movement of the root turtle affects the location and heading of the leaf turtle If the link is undirected the tie is reciprocal so both turtles can be considered root turtles and leaf turtles Movement or change in heading of either turtle affects the location and heading of the other turtle When the root turtle moves the leaf turtles moves the same distance in the same direction The heading of the leaf turtle is not affected This works with forward jump and setting the xcor or ycor of the root turtle When the root turtle turns right or left the leaf turtle is rotated around the root turtle the same amount The heading of the leaf turtle is also changed by the same amount If the link dies the tie relation is removed ert 2 fd 3 7 Creates a link and ties turtle 1 to turtle 0
286. mbinations you wish Programming Guide 123 NetLogo 4 0 User Manual given that the point 0 0 still exists in the world If you are logically only modeling in one or two quadrants or if it makes your code simpler to only use positive numbers you might want to consider changing your model If you ve modeled something that requires and even grid you ll certainly want to remove the programming hacks required to make that possible in the past Code Examples Lattice Gas Automaton Binomial Rabbits Rugby For NetLogo 3 1 we added new primitives which are essential if you change the topology and quite convenient even if you don t random pxcor random pycor random xcor and_random ycor report random values within the range between maximum and minimum x and y In older versions of NetLogo we often relied on wrapping to place turtles randomly across the world by writing set xy random float screen size x random float screen size y However if wrapping is not allowed in one direction or the other this no longer works you get a runtime error for trying to place turtles outside the world Regardless of topology it is simpler and more straight forward to use setxy random xcor random ycor instead To convert a model to use a topology you must first decide what settings best describe the world If the answer is not immediately obvious to you based on the real world a room is a box a wire is a cylinder there are a few clues that will help you If
287. mes 0 the new commands have somewhat different semantics that are less prone to problems models using the old reporters will require hand changes new reporters no turtles no patches and no links report empty agentsets two agentsets can now be tested for equality the tie and untie commands are no longer experimental they now take no inputs and can only be used by links two tie modes are available fixed and free the operator only adds numbers now it doesn t work on strings or lists anymore models must be changed by hand to use word instead for strings and sentence instead for numbers new histogram command replaces old histogram 1ist histogram from commands removed random int or float from the language some models may need to be changed by hand to use random or random float instead 11 NetLogo 4 0 User Manual removed nsum and nsum4 from language use sum reporter of neighbors neighbors4 instead new agentset primitives min n of and max n of new primitive with local randomness runs code without altering the state of the random number generator new file I O primitive fi1e f1ush forces output to disk new color primitive base colors reports a list of the 14 basic NetLogo hues the turtle primitive no longer accepts non integer inputs the patch primitive now accepts non integers and rounds them and also wraps if allowed the observer may no longer use patch at turtles at and BREED at use patc
288. mmands in an observer button that does ask turtles ask patches or ask links An ask doesn t complete until all of the agents have finished running all of the commands in the ask So the agents as they all run the commands concurrently can be out of sync with each other but they all sync up again at the end of the ask The same isn t true of turtle patch and link forever buttons Since ask was not used each turtle or patch runs the given code over and over again so they can become and remain out of sync with each other At present this capability is very rarely used in the models in our Models Library A model that does use the capability is the Termites model in the Biology section of Sample Models The go button is a turtle forever button so each termite proceeds independently of every other termite and the observer is not involved at all This means that if for example you wanted to add a plot to the model you would need to add a second forever button an observer forever button and run both forever buttons at the same time At present NetLogo has no way for one forever button to start another Buttons are only started when you press them 100 Programming Guide NetLogo 4 0 User Manual Lists In the simplest models each variable holds only one piece of information usually a number or a string The list feature lets you store multiple pieces of information in a single variable by collecting those pieces of information in
289. mmands is used to control the NetLogo feature of auto plotting in the current plot Auto plotting will automatically update the x and y axes of the plot whenever the current pen exceeds these boundaries It is useful when wanting to show all plotted values in the current plot regardless of the current plot ranges B back bk back number The turtle moves backward by number steps If number is negative the turtle moves forward Turtles using this primitive can move a maximum of one unit per time increment So bk 0 5 and bk 1 both take one unit of time but bk 3 takes three NetLogo Dictionary 243 NetLogo 4 0 User Manual If the turtle cannot move backward number steps because it is not permitted by the current topology the turtle will complete as many steps of 1 as it can and stop See also forward jump can move base colors base colors Reports a list of the 14 basic NetLogo hues print base colors gt 5 15 25 35 45 55 65 75 85 95 105 115 125 135 ask turtles set color one of base colors each turtle turns a random base color ask turtles set color one of remove gray base colors 7 each turtle turns a random base color except for gray beep beep Emits a beep Note that the beep sounds immediately so several beep commands in close succession may produce only one audible sound Example beep emits one beep repeat 3 beep 7 emits 3 beeps at once 77 so you only hear one sound re
290. n value from and values from with a single of construct no hyphen new lor of turtle 0 color of turtle 0 size size of turtle 0 lue from turtle 0 size size mean values from turtles size mean size of turtles Transition Guide 137 NetLogo 4 0 User Manual When of is used with a single agent it reports a single value When used with an agentset it reports a list of values in random order since agentsets are always in random order Note that when opening old models in the new version of value from and values from will automatically be converted to use of instead but some nested uses of these constructs are too complex for the converter and must be converted by hand Serial ask The ask command is now serial rather than concurrent In other words the asked agents will run one at a time Not until one agent completely finishes the entire body of the ask does the next agent start Note that even the old ask was never truly concurrent we simulated concurrent execution by interleaving execution among the agents using a turn taking mechanism described in the NetLogo FAQ We have made this change because in our experience users often wrote models that behaved in unexpected ways due to the simulated concurrency but rarely wrote models that benefited from the simulated concurrency Models exhibiting unexpected behavior could usually be fixed by adding the without interrupt ion command in the right
291. n a line bar or point will be drawn depending on the pen s mode plot x min plot x max plot y min plot y max plot x min plot x max plot y min plot y max Reports the minimum or maximum value on the x or y axis of the current plot These values can be set with the commands set plot x range and set plot y range Their default values are set from the plot Edit dialog position position item list position string1 string2 On a list reports the first position of item in list or false if it does not appear On strings reports the position of the first appearance string1 as a substring of string2 or false if it does not appear Note The positions are numbered beginning with 0 not with 1 7 suppose mylist is 2 7 4 7 Bob show position 7 mylist gt 1 show position 10 mylist gt false show position in string gt 3 See also_member precision precision number places Reports number rounded to places decimal places NetLogo Dictionary 309 NetLogo 4 0 User Manual If places is negative the rounding takes place to the left of the decimal point show precision 1 23456789 3 gt 1 235 show precision 3834 3 gt 4000 print print value Prints value in the Command Center followed by a carriage return The calling agent is not printed before the value unlike_show See also_show type and_write See also output print pxcor pycor pxcor BR A These are built in pat
292. n Bakshy To refer to this package in academic publications please use Bakshy E Wilensky U 2007 NetLogo Mathematica Link http ccl northwestern edu netlogo mathematica html Center for Connected Learning and Computer Based Modeling Northwestern University Evanston IL Mathematica Link 185 NetLogo 4 0 User Manual 186 Mathematica Link Extensions Guide NetLogo allows users to write new commands and reporters in Java and use them in their models This section of the User Manual introduces this facility The first part discusses how to use an extension in your model once you have written one or once someone has given you one The second part is intended for Java programmers interested in writing their own extensions using the NetLogo Extension API e Using Extensions e Writing Extensions The NetLogo Extension API Specification contains further details Using Extensions To use an extension in a model add the extensions keyword at the beginning of the Procedures tab before declaring any breeds or variables After extensions comes a list of extension names in square brackets For example extensions sound speech Using extensions tells NetLogo to find and open the specified extension and makes the custom commands and reporters found in the extension available to the current model You can use these commands and reporters just as if they were built in NetLogo primitives Where extensions are located NetLogo w
293. n monitors won t affect model run reproducibility the run and runresult primitives are now drastically faster when called repeatedly on the same string the display command now works even when used by a turtle patch or link 4 internally lists are now linked lists not arrays this does not affect the behavior of models but may affect performance positively or negatively depending on what list operations you are doing see Programming Guide when turtles move in a way that does not indicate direction e g set xy the shortest path is now always drawn even if it wraps 4 fixed bug where in some conditions exporting and then re importing the world during a model run could alter the outcome by affecting how who numbers were reused e What s New NetLogo 4 0 User Manual the sort by primitive is now stable that is it does not disturb the existing order of equal items the file read primitive is now much faster at reading very long lists 4 fixed bugs where in cone and distance didn t work properly in some topologies fixed bug where some layout commands were not controlled by the random seed the global variables associated with sliders switches choices and input boxes now behave the same when running headless as in the GUI that is they reject values that are of the wrong type or out of range e other fixes the Halt item on the Tools menu now works in more sit
294. n the Interface A dialog box will appear Tutorial 3 Procedures 57 NetLogo 4 0 User Manual e In the Global variable section of the dialog box type show energy Don t forget to include the question mark in the name See image below Mays ticks 0 setup go y count turtles 50 green patches 1225 000 Switch Global variable show energy e Now go back to the go procedure using the Procedures tab with the Toolbar e Rewrite the eat grass procedure as follows to est grass ask turtles if pcolor green set pcolor black set energy energy 10 ifelse show energy set label energy set label The eat grass procedure introduces the ifelse command Look at the code carefully Each turtle when it runs these new commands checks the value of show energy determined by the switch If the switch is on comparison is true and the turtle will run the commands inside the first set of brackets In this case it assigns the value for the energy to the label of the turtle If the comparison is false the switch is off then the turtle runs the commands inside the second set of brackets In this case it removes the text labels by setting the label of the turtle to be nothing In NetLogo a piece of text is called a string A string is a sequence of letters and other characters written between double quotes Here we have two double quotes right next to each o
295. n window is divided into tabs e Menus e Tabs e Interface Tab Working with Interface Elements The 2D and 3D Views Command Center Plots e Information Tab e Procedures Tab e Includes Menu Menus On Macs if you are running the NetLogo application the menubar is located at the top of the screen On other platforms the menubar is found at the top of the NetLogo window File Edit Tools Zoom Tabs Help NetLogo Untitled The functions available from the menus in the menubar are listed in the following chart Chart NetLogo Menus Z D Open Models Librar Save Save As Save the current model using a different name Save As Applet Used to save a web page in HTML format that has your model embedded in it as a Java applet Print Sends the contents of the currently showing tab to your printer Export World Saves all variables the current state of all turtles and patches the drawing the plots the output area and the random state information to a file Export Plot Saves the data in a plot to a file Export All Plots Saves the data in all the plots to a file Interface Guide 69 NetLogo 4 0 User Manual ExportView Save a picture of the current view 2D or 3D to a file in PNG format Export Interface Save a picture of the current Interface tab in PNG format Export Output Save the contents of the output area or the output section of the command center to a file Import World Load a file that
296. n writing mode See also file close file print file print value Prints value to an opened file followed by a carriage return The calling agent is not printed before the value unlike file show Note that this command is the file i o equivalent of print and file open needs to be called before this command can be used See also file show file type and file write file read file read This reporter will read in the next constant from the opened file and interpret it as if it had been typed in the Command Center It reports the resulting value The result may be a number list string boolean or the special value nobody Whitespace separates the constants Each call to file read will skip past both leading and trailing whitespace Note that strings need to have quotes around them Use the command file write to have quotes included Also note that the file open command must be called before this reporter can be used and there must be data remaining in the file Use the reporter filge at end to determine if you are at the end of the file file open my file data NetLogo Dictionary 263 NetLogo 4 0 User Manual print file read 5 7 Next value is the number 1 gt 6 print length file read 7 Next value is the list 1 2 3 4 gt 4 See also file open and file write file read characters file read characters number Reports the given number of characters from an opened file as a string If there are
297. nd y values of all points plotted by all the plot pens in the plot given by the string plotname to an external file given by the string filename If a pen is in bar mode mode 0 and the y value of the point plotted is greater than 0 the upper left corner point of the bar will be exported If the y value is less than 0 then the lower left corner point of the bar will be exported export all plots writes every plot in the current model to an external file given by the string filename Each plot is identical in format to the output of export plot export world writes the values of all variables both built in and user defined including all observer turtle and patch variables the drawing the contents of the output area if one exists the contents of any plots and the state of the random number generator to an external file given by the string filename The result file can be read back into NetLogo with the import world primitive export world does not save the state of open files export plot export all plots and export world save files in in plain text comma separated values csv format CSV files can be read by most popular spreadsheet and database programs as well as any text editor If the file already exists it is overwritten If you wish to export to a file in a location other than the model s location you should include the full path to the file you wish to export Use the forward slash as the folder separator Note th
298. ng as a path name to a file and open the file You may then use the reporters file read file read line and file read characters to read in from the file or file write file print file type or file show to write out to the file Note that you can only open a file for reading or writing but not both The next file i o primitive you use after this command dictates which mode the file is opened in To switch modes you need to close the file using file close Also the file must already exist if opening a file in reading mode 262 NetLogo Dictionary NetLogo 4 0 User Manual When opening a file in writing mode all new data will be appended to the end of the original file If there is no original file a new blank file will be created in its place You must have write permission in the file s directory If you don t want to append but want to replace the file s existing contents use file delete to delete it first perhaps inside a carefully if you re not sure whether it already exists Note that the string can either be a file name or an absolute file path If it is a file name it looks in whatever the current directory is This can be changed using the command set current directory It is defaulted to the model s directory file open my file in txt print file read line gt First line in file File is in reading mode file open C NetLogo my file out txt assuming Windows machine file print Hello World File is i
299. nguage Eventually you ll be ready for Tutorial 3 Procedures where you can learn how to alter and extend existing models to give them new behaviors and build your own models 26 Sample Model Party Tutorial 1 Models If you read the Sample Model Party section you got a brief introduction to what it s like to interact with a NetLogo model This section will go into more depth about the features that are available while you re exploring the models in the Models Library Throughout all of the tutorials we ll be asking you to make predictions about what the effects of making changes to the models will be Keep in mind that the effects are often surprising We think these surprises are exciting and provide excellent opportunities for learning Some people have found it helpful to print out the tutorials in order to work through them When the tutorials are printed out there s more room on your computer screen for the NetLogo model you re looking at Sample Model Wolf Sheep Predation We ll open one of the Sample Models and explore it in detail Let s try a biology model Wolf Sheep Predation a predator prey population model e Open the Models Library from the File menu NetLogo HEM Edit Tools Zoon a New 3N tl 0 3 Open Models Library 3M 3 Save 3S E Save AS Save As Applet Print dE P e Choose Wolf Sheep Predation from the Biology section and press Open The Interface tab will fill up w
300. nks 7 prints the number of links 286 NetLogo Dictionary NetLogo 4 0 User Manual links own lt link breeds gt own links own var7 lt link breeds gt own var The links own keyword like the globals breed lt breeds gt own turiles own and patches own keywords can only be used at the beginning of a program before any function definitions It defines the variables belonging to each link If you specify a breed instead of links only links of that breed have the listed variables More than one breed may list the same variable undirected link breed sidewalks sidewalk directed link breed streets street links own traffic 7 applies to all breeds sidewalks own pedestrians streets own cars bikes list list valuel value2 list value Reports a list containing the given items The items can be of any type produced by any kind of reporter show list random 10 random 10 gt 4 9 or similar list show list 5 gt 5 show list random 10 1 2 3 random 10 gt 4 1 2 3 9 77 or similar list In In number Reports the natural logarithm of number that is the logarithm to the base e 2 71828 See also_e log log log number base Reports the logarithm of number in base base show log 64 2 gt 6 NetLogo Dictionary 287 NetLogo 4 0 User Manual See also In loop loop commands Runs the list of commands forever or until the current procedu
301. nnonnnnnnnenoneneness Curricular Models uo is Monitors Feedback Questions Ele arara Agents and procedures eee Making the setup DU LON oocccccccccccncnnncnnncnnnnnnnnnnnnnnnnnnnnnnnnnonononnnnnnincnnnnoss Making tne go DUtON cs css E a AE EEE ERRES Experimenting with commands erre eeareererereea Patches and variables ida TUS variaDISS li a a a T aaa a a a tank bene reer Switches and ME E E dd eee OS 21 NetLogo 4 0 User Manual Table of Contents Tutorial 3 Procedures Whats Mex A NR SN RE NS SE ER 65 Appendix Complete COD usas asneira afeitar iia 66 Interface GUIA ss sds sacia acs Se ce sec dna foda btw S E ck coke Sa aa oa E ES Sima Goa ai aih E ani eeetewe 69 Men US in A a ot ech eae Maan o Tel aes 69 DAS sta deitada cal iria GU a SGA E IA a ADA A Re aE BRE E A 71 Interiace Tah o em Ste eden sas E cas de 72 Working with Interface EleMentS ooococcncccnnnooooccccnnonccconnonononononcnnonnnonnonnnnnnnnnnnarnnnnnnnnnnn 72 Chart Interface Toolbar tr eererr iiaiai Takarina 73 Thee Diand SD VIEWS sas cesses st a a wecteatan nan cada 74 Gommand Genter us O or le ee 78 O a ee E 80 hed Ke see eee E STR EE E E UD ae RO E Tee 81 Information Taba Soc ie ie te eae A Me eae tt Nee Siti ale ies ies cies ees tice pa in Red dad 81 Information Tab MAU sq rasante na Sa da nai UN a AASP dd Raio pad 82 WHALIS AT oe loa 82 Brocedures Tab sasua it a TI dO doado A a dd
302. not wait for the note to finish before continuing to next command 7 in one second play a trumpet at middle C for two seconds sound play note later 1 TRUMPET 60 64 2 sound play sound sound play sound filename Plays a sound file It does not wait for the sound file to finish before moving to the next command It supports WAV AIFF and AU files 7 plays the beep wav sample file sound play sound beep wav 200 Sound Extension NetLogo 4 0 User Manual sound play sound and wait sound play sound and wait filename Plays a sound file waiting for it to finish playing before moving to the next command It supports WAV AIFF and AU files 7 plays the beep wav sample file waiting for it to finish before 7 playing boop wav sound play sound and wait beep wav sound play sound and wait boop wav sound play sound later sound play sound later filename delay Plays a sound file after the specified delay in seconds It does not wait for the sound file to play or finish before moving to the next command It supports WAV AIFF and AU files plays the beep wav sample file one second from now sound play sound later beep wav 1 sound start note sound start note instrument keynumber velocity Starts a note The note will continue until sound stop note sound stop instrument or sound stop music is called 7 play a violin at middle C sound start note VIOLIN 60 64 7 play a C major scale on a xylophone
303. nt to compress your movies with third party software The software may give you a choice of different kinds of compression Some kinds of compression are lossless while others are lossy Lossy means that in order to make the files smaller some of the detail in the movie is lost Depending on the nature of your model you may want to avoid using lossy compression for example if the view contains fine pixel level detail One software package that can compress QuickTime movies on both the Mac and Windows platforms is QuickTime Pro On Macs iMovie works as well Perspective The 2D and the 3D view show the world from the perspective of the observer By default the observer is looking down on the world from the positive z axis at the origin You can change the perspective of the observer by using the follow ride and watch observer commands and follow me ride me and watch me turtle commands When in follow or ride mode the observer moves with the subject agent around the world The difference between follow and ride is only visible in the 3D view In the 3D view the user can change the distance behind the agent using the mouse When the observer is following at zero distance from the agent it is actually riding the agent When the observer is in watch mode it tracks the movements of one turtle without moving In both views you will see a spotlight appear on the subject and in the 3D view the observer will turn to face the subject To determine which
304. nt setup then there is no need to specify them on the command line Note also the use of the optional no results argument to specify that no output is to be generated This is useful if the experiment setup generates all the output you need by some other means such as exporting world files or writing to a text file Yet another example java server Xmsl16M Xmx1024M cp NetLogo jar org nlogo headless HeadlessWorkspace model Fire nlogo xperiment experiment2 table table output csv spreadsheet spreadsheet output csv The optional table lt filename gt argument specifies that output should be generated in a table format and written to the given file as CSV data If is specified as the filename than the output is sent to the standard system output stream Table data is written as it is generated with each complete run The optional spreadsheet lt filename gt argument specified that soreadsheet output should be generated and written to the given file as CSV data If is specified as the filename than the output is sent to the standard system output stream Spreadsheet data is not written out until all runs in the experiment are finished Note that it is legal to specify both table and spreadsheet and if you do both kinds of output file will be generated The default output behavior when no output formats are specified is to send table output to the system standard output stream
305. ntally Y World wraps vertically View Patch size 9 Font size 14 measured in pixels of labels on agents M Turtle shapes ifunchecked turtles appear as squares Tick counter Y Show tick counter Tick counter label ticks Cancel Apply What are the current settings for max pxcor min pxcor max pycor min pycor and Patch size e Press cancel to make this window go away without changing the settings e Place your mouse pointer next to but still outside of the view Tutorial 1 Models 33 NetLogo 4 0 User Manual You will notice that the pointer turns into a crosshair e Hold down the mouse button and drag the crosshair over the view The view is now selected which you know because it is now surrounded by a gray border e Drag one of the square black handles The handles are found on the edges and at the corners of the view e Unselect the view by clicking anywhere in the white background of the Interface tab e Press the Settings button again and look at the settings What numbers changed What numbers didn t change The NetLogo world is a two dimensional grid of patches Patches are the individual squares in the grid In Wolf Sheep Predation when the grass switch is on the individual patches are easily seen because some of them are green while others are brown Think of the patches as being like square tiles in a room with a tile floor By default exactly in the middl
306. ntie Unties end2 from end sets tie mode to none if they were previously tied together If the link is an undirected link then it will untie end7 from end2 as well It does not remove the link between the two turtles See also tie See the Tie section of the Programming Guide for more details uphill uphill4 uphill patch variable _ patch variable Moves the turtle to the neighboring patch with the highest value for patch variable If no neighboring patch has a higher value than the current patch the turtle stays put If there are multiple patches with the same highest value the turtle picks one randomly Non numeric values are ignored uphill considers the eight neighboring patches uphill4 only considers the four neighbors Equivalent to the following code assumes variable values are numeric move to patch here go to patch center let p max one of neighbors patch variable or neighbors4 if patch variable of p gt patch variable face p move to p Note that the turtle always ends up on a patch center and has a heading that is a multiple of 45 uphill or 90 uphill4 NetLogo Dictionary 337 NetLogo 4 0 User Manual See also_uphill uphill4 user directory user directory Opens a dialog that allows the user to choose an existing directory on the system It reports a string with the absolute path or false if the user cancels set current directory user directory 7 Assumes the user will choos
307. ntly of the switch in the view control strip that freezes the view See also display nobody nobody This is a special value which some primitives such as turtle one of max one of etc report to indicate that no agent was found Also when a turtle dies it becomes equal to nobody Note Empty agentsets are not equal to nobody If you want to test for an empty agentset use any 2 You only get nobody back in situations where you were expecting a single agent not a whole agentset set other one of other turtles here 1f other nobody ask other set color red no links no links Reports an empty link agentset NetLogo Dictionary 299 NetLogo 4 0 User Manual no patches no patches Reports an empty patch agentset not not boolean Reports true if boolean is false otherwise reports false 1f not any turtles crt 10 no turtles no turtles Reports an empty turtles agentset O of reporter of agent reporter of agentset For an agent reports the value of the reporter for that agent turtle or patch show pxcor of patch 3 5 7 prints 3 show pxcor of one of patches 7 prints the value of a random patch s pxcor variable show who who of turtle 5 gt 25 show count turtles in radius 3 of patch 0 0 7 prints the number of turtles located within a 7 three patch radius of the origin For an agentset reports a list that contains the value of the reporter for each ag
308. ntosh or right click other systems the element and choose Unselect from the popup menu Editing To change the characteristics of an interface element select the element then press the Edit button on the Interface Toolbar You may also double click the element once it is selected A 72 Interface Guide NetLogo 4 0 User Manual third way to edit an element is to control click Macintosh or right click other systems it and choose Edit from the popup menu If you use this last method it is not necessary to select the element first Moving Select the interface element then drag it with your mouse to its new location If you hold down the shift key while dragging the element will move only straight up and down or straight left and right Resizing Select the interface element then drag the black handles in the selection border Deleting Select the element or elements you want to delete then press the Delete button on the Interface Toolbar You may also delete an element by control clicking Macintosh or right clicking other systems it and choosing Delete from the popup menu If you use this latter method it is not necessary to select the element first To learn more about the different kinds of interface elements refer to the chart below Chart Interface Toolbar Icon amp Name Description ac Button Buttons can be either once only buttons or forever buttons When you click on a once button it executes its
309. nts which can appear on screen in any size or orientation Getting Started To begin making shapes choose Turtle Shapes Editor or Link Shapes Editor in the Tools menu A new window will open listing all the shapes currently in the model beginning with default the default shape The Shapes Editor allows you to edit shapes create new shapes and borrow from another model You can also import turtle shapes from a library of pre existing shapes Importing Shapes Every new model in NetLogo starts off containing a small core set of frequently used shapes Many more turtle shapes are available by using the Import from library button This brings up a dialog where you can select one or more shapes and bring them into your model Select the shapes then press the Import button Similarly you can use the Import from model button to borrow shapes from another model Default shapes Here are the turtle shapes that are included by default in every new NetLogo model First row default airplane arrow box bug butterfly Second row car circle circle 2 cow cylinder dot Third row face happy face neutral face sad fish flag flower Shapes Editor Guide 147 NetLogo 4 0 User Manual Fourth row house leaf line line half pentagon person Fifth row plant square square 2 star target tree Sixth row triangle triangle 2 truck turtle wheel x Shapes library And here are the shapes in the shapes library including all of t
310. nts Info plist file in the NetLogo application package You can reach this file by control clicking the application in the Finder and choosing Show Package Contents from the popup menu The relevant section is this the second number is the ceiling lt key gt VMOpt ions lt key gt lt string gt Xms16M Xmx1024M lt string gt Note that at least as of Mac OS X 10 3 the maximum possible heap size for any Java program is two gigabytes Other Java VMs from Sun let you set the ceiling on the command line as follows If you are using a VM from a different vendor the method may be different Note that we recommend the server flag for best performance in most situations We also recommend setting the noddraw option to true when using the GUI as Direct Draw can conflict with OpenGL java server Dsun java2d noddraw true Xmsl6M Xmx1024M jar NetLogo jar Can import GIS data into NetLogo Yes a number of users have constructed models using raster GIS data We don t know of users who have used vector GIS data other than by converting it to raster data first One simple way is to use import pcolors but that only works for importing maps that are images not maps in other formats 226 FAQ Frequently Asked Questions NetLogo 4 0 User Manual We do not have built in support for reading common GIS formats However a number of our users are working with GIS data successfully using NetLogo code that reads GIS data using our file
311. number is greater than range2 then the lightest shade of color is chosen Note for color shade is irrelevant e g green and green 2 are equivalent and the same spectrum of colors will be used ask turtles set color scale color red age 0 50 7 colors each turtle a shade of red proportional 7 to its value for the age variable NetLogo Dictionary 319 NetLogo 4 0 User Manual self self aH Reports this turtle or patch self and myself are very different self is simple it means me myself means the turtle or patch who asked me to do what I m doing right now See also_myself semicolon comments After a semicolon the rest of the line is ignored This is useful for adding comments to your code text that explains the code to human readers Extra semicolons can be added for visual effect NetLogo s Edit menu has items that let you comment or uncomment whole sections of code sentence se sentence value value2 sentence value Makes a list out of the values If any value is a list its items are included in the result directly rather than being included as a sublist Examples make this clearer how sentence 1 2 1 2 how sentence 1 2 3 1 2 3 how sentence 1 2 3 1 2 3J how sentence 1 2 3 4 1 2 3 4 how sentence 1 2 3 4 1 2 3 4 how sentence 1 2 3 4 5 3 3 7 1 2 3 45 062 Vv Vv Vv Vv v lol aia i atl w i a Vv set se
312. numbers are displayed by NetLogo using scientific notation Examples show 0 000000000001 gt 1 0E 12 show 50000000000000000000 gt 5 0E19 Numbers in scientific notation are distinguished by the presence of the letter E for exponent It means times ten to the power of so for example 1 0E 12 means 1 0 times 10 to the 12 power show 1 00 100 12 gt 1 0E 12 You can also use scientific notation yourself in NetLogo code how 3 0E6 gt 3000000 how 8 123456789E6 gt 8123456 789 how 8 123456789E gt 8 123456789E7 how 3 0E16 3 0E16 how 8 0E 3 0 0080 how 8 0E 4 gt 8 0E 4 v Vv bo lo ila ial wii a These examples show that numbers with fractional parts are displayed using scientific notation if the exponent is less than 3 or greater than 6 Numbers outside of NetLogo s integer range of 9007199254740992 to 9007199254740992 2153 are also always shown in scientific notation show 2 60 gt 1 15292150460684698E18 106 Programming Guide NetLogo 4 0 User Manual When entering a number the letter E may be either upper or lowercase When printing a number NetLogo always uses an uppercase E show 4 5e20 gt 4 5E20 Floating point accuracy Because numbers in NetLogo are subject to the limitations of how floating point numbers are represented in binary you may get answers that are slightly inaccurate For example show 0 1 0 1 0 1 gt 0 3
313. o in street neighbor in street neighbors in street from my in streets my out streets out street neighbor out street neighbors out street to And the following are automatically available when you define an undirected link breed create friendship with create friendships with friendship neighbor friendship neighbors friendship with my friendships Just as with turtle breeds the order in which link breeds are declared defines the order in which the links are drawn so the friendships will always be on top of streets if for some reason these breeds were in the same model You can also use lt link breeds gt own to declare variables of each link breed separately You can change the breed of links like turtles however you cannot the breed of links to be unbreeded links to prevent having breeded and unbreeded links in the same world ask one of friendships set breed streets ask one of friendships set breed links produces a runtime error set default shape may also be used with link breeds to associate it with a particular link shape Code Example Link Breeds Example Buttons Buttons in the interface tab provide an easy way to control the model Typically a model will have at least a setup button to set up the initial state of the world and a go button to make the model run continuously Some models will have additional buttons that perform other actions A button contains some NetLogo code
314. o be histogrammed and set the pen interval either directly with set plot pen interval or indirectly via set histogram num bars to control how many bars that range is split up into Be sure that if you want the histogram drawn with bars that the current pen is in bar mode mode 1 For histogramming purposes the plot s X range is not considered to include the maximum X value Values equal to the maximum X will fall outside of the histogram s range histogram color of turtles draws a histogram showing how many turtles there are 77 of each color home home The calling turtles moves to the origin 0 0 Equivalentto setxy 0 0 hsb hsb hue saturation brightness Reports a RGB list when given a color in HSB format Hue saturation and brightness are integers in the range 0 255 The RGB list contains three integers in the same range 270 NetLogo Dictionary NetLogo 4 0 User Manual See also rgb hubnet broadcast hubnet broadcast tag name value This broadcasts value from NetLogo to the variable in the case of Calculator HubNet or interface element in the case of Computer HubNet with the name tag name to the clients See the_HubNet Authoring Guide for details and instructions hubnet broadcast view hubnet broadcast view This broadcasts the current state of the 2D view in the NetLogo model to all the Computer HubNet Clients It does nothing for Calculator HubNet Note This is an experimental primitive and its beh
315. o be the value of th nergy set label 7 the label is set to an empty text value end to reproduce ask turtles if energy gt birth energy set energy energy birth energy take away birth energy to give birth hatch 1 set energy birth energy give this birth energy to the offspring end to check death ask turtles if energy lt 0 die removes the turtle if it has no energy left end to regrow grass ask patches 3 out of 100 times the patch color is set to green if random 100 lt 3 set pcolor green end to do plots set current plot Totals which plot we want to use next set current plot pen turtles which pen we want to use next plot count turtles what will be plotted by the current pen Tutorial 3 Procedures 67 NetLogo 4 0 User Manual set current plot pen grass which pen we want to use next plot count patches with pcolor green what will be plotted by the current pen end 68 Tutorial 3 Procedures Interface Guide This section of the manual walks you through every element of the NetLogo interface in order and explains its function In NetLogo you have the choice of viewing models found in the Models Library adding to existing models or creating your own models The NetLogo interface was designed to meet all these needs The interface can be divided into two main parts NetLogo menus and the main NetLogo window The mai
316. o purchase a USB to Serial adapter which can be easily found in computer stores with prices ranging from US 15 to US 30 if you have a Mac or Linux machine make sure the adapter is compatible with your platform Mac OS X In order to access the serial ports the user you are logged in as needs to have permission to write to var spool uucp You can run the script gogo lib Mac OS X fix permissions command to set up the permission appropriately It will make that directory writable by the group uucp and then add your current login to that group Double click that file to run it Linux You will need to be able to write the the serial devices normally dev ttys In most Linux distributions this can be set up thru the User Manager Using the GoGo Extension GoGo Extension 205 NetLogo 4 0 User Manual The GoGo Extensions comes preinstalled To use the extension in your model add a line to the top of your procedures tab extension gogo If your model already uses other extensions then it already has an extensions line in it so just add gogo to the list After loading the extension see what ports are available by typing the following into the command center print gogo ports You can open the serial port the GoGo Board is connected to with the gogo open command and see if the board is responding with the ping reporter On Windows gogo open COMI print gogo ping On Linux gogo open dev ttyS01 print gogo ping
317. ocedures tab Interface Information Procedures 214 MEETS Find Check blobals ticks breed sheep a sheep breed wolves wolf turtles onn energy sheep own grabbed used to prevent two wolves from eating the same sheep patches own countdown to setup ca set ticks ask patches set pcolor green if grass indicates whether the grass switch is on if it is true then grass grows and the sheep eat it if it false then the sheep don t need to eat ask patches set countdown random grass regrowth time initialize grass grow clocks randomly if random 2 0 half the patches start out with grass set pcolor brown 3 To determine if the code has any errors you may press the Check button If there are any syntax errors the Procedures tab will turn red and the code that contains the error will be highlighted and a comment will appear in the top box Switching tabs also causes the code to be checked and any errors will be shown so if you switch tabs pressing the Check button first isn t necessary Interface Guide 83 NetLogo 4 0 User Manual Interface Information 9 Find A Check set default shape wolves wolf create custom wolves initial number wolves create the wolves then initialize their set color balck set size 1 5 easier to see set energy random 2 wolf gain from food setxy random float screen size x random float screen size y
318. odel all the sliders and switches are on a default setting If you open a new model or exit the program your changed settings will not be saved unless you choose to save them Note in addition to sliders and switches some models have a third kind of setting called a chooser The Wolf Sheep Predation doesn t have any of these though Gathering Information Plots and Monitors A purpose to modeling is to gather data on a subject or topic that would be very difficult to do in a laboratory situation NetLogo has two main ways of displaying data to the user plots and monitors Plots The plot in Wolf Sheep Predation contains three lines sheep wolves and grass 4 The grass count is divided by four so it doesn t make the plot too tall The lines show what s happening in the model over time To see which line is which click on Pens in the upper right corner of the plot window to open the plot pens legend A key appears that indicates what each line is plotting In this case it s the population counts When a plot gets close to becoming filled up the horizontal axis increases in size and all of the data from before gets squeezed into a smaller space In this way more room is made for the plot to grow If you want to save the data from a plot to view or analyze it in another program you can use the Export Plot item on the File menu lt saves this information to your computer in a format that can by read back by spreadsheet and
319. odel compared distance no wrap to distance to determine whether the next position is wrapped around the world in which case the electron exits the system This is a clever way to solve the problem but unfortunately it is flawed Electrons that wrap in the y direction were also exiting the system which is incorrect in this case The only correct way to exit is to reach the cathode at the left end of the wire If you remove no wrap commands the topology is no longer hard coded into the model so it s easier to test out your model on a different shape of world without a lot of extra coding you may have to add a few extra checks to go from torus to box this is explained more in depth in the How to convert section Note that though we ve removed the no wrap primitives from the dictionary they are still available for you to use we did this so that old models don t have to be changed in order to run How to convert your model When you first open up your model in 3 1 NetLogo will automatically change all cases of screen edge x tomin pxcor and all cases of screen edge x to max pxcor and similarly for y Though this is not directly related to the topology changes you may also want to think about whether moving the origin off center makes sense in your model at this time Before NetLogo 3 1 the world had to be symmetrical around the origin thus the world had to have an odd width and height This is no longer true since you may use any min and max co
320. oes my code have strange characters in it NetLogo only works in en locales A locale is a setting which tells NetLogo which language you are using as well as how to display dates and numbers You may need to switch to to an English locale before launching NetLogo This is usually done in the Regional Settings or Internationalization panel of the operating system FAQ Frequently Asked Questions 229 NetLogo 4 0 User Manual In a future version of NetLogo we plan to support different languages and locales Why do get a runtime error when use setxy random world width random world height It worked before Many models made in NetLogo 3 0 or earlier use this code to scatter turtles randomly using either random Or random float It only works if world wrapping is on Why Because when wrapping is on you can set coordinates of turtles to numbers beyond the edge of the world and NetLogo will wrap the turtle to the other side But in worlds that don t wrap setting the x or y coordinates of a turtle to a point outside the bounds of the world causes a runtime error The world wrap settings were added in NetLogo 3 1 See the Topology section of the Programming Guide for more information To fix your model so that it works regardless of the wrapping settings use one of these two commands instead setxy random xcor random ycor setxy random pxcor random pycor The two commands are a bit different The first command puts the turtle on a
321. of the turtles anywhere in any of the inputs The inputs may be individual turtles turtle agentsets nobody or lists or nested lists containing any of the above turtle set self turtle set self turtles on neighbors turtle set turtle 0 turtle 2 turtle 9 turtle set frogs mice See also patch set link set turtles turtles Reports the agentset consisting of all turtles show count turtles 7 prints the number of turtles turtles at lt breeds gt at turtles at dx dy lt breeds gt at dx dy Reports an agentset containing the turtles on the patch dx dy from the caller including the caller itself if it s a turtle If the caller is the observer dx and dy are calculated from the origin 0 0 7 suppose I have 40 turtles at the origin show count turtles at 0 0 gt 40 If the name of a breed is substituted for turtles then only turtles of that breed are included breed cats cat breed dogs dog create dogs 5 setxy 2 3 show count dogs at 2 3 gt 5 turtles here lt breed gt here 334 NetLogo Dictionary NetLogo 4 0 User Manual turtles here lt breeds gt here Reports an agentset containing all the turtles on the caller s patch including the caller itself if it s a turtle crt 10 ask turtle O show count turtles here gt 10 If the name of a breed is substituted for turtles then only turtles of that breed are included breed cats cat breed dogs dog create cats 5 cr
322. of the variables in a particular turtle You can can also edit the values of the turtle s variables and issue commands to the turtle You can also open a turtle monitor via the View see the View section below Patch Monitor Displays the values of all of the variables in a particular patch You can can also edit the values of the patch s variables and issue commands to the patch You can also open a patch monitor via the View see the View section below 70 Interface Guide NetLogo 4 0 User Manual Link Monitor Displays the values of all of the variables in a particular link You can can also edit the values of the link s variables and issue commands to the link You can also open a link monitor via the View see the View section below Command Center center can also be shown or hidden or resized with the mouse fDView Opens the 3D view See the View section for more information Color Swatches Opens the Color Swatches See the Color Section of the Programming Guide for details Turtle Shapes Draw turtle shapes See the Shapes Editor Guide for more information Editor Link Shapes Editor Draw link shapes See the Shapes Editor Guide for more information BehaviorSpace Guide for more information Modeler Modeler Guide for more details HubNet Client Opens the HubNet Client Editor See the HubNet Authoring Guide for Editor more details HubNet Control Disabled if no HubNet activity is open See the HubNet Guide fo
323. of the world while retaining the original aspect ratio of the image The image is centered in the drawing The old drawing is not cleared first Agents cannot sense the drawing so they cannot interact with or process images imported by import drawing If you need agents to sense an image use import pcolors or import pcolors rgb The following image file formats are supported BMP JPG GIF and PNG If the image format supports transparency alpha that information will be imported as well import pcolors import pcolors filename Reads an image file scales it to the same dimensions as the patch grid while maintaining the original aspect ratio of the image and transfers the resulting pixel colors to the patches The image is centered in the patch grid The resulting patch colors may be distorted since the NetLogo color space does not include all possible colors See the Color section of the Programming Guide import pcolors may be slow for some images particularly when you have many patches and a large NetLogo Dictionary 275 NetLogo 4 0 User Manual image with many different colors Since import pcolors sets the pcolor of patches agents can sense the image This is useful if agents need to analyze process or otherwise interact with the image If you want to simply display a static backdrop without color distortion see_import drawing The following image file formats are supported BMP JPG GIF and PNG If the image form
324. ogo Dictionary 307 NetLogo 4 0 User Manual mao K This is a built in patch variable It holds a number greater than or equal to 0 and less than 140 This number determines what color the patch s label appears in if it has a label You can set this variable to change the color of a patch s label All patch variables can be directly accessed by any turtle standing on the patch See also_plabel label label color plot plot number Increments the x value of the plot pen by plot pen interval then plots a point at the updated x value and a y value of number The first time the command is used on a plot the point plotted has an x value of 0 plot name plot name Reports the name of the current plot a string plot pen exists plot pen exists string Reports true if a plot pen with the given name is defined in the current plot Otherwise reports false plot pen down plot pen up plot pen down plot pen up Puts down or up the current plot pen so that it draws or doesn t By default all pens are down initially plot pen reset plot pen reset Clears everything the current plot pen has drawn moves it to 0 0 and puts it down If the pen is a permanent pen the color and mode are reset to the default values from the plot Edit dialog 308 NetLogo Dictionary NetLogo 4 0 User Manual plotxy plotxy number number2 Moves the current plot pen to the point with coordinates number1 number2 If the pen is dow
325. ond On the fastest setting updates will be separated by several seconds At extremely slow settings NetLogo will be updating so often that you will see your agents moving or changing color etc one at a time If you need to temporarily shut off continuous updates use the no display command The display command turns updates back on and also forces an immediate update unless the user is fast forwarding the model using the speed slider Tick based updates As discussed above in the_Tick Counter section in many NetLogo models time passes in discrete steps called ticks Typically you want the view to update once per tick between ticks That s the default behavior with tick based updates If you want additional view updates you can force an update using the display command The update may be skipped if the user is fast forwarding the model using the speed slider You don t have to use the tick counter to use tick based updates If the tick counter never advances the view will update only when you use the display command If you move the speed slider to a faster setting NetLogo will skip some of the updates that would ordinarily have happened Moving the speed slider to a slower setting doesn t cause additional updates rather it makes NetLogo pause after each update The slower the setting the longer the pause Even under tick based updates the view also updates whenever a button in the interface pops up both once and f
326. ool used to collect data from multiple runs of a model System Dynamics Modeler e Web Models can be saved as applets to be embedded in web pages note some features are not available from applets such as some extensions and the 3D view What is NetLogo Copyright Information Copyright 1999 2007 by Uri Wilensky All rights reserved The NetLogo software models and documentation are distributed free of charge for use by the public to explore and construct models Permission to copy or modify the NetLogo software models and documentation for educational and research purposes only and without fee is hereby granted provided that this copyright notice and the original author s name appears on all copies and supporting documentation For any other uses of this software in original or modified form including but not limited to distribution in whole or in part specific prior permission must be obtained from Uri Wilensky The software models and documentation shall not be used rewritten or adapted as the basis of a commercial software or hardware product without first obtaining appropriate licenses from Uri Wilensky We make no representations about the suitability of this software for any purpose It is provided as is without express or implied warranty To reference this software in academic publications please use Wilensky U 1999 NetLogo http ccl northwestern edu netlogo Center for Connected Learning and Computer Based Mod
327. oose a location for the origin of the world either Center Corner Edge or Custom By default the world has a center configuration where 0 0 is at the center of the world and the user defines the number of patches from the center to the right and left boundaries and the number of patches from the center to the top and bottom boundaries For Example If you set Max Pxcor 10 Min Pxcor will automatically be set to 10 thus there are 10 patches to the left of the origin and 10 patches to the right of patch 0 0 Interface Guide 75 NetLogo 4 0 User Manual A Corner configuration allows the user to define the location of the origin as one of the corners of the world upper left upper right lower left or lower right Then you define the far boundary in the x and y directions For example if you choose to put the origin in the lower left corner of the world you define the right and top positive boundaries Edge mode allows you to place the origin along one of the edges x or y then define the far boundary in that direction and both boundaries in the other For example if you select edge mode along the bottom of the world you must also define the top boundary as well as the left and the right Finally Custom mode allows the user to place the origin at any location in the world though patch O O must still exist in the world As you change the settings you will notice that the changes you make are reflected in the preview on the right
328. option to assign an action key This makes that key on the keyboard behave just like a button press If the button is a forever button it will stay down until the key is pressed again or the button is clicked Action keys are particularly useful for games or any model where rapid triggering of buttons is needed Buttons take turns More than one button can be pressed at a time If this happens the buttons take turns which means that only one button runs at a time Each button runs its code all the way through once while the other buttons wait then the next button gets its turn In the following examples setup is a once button and go is a forever button Example 1 The user presses setup then presses go immediately before the setup has popped back up Result setup finishes before go starts Example 2 While the go button is down the user presses setup Result the go button finishes its current iteration Then the setup button runs Then go starts running again Example 3 The user has two forever buttons down at the same time Result first one button runs its code all the way through then the other runs its code all the way through and so on alternating Note that if one button gets stuck in an infinite loop then no other buttons will run Turtle patch and link forever buttons There is a subtle difference between putting commands in a turtle patch or link forever button and putting the same co
329. or message saying NetLogo canttifind server dll a dat atadas 222 Arribas 222 tried to run one of the applets on your site but it didn t work What should do 222 Can make my model available as an applet while keeping the code secret 222 Can a model saved as an applet use import world file open and other commands that read files rrenan no nana no nono nc nn non nananono 222 When running my model as an applet get the following error java lang OutOfMemoryError Java heap Space cccccccnonoooonncnnnnccononnnnnnonnnnncnnnnnnnnns 223 When tried loading my model as an applet get an error like java lang ClassFormatError Incompatible magic Value ccccccccnnonococoncnoncccnanannns 223 RUANO A Doa 223 Can run NetLogo from a CD nasales 223 Why is NetLogo so much slower when unplug my Windows laptop 223 How come NetLogo won t start up on my Linux MachideP oooooooocccnncccccnoncconnnnnnnnccnananons 224 Can run NetLogo from the command line without the GUI eesesesteeeeeeees 224 Does NetLogo take advantage of multiple processors cores T cooccccccnonococoncnnncccnananono 224 Can distribute NetLogo model runs across a cluster of computers 224 l want to try HuBNeL Can A unas sn pa a bob 225 USADO ira AA A aaa ara a a Da dd 225 When move the speed slider all the way to the right why does my model seem to SIOPS a dora a ca tates A
330. or reporters Number input boxes read any type of constant number expression which allows a more open way to express numbers than a slider Color input boxes offer a NetLogo color chooser to the user ES Monitor Monitors display the value of any expression The expression could be a variable a complex expression or a call to a reporter Monitors automatically Interface Guide 73 NetLogo 4 0 User Manual update several times per second ate Plot Plots are real time graphs of data the model is generating ES Output The output area is a scrolling area of text which can be used to create a log of activity in the model A model may only have one output area ox Note Notes lets you add informative text labels to the Interface tab The contents of notes do not change as the model runs The other controls in the Interface Toolbar allow you to control the view updates and various other model properties M view updates Settings continuous normal speed e The slider lets you control how fast the model runs this is valuable since some models run so fast that it s hard to see what s going on You can also fast forward the model by moving the slider to the left and slowing down the frequency of view updates e The view updates check box controls whether view updates happen at all e The update mode menu allows you to switch between continuous and tick based update modes e The Settings button a
331. ore recent kernel versions We assume the problem is Linux specific and does not happen on other Unix based systems We are not sure if the problem ever occurs in practice during actual NetLogo model runs or only occurs in the context of our testing regimen The bug in the Sun s Java VM and not in NetLogo itself We hope that only the exp reporter is affected but we can t be entirely certain of this NetLogo users are encouraged to visit http developer java sun com developer bugParade bugs 5023712 html free registration required and vote for Sun to fix this bug e If NetLogo cannot find the font Lucida menus will be illegible This has been known to happen on Fedora Core 3 after upgrading packages Restarting the X Font Server xfs has resolved the problem in all reported cases e Sun s 1 5 0 Java runtime has display problems with GTK 2 0 and NetLogo Issues may include windows not updating properly interface elements being strangely sized menus being cut off at the bottom and weird characters appearing on the view To avoid these issues upgrade to Java 1 6 Known issues with computer HubNet See the_HubNet Guide for a list of known issues with computer HubNet 20 Known Issues Contacting Us Feedback from users is very valuable to us in designing and improving NetLogo We d like to hear from you Web Site Our web site at_ccl northwestern edu includes our mailing address and phone number It also has information about our
332. orever buttons and when a command entered in the Command Center finishes So it s not necessary to add the display command to once buttons that don t advance the tick counter Many forever buttons that don t advance the tick counter do need to use the display command An example in the Models Library is the Life model under Computer Science gt Cellular Programming Guide 111 NetLogo 4 0 User Manual Automata The forever buttons that let the user draw in the view use the display command so the user can see what they are drawing even though the tick counter is not advancing Choosing a mode Advantages of tick based updates over continuous updates include 1 Consistent predictable view update behavior which does not vary from computer to computer or from run to run 2 Continuous updates can confuse the user of your model by letting them see model states they aren t supposed to see which may be misleading 3 Increased speed Updating the view takes time so if one update per tick is enough then enforcing than there is only one update per tick will make your model faster 4 Since setup buttons don t advance the tick counter they are unaffected by the speed slider this is normally the desired behavior As mentioned above most models in our Models Library now uses tick based updates Continuous updates are useful for models in which execution is not divided into short discrete phases An example in the Models Library is Termite
333. ors that can be used too Here s a chart that shows the whole NetLogo color space black 0 white 9 9 gray 5 8 9 9 9 red 15 18 19 19 9 orange 25 20 21 22 28 29 29 9 brown 35 30 31 32 nm 38 39 39 9 yellow 45 40 41 42 48 49 49 9 green 55 50 51 52 58 59 59 9 lime 65 60 61 62 68 69 69 9 turquoise 75 70 TINA 78 79 79 9 cyan 85 80 81 82 87 88 89 89 9 sky 95 90 91 92 98 99 99 9 blue 105 100 101 102 107 108 109 109 9 violet 115 110 111 112 mais 119 119 9 magenta 125 120 121 122 k 128 129 129 9 pink 135 130 131 132 137 138 139 139 9 To get a color that doesn t have its own name you just refer to it by a number instead or by adding or subtracting a number from a name For example when you type set color red this does the same thing as ifyou had typed set color 15 And you can get a lighter or darker version of the same color by using a number that is a little larger or a little smaller as follows Tutorial 2 Commands 41 NetLogo 4 0 User Manual e Choose patches from the popup menu in the Command Center or use the tab key e Type set pcolor red 2 The spacing around the is important By subtracting from red you make it darker eType set pcolor red 2 By adding to red you make it lighter You can use this technique on any of the colors listed in the chart Agent Monitors and Agent Commanders In the previous activity we used the set command to change the colors of all the cars
334. ot pen interval with the point plotted as the upper or lower if you are plotting a negative number left corner of the bar e 2 point mode the plot pen draws a point at the point plotted Points are not connected The default mode for new pens is 0 line mode set plot x range set plot y range set plot x range min max set plot y range min max Sets the minimum and maximum values of the x or y axis of the current plot The change is temporary and is not saved with the model When the plot is cleared the ranges will revert to their default values as set in the plot s Edit dialog setxy NetLogo Dictionary 323 NetLogo 4 0 User Manual setxy xy The turtle sets its x coordinate to x and its y coordinate to y Equivalent to set xcor x set ycor y except it happens in one time step instead of two If x or yis outside the world NetLogo will throw a runtime error setxy 0 0 7 turtle moves to the middle of the center patch setxy random xcor random ycor 7 turtle moves to a random point setxy random pxcor random pycor 7 turtle moves to the center of a random patch See also move to shade of shade of color color2 Reports true if both colors are shades of one another false otherwise show shade of blue red gt false show shade of blue blue 1 gt true show shade of gray white gt true shape shape P This is a built in turtle and link variable It holds a string that is the n
335. ou ll at least get a table of partial results After selecting your output formats BehaviorSpace will prompt you for the name of a file to save the results to The default name ends in csv You can change it to any name you want but don t leave off the csv part that indicates the file is a Comma Separated Values CSV file This is a plain text data format that is readable by any text editor as well as by most popular spreadsheet and database programs A dialog will appear titled Running Experiment In this dialog you ll see a progress report of how many runs have been completed so far and how much time has passed If you entered any reporters for measuring the runs and if you left the Measure runs at every step box checked then you ll see a plot of how they vary over the course of each run You can also watch the runs in the main NetLogo window If the Running Experiment dialog is in the way just move it to a different place on the screen The view and plots will update as the model runs If you don t need to see them update then use the checkboxes in the Running Experiment dialog to turn the updating off This will make the experiment go faster If you want to stop your experiment before it s finished press the Abort button But note that you ll lose any results that were generated in the spreadsheet format up to that point Table results are written as the experiment runs and will not be lost When all the runs have f
336. ou must include the above copyright notice and this license and disclaimer in the documentation and or other materials provided with the distribution and must indicate the use of this software in a prominent publically accessible location of the larger work You must not use the Authors s names to endorse or promote products derived from this software without the specific prior written permission of the Authors THE SOFTWARE IS PROVIDED AS IS WITHOUT WARRANTY OF ANY KIND EXPRESS OR IMPLIED INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS NOR THEIR EMPLOYERS NOR GEORGE MASON UNIVERSITY BE LIABLE FOR ANY CLAIM DAMAGES OR OTHER LIABILITY WHETHER IN AN ACTION OF CONTRACT TORT OR OTHERWISE ARISING FROM OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE JpeglmagesToMovie For movie making NetLogo uses code adapted from JpeglmagesToMovie java by Sun Microsystems The copyright for that code is as follows Copyright c 1999 2001 Sun Microsystems Inc All Rights Reserved Sun grants you Licensee a non exclusive royalty free license to use modify and redistribute this software in source and binary code form provided that i this copyright notice and license appear on all copies of the software and ii Licensee does not utilize the software in a manner which is disparaging to
337. ow is the NetLogo language different from the StarLogo and StarLogoT languages How do convert my StarLogo or StarLogoT model to NetLogo We don t have a document that specifically summarizes the differences between these programs If you have built models in StarLogo or StarLogoT before then we suggest reading the Programming Guide section of this manual to learn about NetLogo particularly the sections on Ask and Agentsets Looking at some of the sample models and code examples in the Models Library may help as well If you need any help converting your StarLogo or StarLogoT model to NetLogo please feel free to seek help on the NetLogo Users Group You may also ask us for help at feedback ccl northwestern edu How does the NetLogo language differ from other Logos There is no standard definition of Logo it is a loose family of languages We believe that NetLogo shares enough syntax vocabulary and features with other Logos to earn the Logo name Still NetLogo differs in some respects from most other Logos The most important differences are as follows Surface differences e The precedence of mathematical operators is different Infix math operators like etc have lower precedence than reporters with names For example in many Logos if you write sin x 1 it will be interpreted as sin x 1 NetLogo on the other hand interprets it the way most other programming languages would and the way the same expression woul
338. ow rudimentary support in the API for extensions to define new data types the array and table extensions are examples the random number generator is now accessible by extensions sample extensions are now installed with Java source code included formerly it was separate downloads Version 3 1 4 February 2007 e installer supports Windows Vista e rewritten and expanded Tutorial 3 e new sound extension command play note later for playing musical phrases e extensions not requiring additional jars work in saved applets e bugfixes e What s New 13 NetLogo 4 0 User Manual Version 3 1 April 2006 e topologies wrapping at world edges now optional e automatically randomized ordering of agentsets e you now specify the singular form of a breed name as well as the plural e sort and sort by work on agentsets now e link primitives for network and geometry models experimental e tieand untie primitives experimental Version 3 0 September 2005 e 3D view for 2D models e System Dynamics Modeler e follow ride and watch commands for tracking particular agents e drawing layer for marks left by turtles e more attractive colors e more attractive Information tab e GoGo extension for interfacing NetLogo with physical devices e Color Swatches dialog helps you choose colors e image file importing e buttons take turns now instead of interleaving their code with each other Version 2 1 December 2004 e headle
339. p homepage mac com sroy mrjadapter Quaqua NetLogo uses the Quaqua Look and Feel library which is Copyright c 2003 2005 Werner Randelshofer _http www randelshofer ch werner randelshofer bluewin ch All Rights Reserved The library is covered by the GNU LGPL Lesser General Public License The text of that license is included in the docs folder which accompanies the NetLogo download and is also available from htto www gnu org copyleft lesser html JHotDraw For the system dynamics modeler NetLogo uses the JHotDraw library which is Copyright c 1996 1997 by IFA Informatik and Erich Gamma The library is covered by the GNU LGPL Lesser General Public License The text of that license is included in the docs folder which accompanies the NetLogo download and is also available from_http www gnu org copyleft lesser html MovieEncoder For movie making NetLogo uses code adapted from sim util media MovieEncoder java by Sean Luke distributed under the MASON Open Source License The copyright for that code is as follows This software is Copyright 2003 by Sean Luke Portions Copyright 2003 by Gabriel Catalin Balan Liviu Panait Sean Paus and Dan Kuebrich All Rights Reserved 4 Copyright Information NetLogo 4 0 User Manual Developed in Conjunction with the George Mason University Center for Social Complexity By using the source code binary code files or related data included in this distribution you agree to
340. patch command The reason is that it acts on all the patches at once patch commands act on individual patches diffuse chemical 0 5 7 each patch diffuses 50 of its variable 7 chemical to its neighboring 8 patches Thus each patch gets 1 8 of 50 of the chemical from each neighboring patch NetLogo Dictionary 253 NetLogo 4 0 User Manual diffuse4 diffuse4 patch variable number ig Like diffuse but only diffuses to the four neighboring patches to the north south east and west not to the diagonal neighbors diffuse4 chemical 0 5 7 each patch diffuses 50 of its variable 7 Chemical to its neighboring 4 patches Thus 77 each patch gets 1 4 of 50 of the chemical 7 from each neighboring patch directed link breed directed link breed lt link breeds gt lt link breed gt This keyword like the globals and breeds keywords can only be used at the beginning of the Procedures tab before any procedure definitions It defines a directed link breed Links of a particular breed are always all directed or all undirected The first input defines the name of the agentset associated with the link breed The second input defines the name of a single member of the breed Directed links can be created using create link s to and create link s from but not create link s with Any link of the given link breed e is part of the agentset named by the link breed name e has its built in variable breed set to that a
341. patch size to 20 and press OK What happened to the size of the view Did its shape change Editing the view also lets you change other settings including the font size of labels and whether the view uses shapes Feel free to experiment with these and other settings as well Tutorial 1 Models 35 NetLogo 4 0 User Manual Once you are done exploring the Wolf Sheep Predation model you may want to take some time just to explore some of the other models available in the Models Library The Models Library The library contains five sections Sample Models Perspective Demos Curricular Models Code Examples and HubNet Computer Activities Sample Models The Sample Models section is organized by subject area and currently contains more than 210 models We are continuously working on adding new models to it so come visit this section at a later date to view the new additions to the library Some of the folders in Sample Models have folders inside them labeled unverified These models are complete and functional but are still in the process of being reviewed for content accuracy and quality of code Perspective Demos These models are all models that are also in Sample Models however they are slightly modified to demonstrate NetLogo s perspective features Curricular Models These are models designed to be used in schools in the context of curricula developed by the CCL at Northwestern University Some of these are models
342. pdates sent to the clients If you would like to have more control over the view updates you can use hubnet broadcast view and hubnet send view to explicitly send the view either to all the clients or particular clients respectively However you should note that view mirroring only updates the information that has changed since the last update whereas send and broadcast view send all of the world information every time That means that the messages could be bigger a lot bigger and therefore slower to update HubNet Authoring Guide 173 NetLogo 4 0 User Manual If there is no View in the clients or if the Mirror 2D View on Clients checkbox in the HubNet Control Center is not checked then no view messages are sent to the clients NOTE Since hubnet broadcast view and hubnet send view are experimental primitives the behavior may change in a future release Note Some of the View features in NetLogo are not yet implemented on the HubNet clients such as View Wrapping and Observer Perspectives Clicking in the View on Clients If the View is included in the client a message is sent to the server every time the user clicks in the view The tag of the message is View and the message consists of a two item list of the x and y coordinates For example to turn any patch that was clicked on by the client red you would use the following NetLogo code if hubnet message tag View ask patches with pxcor pycor set pcolor red
343. pe of the one below though your plot might not look exactly the same Remember that we left Autoplot on This allows the plot to readjust itself when it runs out of room If you forget which pen is which click on the Pens label on the top right corner of the plot You might try running the model several times to see what aspects of the plot are the same and which are different Tutorial 3 Procedures 63 NetLogo 4 0 User Manual Tick counter To make comparisons between plots from one model run and another it is often useful to do the comparison for the same length of model run Learning how to stop or start an action at a specific time can help make this happen by stopping the model at the same point each model run Keeping track of how many times the go procedure is run is a useful way to cue these actions To keep track of this we will use NetLogo s built in tick counter e Change the go procedure ES 90 ae aci gt gt 200 Seo 1 move turtles eart grass reproduce check death regrow grass trek do plots end e Now setup and run the model The graph and model won t keep running forever They should stop automatically when the tick counter in the Interface tab s toolbar reaches 500 The tick command advances the tick counter by 1 ticks is a reporter which reports the current value of the tick counter clear a11 takes care of resetting the tick counter to O when a new run starts Note that we put tick
344. peat 3 beep wait 0 1 produces 3 beeps in succession separated by 1 10th of a second both ends both ends Reports the agentset of the 2 nodes connected by this link Gre 2 ask turtle O create link with turtle 1 ask link 01 ask both ends set color red turtles 0 and 1 both turn red breed breed MS 244 NetLogo Dictionary NetLogo 4 0 User Manual This is a built in turtle and link variable It holds the agentset of all turtles or links of the same breed as this turtle or link For turtles or links that do not have any particular breed this is the turtles agentset of all turtles or the links agentset of all links respectively You can set this variable to change a turtle or link s breed See also breed directed link breed undirected link breed Example breed cats cat breed dogs dog turtle code if breed cats show meow set breed dogs show woof directed link breed roads road link code if breed roads set color gray breed breed lt breeds gt lt breed gt This keyword like the globals turtles own and patches own keywords can only be used at the beginning of the Procedures tab before any procedure definitions It defines a breed The first input defines the name of the agentset associated with the breed The second input defines the name of a single member of the breed Any turtle of the given breed e is part of the agentset named by the
345. pecify a different encoding than us ascii such as UTF 8 but NetLogo doesn t support non ASCII characters in most situations so specifying a different encoding may be pointless Controlling API If BehaviorSpace is not sufficient for your needs a possible alternative is to use our Controlling API which lets you write Java code that controls NetLogo The API lets you run BehaviorSpace experiments from Java code or you can write custom code that controls NetLogo more directly to do BehaviorSpace like things See the Controlling section of the User Manual for further details on both possibilities 160 BehaviorSpace Guide NetLogo 4 0 User Manual Conclusion BehaviorSpace is still under development We d like to hear from you about what what additional features would be useful to you in your work Please write us at feedback ccl northwestern edu BehaviorSpace Guide 161 NetLogo 4 0 User Manual 162 BehaviorSpace Guide HubNet Guide This section of the User Manual introduces the HubNet system and includes instructions to set up and run a HubNet activity HubNet is a technology that lets you use NetLogo to run participatory simulations in the classroom In a participatory simulation a whole class takes part in enacting the behavior of a system as each student controls a part of the system by using an individual device such as a networked computer or Texas Instruments graphing calculator For example in the Gridlock simulation eac
346. ples section of the Models Library e Agents e Procedures e Variables e Colors e Ask e Agentsets e Breeds e Buttons e Lists e Math e Random Numbers e Turtle Shapes e Link Shapes e Tick Counter e View Updates e Plotting e Strings e Output e File I O e Movies e Perspective e Drawing e Topology e Links e Ask Concurrent e Tie e Syntax Agents The NetLogo world is made up of agents Agents are beings that can follow instructions Each agent can carry out its own activity all simultaneously In NetLogo there are four types of agents turtles patches links and the observer Turtles are agents that move around in the world The world is two dimensional and is divided up into a grid of patches Each patch is a square piece of ground over which turtles can move Links are agents that connect two turtles The observer doesn t have a location you can imagine it as looking out over the world of turtles and patches When NetLogo starts up there are no turtles yet The observer can make new turtles Patches can make new turtles too Patches can t move but otherwise they re just as alive as turtles and the observer are Programming Guide 87 NetLogo 4 0 User Manual Patches have coordinates The patch at coordinates 0 0 is called the origin and the coordinates of the other patches are the horizontal and vertical distances from this one We call the patch s coordinates pxcor and p
347. plot Note that later if you change the name of the plot you ll also have to update the set current plot calls in your model to use the new name Copy and paste can be helpful here 112 Programming Guide NetLogo 4 0 User Manual Specifying a pen When you make a new plot it just has one pen in it If the current plot only has one plot pen then you can start plotting to it right away But you can also have multiple pens in a plot You can create additional pens by editing the plot and using the controls in the Plot Pens section at the bottom of the edit dialog Each pen should have a unique name You ll be using its name to refer to it in your code in the Procedures tab For a plot with multiple pens you have to specify which pen you want to plot with If you don t specify a pen plotting will take place with the first pen in the plot To plot with a different pen use the set current plot pen command with the name of the pen enclosed in double quotes like this set current plot pen distance Plotting points The two basic commands for actually plotting things are plot and plotxy With plot you need only specify the y value you want plotted The x value will automatically be 0 for the first point you plot 1 for the second and so on That s if the plot pen s interval is the default value of 1 you can change the interval The plot command is especially handy when you want your model to plot a new point at every time st
348. point Results between 0 and 0 5 get rounded to 0 but results between 0 5 and 1 5 get rounded to 1 the latter range is twice as large If you want 0 0 1 0 2 0 9 and 1 to all be equally likely an alternative is to write random 11 10 this gives all 11 answers with equal probability How can I keep two turtles from occupying the same patch See One Turtle Per Patch Example in the Code Examples section of the Models Library How can find out if a turtle is dead When a turtle dies it turns into nobody nobody is a special value used in NetLogo used to indicate the absence of a turtle or patch So for example if turtle O nobody You could also use is turtle Lf TIs turtle turtle 0 ss Does NetLogo have arrays In the current version of NetLogo lists are true linked lists rather than having an array based underlying implementation as in earlier NetLogo versions True arrays are available by using the array extension See the Arrays amp Tables section of the User Manual 232 FAQ Frequently Asked Questions NetLogo 4 0 User Manual Does NetLogo have hash tables or associative arrays Yes using the table extension See the Arrays amp Tables section of the User Manual How can use different patch neighborhoods circular Von Neumann Moore etc The in radius primitives lets you access circular neighborhoods of any radius The neighbors primitive gives you a Moore neighborhood of radiu
349. pycor There is a complete list here You can also define your own variables You can make a global variable by adding a switch or a slider to your model or by using the globals keyword at the beginning of your code like this globals score You can also define new turtle patch and link variables using the turtles own patches own and links own keywords like this turtles own energy speed patches own friction links own strength These variables can then be used freely in your model Use the set command to set them If you don t set them they ll start out storing a value of zero Global variables can be read and set at any time by any agent As well a turtle can read and set patch variables of the patch it is standing on For example this code ask turtles set pcolor red causes every turtle to make the patch it is standing on red Because patch variables are shared by turtles in this way you can t have a turtle variable and a patch variable with the same name In other situations where you want an agent to read a different agent s variable you can use of Example 90 Programming Guide NetLogo 4 0 User Manual show color of turtle 5 7 prints current color of turtle with who number 5 You can also use of with a more complicated expression than just a variable name for example show xcor ycor of turtle 5 7 prints the sum of the x and y coordinates of turtle with who number 5 Local var
350. r which allows you to issue NetLogo commands Working with Interface Elements The toolbar on the Interface tab contains buttons that let you edit delete and create items in the Interface tab and a menu that lets you select different interface items such as buttons and sliders B ron it te Add abe Button SEE Slider 18 Switch E Chooser Input 5 Monitor Plot ES Output a Note The buttons in the toolbar are described below Adding To add an interface element select the element from the the drop down menu Note that the Add button becomes pressed Then click on the white area below the toolbar If the menu is already showing the right type you can just press the Add button instead of using the menu again Selecting To select an interface element drag a rectangle around it with your mouse A gray border will appear around the element to indicate that it is selected Selecting Multiple Items You can select multiple interface elements at the same time by including them in the rectangle you drag If multiple elements are selected one of them is the key item which means that if you use the Edit or Delete buttons on the Interface Toolbar only the key item is affected The key item is indicated by a darker gray border than the other items Unselecting To unselect all interface elements click the mouse on the white background of the Interface tab To unselect an individual element control click Maci
351. r in the range 0 to 140 not including 140 itself that represents the given color specified in the HSB spectrum in NetLogo s color space All three values should be in the range 0 to 255 The color reported may be only an approximation since the NetLogo color space does not include all possible colors It contains only certain discrete hues and for each hue either saturation or brightness may vary but not both at least one of the two is always 255 show approximate hsb 0 0 0 gt 0 black show approximate hsb 0 5 1 0 1 0 gt 85 cyan See also_extract hsb approximate rgb extract rgb approximate rgb approximate rgb red green blue Reports a number in the range 0 to 140 not including 140 itself that represents the given color specified in the RGB spectrum in NetLogo s color space All three inputs should be in the range 0 to 255 The color reported may be only an approximation since the NetLogo color space does not include all possible colors See_approximate hsb for a description of what parts of the HSB color space NetLogo colors cover this is difficult to characterize in RGB terms 240 NetLogo Dictionary NetLogo 4 0 User Manual show approximate rgb 0 0 0 gt 0 black show approximate rgb 0 11 gt 85 cyan See also extract rgb approximate hsb and_extract hsb Arithmetic Operators 4 lt gt ls lt gt All of these operators take two inputs and
352. r interface NetLogo is written in Java so it can run on all major platforms Mac Windows Linux et al It is run as a standalone application Models can be run as Java applets inside a web browser Features You can use the list below to help familiarize yourself with the features NetLogo has to offer e System Cross platform runs on Mac Windows Linux et al e Language 4 Fully programmable Simple language structure Language is Logo dialect extended to support agents Mobile agents turtles move over a grid of stationary agents patches Create links between turtles to make aggregates networks and graphs Large vocabulary of built in language primitives Double precision floating point math IEEE 754 Runs are exactly reproducible cross platform e Environment What is NetLogo 1 NetLogo 4 0 User Manual View your model in either 2D and 3D Scalable and rotatable vector shapes 4 Turtle and patch labels Command center for on the fly interaction 4 Interface builder w buttons sliders switches choosers monitors text boxes notes output area Speed slider lets you fast forward your model or see it in slow motion Powerful and flexible plotting system 4 Info tab for annotating your model HubNet participatory simulations using networked devices Agent monitors for inspecting and controlling agents Export and import functions export data save and restore state of model make a movie BehaviorSpace t
353. r more Center information Zoom AA the overall screen size of the model Useful on large monitors or when using a projector in front of a group Normal Size Resetthe screen size of the model to the normal size Smaller Decrease the overall screen size of the model abs This menu offers keyboard shortcuts for each of the tabs On Macs it s Command 1 through Command 3 On Windows it s Control 1 through Control 3 Help Macs this menu item is on the NetLogo menu instead Dictionar reporter Manual NetLogo Dictionary Opens the NetLogo Dictionary in a web browser Tabs At the top of NetLogo s main window are three tabs labeled Interface Information and Procedures Only one tab at a time can be visible but you can switch between them by clicking on the tabs at the top of the window Interface 2 Information Procedures F e view updates r u abc Button w y Settings l Continuous ry S Edit Delete Add normal speed Interface Guide 71 NetLogo 4 0 User Manual Right below the row of tabs is a toolbar containing a row of buttons The buttons available vary from tab to tab Interface Tab The Interface tab is where you watch your model run It also has tools you can use to inspect and alter what s going on inside the model When you first open NetLogo the Interface tab is empty except for the View where the turtles and patches appear and the Command Cente
354. r to the current item of each list Some examples make this clearer foreach 1 2 3 2 4 6 show word the sum is 1 2 gt the sum is 3 gt the sum is 6 gt the sum is 9 foreach list turtle 1 turtle 2 3 4 ask 1 fd 2 7 turtle 1 moves forward 3 patches 7 turtle 2 moves forward 4 patches See also_map _ forward fd forward number The turtle moves forward by number steps one step at a time If number is negative the turtle moves backward fd 10 is equivalent to repeat 10 jump 1 fd 10 5 is equivalentto repeat 10 jump 1 jump 0 5 If the turtle cannot move forward number steps because it is not permitted by the current topology the turtle will complete as many steps of 1 as it can then stop See also jump can move fput fput item list Adds item to the beginning of a list and reports the new list NetLogo Dictionary 267 NetLogo 4 0 User Manual 7 suppose mylist is 5 7 10 set mylist fput 2 mylist 7 mylist is now 2 5 7 10 G globals globals var7 This keyword like the breed lt breeds gt own patches own and turtles own keywords can only be used at the beginning of a program before any function definitions It defines new global variables Global variables are global because they are accessible by all agents and can be used anywhere in a model Most often globals is used to define variables or constants that need to be use
355. r with the following contents Required e A JAR file with the same name as the extension the following contents one or more classes that implementation org nlogo api Primitive a main class that implements org nlogo api ClassManager and a NetLogo extension manifest file with the following four tags 0 Manifest Version always 1 0 0 Extension Name the name of the extension 0 Class Manager the fully qualified name of a class implementing org nlogo api ClassManager 0 Net Logo Extension API Version the version of NetLogo Extension API for which this JAR is intended If a user opens the extension with NetLogo that has a different Extension API version a warning message is issued To tell which version of the Extension API your NetLogo supports choose the About NetLogo item in the Help menu and then click on the System tab Or you can launch NetLogo jar with the extension api version argument Optional e One or more NetLogo models demonstrating how the extension is used e One or more JAR files which the extension requires e A lib directory with any required native libraries e A src directory containing the source code for the model e Documentation To build your extension you must include NetLogo jar in your class path Examples Several sample extensions with full Java source code are included with NetLogo Some others are available for download here 188 Extensions Guide NetLogo 4 0 User Manual
356. random point in the world The second command puts the turtle on the center of a random patch An even more concise way to put a turtle on the center of a random patch is move to one of patches How do take the negative of a number Any of these ways x 1 x OD x With the first way the parentheses are required My turtle moved forward 1 but it s still on the same patch Why Moving forward 1 is only guaranteed to take a turtle to a new patch if the turtle s heading is a multiple of 90 that is exactly north south east or west It s because the turtle might not be standing in the center of a patch It might be near a corner For example suppose your turtle is close to the southwest corner of a patch and is facing northeast The length of the patch diagonal is 1 414 the square root of two so fd 1 will leave the turtle near the northeast corner of the same patch If you don t want to have to think about these issues one possibility is to write your model in such a way that your turtles always come to rest on patch centers See next question 230 FAQ Frequently Asked Questions NetLogo 4 0 User Manual How do keep my turtles on patch centers A turtle is on a patch center when its xcor and ycor are integers You can move a turtle to the center of its current patch with either of these two equivalent commands move to patch here setxy pxcor pycor But you ll never need to do that if you never allow turt
357. re so the error message will go away e Switch to the Procedures tab e Type the following EO Setup clear all create turtles 100 ask turtles setxy random xcor random ycor end When you re done the Procedures tab looks like this O 06 NetLogo Untitled Interface Information Procedures 2 Y Procedures w Find Check to setup clear all create turtles 100 ask turtles setxy random xcor random ycor 7 end Note that the lines are indented different amounts Most people find it helpful to indent their code like this but it is not mandatory It makes the code easier to read and change Your procedure began with the word to and ended with the word end Every new procedure you create will begin and end with these two words Let s look at what you typed in and see what each line of your procedure does eto setup begins defining a procedure named setup 48 Tutorial 3 Procedures NetLogo 4 0 User Manual e clear al1 resets the world to an initial empty state All the patches turn black and any turtles you might have created disappear Basically it wipes the slate clean for a new model run ecreate turtles 100 creates 100 turtles They start out standing at the origin that is the center of patch 0 0 eask turtles tells each turtle to run independently the commands inside the brackets Every command in NetLogo is run by some agent ask is a command too Here the observer
358. re exits through use of the stop command or the report command Note In most circumstances you should use a forever button in order to repeat something forever The advantage of using a forever button is that the user can click the button to stop the loop Iput Iput value list Adds value to the end of a list and reports the new list 7 suppose mylist is 2 7 10 Bob set mylist lput 42 mylist 7 mylist now is 2 7 10 Bob 42 map map reporter list map reporter list With a single list the given reporter is run for each item in the list and a list of the results is collected and reported In reporter use to refer to the current item of list show map round 1 1 2 2 2 7 gt 1 2 3 show map 1 2 3 gt 1 4 9 With multiple lists the given reporter is run for each group of items from each list So it is run once for the first items once for the second items and so on All the lists must be the same length In reporter use 1 through n to refer to the current item of each list Some examples make this clearer show map 1 2 1 2 3 2 4 6 gt 3 6 9 show map 1 2 3 1 2 3 2 4 6 3 5 9 gt true false true 288 NetLogo Dictionary NetLogo 4 0 User Manual See also foreach max max list Reports the maximum number value in the list It ignores other types of items show max xcor of turtles 7 prints the x coordinate of the turtle whic
359. re than halfway to the left the model will be running so slowly that you can watch turtles moving one at a time This is new in NetLogo 4 0 in previous NetLogo versions no matter how slowly you ran a model you would never see the agents in an ask moving one at a time all the agents in an ask always appeared to move together 140 Transition Guide NetLogo 4 0 User Manual Numbers NetLogo no longer maintains an internal distinction between integers and floating point numbers So for example Old observer gt print 3 3 observer gt print 3 0 3 0 observer gt print 1 2 3 observer gt print 1 5 1 5 30 observer gt print 3 true ll w o The last line shows that although the distinction between integer 3 and floating point 3 0 was maintained the two numbers were still considered equal New observer gt print 3 3 observer gt print 3 0 3 observer gt print 1 2 3 observer gt print 1 5 1 5 3 observer gt print 3 true ll w o We expect that only rare models will be negatively impacted by this change A benefit of this change is that NetLogo now supports a much larger range of integers The old range was 2 147 483 648 to 2 147 483 647 around 2 billion the new range is 9 007 199 254 740 992 around 9 quadrillion Agentset building NetLogo 3 1 and some earlier versions included primitives called turtles from and patches from that were occasionally useful for building agentsets
360. reeds using the breed keyword at the top of the Procedures tab before any procedures breed wolves wolf breed sheep a sheep You can refer to a member of the breed using the singular form just like the turtle reporter When printed members of the breed will be labeled with the singular name Some commands and reporters have the plural name of the breed in them such as create lt breeds gt Others have the singular name of the breed in them such as_ lt breed gt The order in which breeds are declared is also the order order in which they are layered in the view So breeds defined later will appear on top of breeds defined earlier in this example sheep will be Programming Guide 97 NetLogo 4 0 User Manual drawn over wolves When you define a breed such as sheep an agentset for that breed is automatically created so that all of the agentset capabilities described above are immediately available with the sheep agentset The following new primitives are also automatically available once you define a breed create sheep hatch sheep sprout sheep sheep here sheep at sheep on and is a sheep Also you can use sheep own to define new turtle variables that only turtles of the given breed have A turtle s breed agentset is stored in the breed turtle variable So you can test a turtle s breed like this if breed wolves Note also that turtles can change breeds A wolf doesn t have to remain a wo
361. remains in place set mylist 2 7 4 7 Bob 7 set mylist remove duplicates mylist 5 mylist is now 2 7 4 Bob remove item remove item index list remove item index string For a list reports a copy of list with the item at the given index removed For strings reports a copy of string2 with the character at the given index removed Note that the indices begin from 0 not 1 The first item is item 0 the second item is item 1 and so on set mylist 2 7 4 7 Bob set mylist remove item 2 mylist 7 mylist is now 2 7 7 Bob show remove item 2 string gt sting repeat repeat number commands Runs commands number times NetLogo Dictionary 315 NetLogo 4 0 User Manual pd repeat 36 fd 1 rt 10 the turtle draws a circle replace item replace item index list value replace item index string1 string2 On a list replaces an item in that list index is the index of the item to be replaced starting with 0 The 6th item in a list would have an index of 5 Note that replace item is used in conjunction with set to change a list Likewise for a string but the given character of string 1 removed and the contents of string2 spliced in instead show replace item 2 2 7 4 5 15 gt 2 7 15 5 show replace item 1 cat are gt caret report report value Immediately exits from the current to report procedure and reports value as the result of that procedure report and to report are al
362. reporter use to refer to the current item of list NetLogo Dictionary 265 NetLogo 4 0 User Manual show filter lt 3 1 3 2 gt 1 2 show filter first t hi there everyone gt hi everyone See also_map reduce _ first first list first string On a list reports the first Oth item in the list On a string reports a one character string containing only the first character of the original string floor floor number Reports the largest integer less than or equal to number show floor 4 5 gt 4 show floor 4 5 gt 5 follow follow turtle e Similar to ride but in the 3D view the observer s vantage point is behind and above turtle See also follow me ride reset perspective watch subject follow me follow me Asks the observer to follow the calling turtle See also follow foreach 266 NetLogo Dictionary NetLogo 4 0 User Manual foreach list commands foreach list1 commands With a single list runs commands for each item of list In commands use to refer to the current item of list foreach 1 1 2 2 2 6 show word gt round 2 gt 1 1 gt 1 gt 2 2 gt 2 gt 2 6 gt 3 With multiple lists runs commands for each group of items from each list So they are run once for the first items once for the second items and so on All the lists must be the same length In commands use_ 1 through_ n to refe
363. reset ticks tick tick advance ticks world width world height Perspective follow follow me reset perspective rp ride ride me subject watch watch me HubNet hubnet broadcast hubnet broadcast view hubnet enter message hubnet exit message hubnet fetch message hubnet message hubnet message source hubnet message tag hubnet message waiting hubnet reset hubnet send hubnet send view hubnet set client interface Input output beep clear output date and time export view export interface export output export plot export all plots export world import drawing import pcolors import pcolors rgb import world mouse down mouse inside mouse patch mouse xcor mouse ycor output print output show output type output write print read from string reset timer set current directory show timer type user directory user file user new file user input user message user one of user yes or no write file at end file close file close all file delete file exists file flush file open file print file read file read characters file read line file show file type file write user directory user file user new file List but first but last empty filter first foreach fput histogram is list item last length list Iput map member modes n of n values of position one of reduce remove remove duplicates remove item replace item reverse sentence shuffle sort sort by sublist 236 NetLogo Dictionary NetLogo 4 0 User Manual Operators lt
364. retrieved by hubnet fetch message For Calculator HubNet this will report one of the variable names set with the hubnet set client interface primitive For Computer HubNet this will report one of the Display Names of the interface elements in the client interface See the HubNet Authoring Guide for details hubnet message waiting hubnet message waiting This looks for a new message sent by the clients It reports true if there is one and false if there is not See the HubNet Authoring Guide for details hubnet reset hubnet reset Starts up the HubNet system HubNet must be started to use any of the other hubnet primitives with the exception of hubnet set client interface See the HubNet Authoring Guide for details 272 NetLogo Dictionary NetLogo 4 0 User Manual hubnet send hubnet send string tag name value hubnet send list of strings tag name value For Calculator HubNet this primitive acts in exactly the same manner as hubnet broadcast We plan to change this in a future version of NetLogo For Computer HubNet it acts as follows For a string this sends value from NetLogo to the tag tag name on the client that has string for its user name For a list of strings this sends value from NetLogo to the tag tag name on all the clients that have a user name that is in the list of strings Sending a message to a non existent client using hubnet send generates a hubnet exit message See the HubNet Aut
365. rints true ask turtle 1 show in link neighbor turtle O prints true show out link neighbor turtle 0 prints false in lt breed gt neighbors in link neighbors in lt breed gt neighbors in link neighbors Reports the agentset of all the turtles that have directed links coming from them to the caller ert 4 ask turtle 0 create links to other turtles NetLogo Dictionary 277 NetLogo 4 0 User Manual ask turtle 1 ask in link neighbors set color blue turtle 0 turns blue in lt breed gt from in link from in lt breed gt from turtle in link from turtle Report the link from turtle to the caller If no link exists then it reports nobody ert 2 ask turtle 0 create link to turtle 1 ask turtle 1 show in link from turtle 0 shows link 0 1 ask turtle 0 show in link from turtle 1 shows nobody includes __ includes filename Causes external NetLogo source files with the n1s suffix to be included in this model Included files may contain breed variable and procedure definitions __ includes can only be used once per file in radius agentset in radius number Reports an agentset that includes only those agents from the original agentset whose distance from the caller is less than or equal to number This can include the calling agent itself The distance to or a from a patch is measured from the center of the patch ask turtles ask patches in radius 3 s
366. rked computer with NetLogo installed for the activity leader and a networked computer with NetLogo installed for each participant We also suggest an attached projector for the leader to project the entire simulation to the participants Starting an activity You ll find the HubNet activities in NetLogo s Models Library in the HubNet Computer Activities folder We suggest doing a few practice runs of an activity before trying it in front of a class 00 Start HubNet Activity Session name B1101 Y Broadcast server location Open a Computer HubNet model NetLogo will prompt you to enter the name of your new HubNet session This is the name that participants will use to identify this activity Enter a name and press Start NetLogo will open the HubNet Control Center which lets you interact with the HubNet server You as the leader should then notify everyone that they may join To join the activity participants launch the HubNet Client application and enter their name They should see your activity listed and can join your activity by selecting it and pressing Enter If the activity you started is not listed the student can enter the server address manually which can be found in the HubNet Control Center 164 HubNet Guide NetLogo 4 0 User Manual HubNet Control Center 606 HubNet Control Center Name everreau Clients Activity Disease Server address 129 105 107 235 Port number 9173 Settings Mirror plots on cl
367. rmation 3 NetLogo 4 0 User Manual CONTRIBUTORS BE LIABLE FOR ANY DIRECT INDIRECT INCIDENTAL SPECIAL EXEMPLARY OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES LOSS OF USE DATA OR PROFITS OR BUSINESS INTERRUPTION HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY WHETHER IN CONTRACT STRICT LIABILITY OR TORT INCLUDING NEGLIGENCE OR OTHERWISE ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE Colt Parts of NetLogo specifically the random gamma primitive are based on code from the Colt library http hoschek home cern ch hoschek colt The copyright for that code is as follows Copyright 1999 CERN European Organization for Nuclear Research Permission to use copy modify distribute and sell this software and its documentation for any purpose is hereby granted without fee provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation CERN makes no representations about the suitability of this software for any purpose It is provided as is without expressed or implied warranty MRJ Adapter NetLogo uses the MRJ Adapter library which is Copyright c 2003 2005 Steve Roy lt sroy roydesign net gt The library is covered by the Artistic License http nomepage mac com sroy artisticlicense html MRJ Adapter is available from htt
368. rout without interruption Only the current procedure stops not all execution for the agent if not any turtles stop 328 NetLogo Dictionary NetLogo 4 0 User Manual 7 exits if there are no more turtles Note stop can be used to stop a forever button If the forever button directly calls a procedure then when that procedure stops the button stops In a turtle or patch forever button the button won t stop until every turtle or patch stops a single turtle or patch doesn t have the power to stop the whole button subject subject Reports the turtle or patch that the observer is currently watching following or riding Reports nobody if there is no such turtle or patch See also_watch follow ride sublist substring sublist list position position2 substring string position position2 Reports just a section of the given list or string ranging between the first position inclusive and the second position exclusive Note The positions are numbered beginning with 0 not with 1 show sublist 99 88 77 66 1 3 gt 88 77 show substring apartment 1 5 gt part subtract headings subtract headings heading1 heading2 Computes the difference between the given headings that is the number of degrees in the smallest angle by which heading2 could be rotated to produce heading1 A positive answer means a clockwise rotation a negative answer counterclockwise The result is always in the range 1
369. rtle monitor besides right clicking or control clicking depending on your operating system One way is to choose Turtle Monitor from the Tools menu then type the who number of the turtle you want to inspect into the who field and press return The other way isto type inspect turtle 0 or other who number into the Command Center You close a turtle monitor by clicking the close box in the upper left hand corner Macintosh or upper right hand corner other operating systems Now that we know more about Agent Monitors we have three ways to change an individual turtle s color Tutorial 2 Commands 43 NetLogo 4 0 User Manual One way is to use the box called an Agent Commander found at the bottom of an Agent Monitor You type commands here just like in the Command Center but the commands you type here are only done by this particular turtle e In the Agent Commander of the Turtle Monitor for turtle O type set color pink What happens in the View Did anything change in the Turtle Monitor A second way to change one turtle s color is to go directly to the color variable in the Turtle Monitor and change the value e Select the text to the right of color in the Turtle Monitor e Type in a new color such as green 2 What happened The third way to change an individual turtle s or patch s color is to use the observer Since the observer oversees the NetLogo world it can give commands that affect individual turtle
370. rtles must be located in a turtle context You can establish a turtle context in any of three ways e In a button by choosing Turtles from the popup menu Any code you put in the button will be run by all turtles e In the Command Center by choosing Turtles from the popup menu Any commands you enter will be run by all the turtles e By using ask turtles The same goes for patches links and the observer except that you cannot ask the observer Any code that is not inside any ask is by default observer code Here s an example of the use of ask in a NetLogo procedure to setup clear all ert 100 create 100 turtles ask turtles set color red turn them red rt random float 360 77 give them random headings fd 50 7 spread them around ask patches if pxcor gt 0 7 patches on the right side set pcolor green Of the view turn green end The models in the Models Library are full of other examples A good place to start looking is in the Code Examples section Usually the observer uses ask to ask all turtles all patches or all links to run commands You can also use ask to have an individual turtle patch or link run commands The reporters turtle patch link and patch at are useful for this technique For example to setup clear all erk 3 make 3 turtles ask turtle 0 tell the first one fo 1 jj to go forward ask turtle 1 tell the second one set color green 5 to become green
371. rts and also a connector for add on boards such as a display or a wireless communication module Using the GoGo Board extension NetLogo models can interact with the physical world in two ways First it can gather data from the environment such as temperature ambient light or user input This information can be used by the model to change or calibrate its behavior Secondly it can control output devices NetLogo could control motors toys remote controlled cars electrical appliances light bulbs and automated laboratory equipment How to get a GoGo Board The GoGo Board is not a commercial product and thus cannot be bought at stores To get a GoGo Board you have to build one yourself or ask someone to do it for you The board was especially designed to be easy and cheap to build even if you don t have electronics skills The main resource about the GoGo Board is the web site www gogoboard org where you will find step by step instructions on how to buy components design the printed circuit board and assemble it The GoGo Board mailing list is gogoboard yahoogroups com Installing the GoGo Extension The GoGo Board needs to communicate with the computer in some way and to do so it uses the serial port The choice of this port instead of a USB port was motivated by the board s low cost principle the components needed to build a USB compatible board would be more expensive If your computer does not have a serial port you need t
372. ry bar txt gt c foo fish bar txt show word 1 54 8 fishy gt 1 54 8 fishy show word 3 gt 3 show word a pr c 1 23 gt abcl23 world width world height world width world height These reporters give the total width and height of the NetLogo world The width equals max pxcor min pxcor 1 and the height equals max pycor min pycor 1 See also max pxcor max pycor min pxcor and min pycor NetLogo Dictionary 343 NetLogo 4 0 User Manual wrap color wrap color number wrap color checks whether number is in the NetLogo color range of O to 140 not including 140 itself If it is not wrap color wraps the numeric input to the O to 140 range The wrapping is done by repeatedly adding or subtracting 140 from the given number until it is in the 0 to 140 range This is the same wrapping that is done automatically if you assign an out of range number to the color turtle variable or pcolor patch variable show wrap color 150 gt 10 show wrap color 10 gt 130 write write value This command will output value which can be a number string list boolean or nobody to the Command Center not followed by a carriage return unlike print and show The calling agent is not printed before the value unlike show Its output will also includes quotes around strings and is prepended with a space write hello world gt hello world See also print show and type
373. ry only limits how often the commands run Above in this context means during the same ask or button press or command typed in the Command Center So it doesn t make sense to write ask turtles every 0 5 11 because when the ask finishes the turtles will all discard their timers for the every The correct usage is shown below every 0 5 ask turtles fd 1 7 twice a second the turtles will move forward 1 every 2 set index index 1 7 every 2 seconds index is incremented See also_wait exp exp number Reports the value of e raised to the number power Note This is the same as e number export view export interface export output export plot 258 NetLogo Dictionary NetLogo 4 0 User Manual export all plots export world export view filename export interface filename export output filename export plot plotname filename export all plots filename export world filename export view writes the current contents of the current view to an external file given by the string filename The file is saved in PNG Portable Network Graphics format so it is recommended to supply a filename ending in png export interface is similar but for the whole interface tab export output writes the contents of the model s output area to an external file given by the string filename If the model does not have a separate output area the output portion of the Command Center is used export plot writes the x a
374. ry small whereas other groups became very large Also the party changed over time from all mixed groups of men and women to all single sex groups What could explain this 24 Sample Model Party NetLogo 4 0 User Manual There are lots of possible answers to this question about what happens at real parties The designer of this simulation thought that groups at parties don t just form randomly The groups are determined by how the individuals at the party behave The designer chose to focus on a particular variable called tolerance erro Tolerance is defined here as the percentage of people of the opposite sex an individual is comfortable with If the individual is in a group that has a higher percentage of people of the opposite sex than their tolerance allows then they become uncomfortable and leave the group to find another group For example if the tolerance level is set at 25 then males are only comfortable in groups that are less than 25 female and females are only comfortable in groups that are less than 25 male As individuals become uncomfortable and leave groups they move into new groups which may cause some people in that group to become uncomfortable in turn This chain reaction continues until everyone at the party is comfortable in their group Note that in the model tolerance is not fixed You the user can use the tolerance slider to try different tolerance percentages and see what the o
375. ry the user for input such as user yes or no will cause a Java exception The NetLogo API Specification contains further details BehaviorSpace The Controlling API supports running BehaviorSpace experiments headless It does not support running them in BehaviorSpace s GUI although you can write your own BehaviorSpace like Java code to run your own BehaviorSpace like experiments if you want Note that it is definitely not necessary to use the API to do headless BehaviorSpace runs Headless BehaviorSpace is supported directly from the command line with no Java programming at all required See the BehaviorSpace Guide for instructions In most cases the command line support will be enough without needing to use the API In some situations though you may want additional flexibility afforded by the API The HeadlessWorkspace has four methods for running experiments three variants of runExperiment plus runExperimentFromModel runExperimentFromModel is used when the experiment setup is already stored in the model file Controlling Guide 181 NetLogo 4 0 User Manual The two forms of runExperiment that take File arguments are used when the experiment setup is stored in a standalone XML file separate from the model file If the file contains only one setup you only need to pass in the File object If the file contains multiple setups you must also pass in a String object holding the experiment name The form of runE
376. s See also however the State Machine Example model which shows how to re code Termites using ticks Even for models that would normally be set to tick based updates it may be useful to switch to continuous updates temporarily for debugging purposes Seeing what s going on within a tick instead of only seeing the end result of a tick could help with troubleshooting After switching to continuous updates you may want to use the speed slider to slow the model down until you see your agents moving one at a time Don t forget to change back to tick based updates when you are done as the choice of update mode is saved with the model Plotting NetLogo s plotting features let you create plots to help you understand what s going on in your model Before you can plot you need to create one or more plots in the Interface tab Each plot should have a unique name You ll be using its name to refer to it in your code in the Procedures tab For more information on using and editing plots in the Interface tab see the Interface Guide Specifying a plot If you only have one plot in your model then you can start plotting to it right away But if you have more than one plot you have to specify which one you want to plot to To do this use the set current plot command with the name of the plot enclosed in double quotes like this set current plot Distance vs Time You must supply the name of the plot exactly as you typed it when you created the
377. s as well as groups of turtles e In the Command Center select observer from the popup menu or use the tab key e Type ask turtle 0 set color blue and press return What happens Just as there are Turtle Monitors there are also Patch Monitors Patch monitors work very similarly to Turtle Monitors Can you make a patch monitor and use it to change the color of a single patch If you try to have the observer ask patch 0 set pcolor blue you ll get an error message 44 Tutorial 2 Commands NetLogo 4 0 User Manual Command Center A Clear ERROR Expected a number here rather than a list or block SERES ask patch 0 ICA To ask an individual turtle to do something we use its who number But patches don t have who numbers therefore we need to refer to them some other way Remember patches are arranged on a coordinate system Two numbers are needed to plot a point on a graph an x axis value and a y axis value Patch locations are designated in the same way as plotting a point e Open a patch monitor for any patch The monitor shows that for the patch in the picture its pxcor variable is 11 and its pycor variable is 4 If we go back to the analogy of the coordinate plane and wanted to plot this point the point would be found in the lower left quadrant of the coordinate plane where x 11 and y 4 To tell this particular patch to change color use its coordin
378. s lt breed gt with link neighbor link links links own lt link breeds gt own link neighbors link with my lt breeds gt my in lt breeds gt my in links my links my out lt breeds gt my out links no links other end out lt breed gt neighbor out lt breed gt neighbors out lt breed gt to out link neighbor out link neighbors out link to tie Movie movie cancel movie close movie grab view movie grab interface movie set frame rate movie start movie status System netlogo applet netlogo version Built In Variables NetLogo Dictionary 237 NetLogo 4 0 User Manual Turtles breed color heading hidden label label color pen mode pen size shape size who xcor ycor Patches pcolor plabel plabel color pxcor pycor Links breed color endi end2 hidden label label color shape thickness tie mode Other 2 Keywords breed directed link breed end globals includes patches own to to report turtles own undirected link breed Constants Mathematical Constants e 2 718281828459045 pi 3 141592653589793 Boolean Constants false true Color Constants black 0 gray 5 white 9 9 red 15 orange 25 brown 35 yellow 45 green 55 lime 65 turquoise 75 cyan 85 sky 95 238 NetLogo Dictionary NetLogo 4 0 User Manual blue 105 violet 115 magenta 125 pink 135 See the Colors section of the Programming Guide for more details A abs abs number Reports the absolute v
379. s you can edit it using the same editor by pressing the Edit button e Curviness this is the amount of bend in a link expressed in patches this is particularly useful if you have directed links going in both directions so you can discern both links e Number of lines You can have 1 2 or 3 lines in each link shape you control this by selecting line patterns in the left line middle line and right line selection boxes e Dash pattern of lines There are several dashed line patterns available in the selection boxes so not all lines need be solid Here are a few link shapes with various properties Shapes Editor Guide 151 NetLogo 4 0 User Manual Using Shapes in a Model In the model s code or in the command center you can use any of the shapes that are in the model though only turtles can have turtle shapes and only links can have link shapes For example suppose you want to create 50 turtles with the shape rabbit Provided there is some turtle shape called rabbit in this model give this command to the observer in the command center observer gt crt 50 And then give these commands to the turtles to spread them out then change their shape turtles gt fd random 15 turtles gt set shape rabbit Voila Rabbits Note the use of double quotes around the shape name Shape names are strings Similarly you can set the shape variable of links Assuming there is a link shape called road in this model observer gt cr
380. s 1 and the neighbors4 primitive gives you a Von Neumann neighborhood of radius 1 For Moore or Von Neumann neighborhoods of a larger radius see Moore amp Von Neumann Example in the Code Examples section of the Models Library How can I convert an agentset to a list of agents or vice versa If you want the list in a particular order use the sort or sort by primitives The Lists section of the Programming Guide explains how to do this See also Ask Ordering Example in the Code Examples section of the Models Library If you want the list in a random order here s how self of lt agentset gt Because all operations on agentsets are in random order the resulting list is in random order To convert a list of agents to an agentset use the turtle set patch set or link set primitives How do stop foreach To stop a foreach from executing you need to define a separate procedure that contains only the foreach for example to test foreach if print end 1 2 2 3 stop This code will only print the number 1 The stop returns from the current procedure so nothing after the foreach will be executed either If the procedure is a reporter procedure use report instead of stop BehaviorSpace FAQ Frequently Asked Questions 233 NetLogo 4 0 User Manual How do measure runs every n ticks Use repeat in your experiment s go commands e g repeat 100 go to measure the run after every 100 mod
381. s a list reports a new list containing the same items as the input list in a sorted order defined by the boolean true or false reporter In reporter use 21 and 2 to refer to the two objects being compared reporter should be true if 21 comes strictly before 2 in the desired sort order and false otherwise If the input is an agentset or a list of agents reports a list never an agentset of agents The sort is stable that is the order of items considered equal by the reporter is not disturbed show sort by 1 lt 2 3 1 4 2 gt 1 2 3 4 show sort by 1 gt 2 3 1 4 2 gt 4 3 2 1 show sort by length 21 lt length 22 Grumpy Doc Happy gt Doc Happy Grumpy foreach sort by size of 1 lt size of 2 turtles ask do something turtles run do something one at a time in 77 ascending order by size sprout sprout lt breeds gt sprout number commands Bj lt breeds gt number commands Creates number new turtles on the current patch The new turtles have random colors and headings and they immediately run commands This is useful for giving the new turtles different colors headings or whatever The new turtles are created all at once then run one at a time in random order If the sprout lt breeds gt form is used the new turtles are created as members of the given breed sprout 5 sprout wolves 10 sprout 1 set color red sprout sheep 1 set color blac
382. s for each topology given that the min and max pxcor and pycor are 2 e Torus sqrt 2 1 414 this will be the same for all world sizes since the patches are directly diagonal to each other in a torus e Box sqrt world width 2 world height 2 7 07 e Vertical Cylinder sqrt world height 2 1 5 099 e Horizontal Cylinder sqrt world width 2 1 5 099 All the other primitives will act similarly to distance If you formerly used no wrap primitives in your model we recommend removing them and changing the topology of the world instead There are a number of reasons to change your model to use topologies rather than no wrap primitives First we expect if you are using no wrap primitives you are actually modeling a world that is not a torus If you use a topology that matches the world you are modeling NetLogo does automatic bounds checking for you it should make your life easier your code simpler to understand and it adds visual cues to help the model user understand what you are modeling Note that even with no wrap primitives it was very difficult to model cylinders since the no wrap primitives report the distance or heading when wrapping is not allowed in either direction You might have bugs in your model If you are using a combination of no wrap and wrap primitives either it doesn t matter for some reason or there is a bug in your model we found a few bugs in our models For example the Conductor m
383. s issued To tell which version of the Extension API your NetLogo supports choose the About NetLogo item in the Help menu Or you can launch the NetLogo jar with the extension api version argument Here s a manifest for our example extension manifest txt anifest Version 1 0 Extension Name exampl Class Manager SampleExtension tLogo Extension API Version 4 0 The NetLogo Extension API Version line should match the actual version of NetLogo Extension API you are using Make sure even the last line ends with a newline character 4 Create a JAR To create an extension s JAR file first compile your classes as usual either from the command line or using an IDE Important You must add Net Logo jar from the NetLogo distribution to your classpath when compiling Here s an example of how compiling your extension might look from the command line mkdir p classes create the classes subfolder if it does not exist S javac classpath NetLogo jar d classes src IntegerList java src SampleExtension java You will need to change the classpath argument to point to the NetLogo jar file from your NetLogo installation This command line will compile the java and put the class files in the classes subfolder Then create a JAR containing the resulting class files and the manifest For example jar cvfm example jar manifest txt C classes For information about manifest files JAR files and Java too
384. s one Otherwise does nothing clear patches cp clear patches is Clears the patches by resetting all patch variables to their default initial values including setting their color to black clear plot clear plot In the current plot only resets all plot pens deletes all temporary plot pens resets the plot to its default values for x range y range etc and resets all permanent plot pens to their default values The default values for the plot and for the permanent plot pens are set in the plot Edit dialog which is displayed when you edit the plot If there are no plot pens after deleting all temporary pens that is to say if there are no permanent plot pens a default plot pen will be created with the following initial settings e Pen down e Color black e Mode O line mode e Name default e Interval 1 See also clear all plots clear turtles ct 248 NetLogo Dictionary NetLogo 4 0 User Manual clear turtles w Kills all turtles Also resets the who numbering so the next turtle created will be turtle 0 See also die color color ae This is a built in turtle or link variable It holds the color of the turtle or link You can set this variable to make the turtle or link change color See also_pcolor cos cos number Reports the cosine of the given angle Assumes the angle is given in degrees show cos 180 gt 1 count count agentset Reports the number of agents in the given
385. s only the agents on the patches the given distances away from the calling agent The distances are specified as a list of two item lists where the two items are the x and y offsets If the caller is the observer then the points are measured relative to the origin in other words the points are taken as absolute patch coordinates If the caller is a turtle the points are measured relative to the turtle s exact location and not from the center of the patch under the turtle ask turtles at points 2 4 1 2 10 15 ta sh 7 only the turtles on the patches at the 7 distances 2 4 1 2 and 10 15 relative to the caller mov 242 NetLogo Dictionary NetLogo 4 0 User Manual atan atan x y Reports the arc tangent in degrees from 0 to 360 of x divided by y When y is 0 if x is positive it reports 90 if x is negative it reports 270 if x is zero you get an error Note that this version of atan is designed to conform to the geometry of the NetLogo world where a heading of 0 is straight up 90 is to the right and so on clockwise around the circle Normally in geometry an angle of 0 is right 90 is up and so on counterclockwise around the circle and atan would be defined accordingly show atan 1 1 gt 135 show atan 1 1 gt 315 autoplot autoplot Reports true if auto plotting is on for the current plot false otherwise auto plot off auto plot on auto plot off auto plot on This pair of co
386. s simple it means me myself means the turtle or patch who asked me to do what I m doing right now When an agent has been asked to run some code using myself in that code reports the agent turtle or patch that did the asking myself is most often used in conjunction with of to read or set variables in the asking agent myself can be used within blocks of code not just in the ask command but also hatch sprout of with min one of and max one of ask turtles ask patches in radius 3 set pcolor color of myself 7 each turtle makes a colored splotch around itself See the Myself Example code example for more examples See also self N n of n of size agentset n of size list From an agentset reports an agentset of size size randomly chosen from the input set with no repeats From a list reports a list of size size randomly chosen from the input set with no repeats The items in the result appear in the same order that they appeared in the input list If you want them in random order use shuffle on the result It is an error for size to be greater than the size of the input ask n of 50 patches set pcolor green 296 NetLogo Dictionary NetLogo 4 0 User Manual 7 50 randomly chosen patches turn green See also one of n values n values size reporter Reports a list of length size containing values computed by repeatedly running reporter In reporter use_ to refer to the number of
387. s successful gogo output port coast gogo output port coast Turns off the power of the active ports When attached to motors does not apply a braking force as gogo output port off does Therefore the motor will gradually slow down before stopping completely This will have the same effect as gogo output port off on most output devices other than motors The output ports effected by this command are determined by the gogo talk to output poris command The following code will will turn on output port a for 1 second and then stop the motor gradually gogo talk to output ports a gogo output port on wait 1 gogo output port coast gogo output port off gogo output port off Turns off power to the output ports If using motors a braking force is applied The output ports effected by this command are determined by the gogo talk to output ports command GoGo Extension 207 NetLogo 4 0 User Manual gogo output port reverse gogo output port reverse Reverses the direction of the output ports The output ports effected by this command are determined by the gogo talk to output ports command gogo output port that this way gogo output port thatway gogo output port thisway Apply power to the output port in a given direction Output ports can be powered in two directions arbitrarily called thisway and thatway The output ports effected by the command are determined by the gogo talk to output ports command Note that this is different
388. s that will be in the majority of HubNet Activities You should be able to use this activity as a starting point for most projects Setup To make a NetLogo model into a HubNet activity you must first initialize the network In most HubNet activities you will use the startup procedure to initialize the network Startup is a special procedure NetLogo will try to run the startup procedure when you open any model That makes it a good place to put code that you want to run once and only once no matter how many times the user runs the model For HubNet we put the commands that initialize the network in startup because once the network is setup we don t need to do so again First specify the type of clients using hubnet set client interface in this case we will be using computer clients hubnet set client interface COMPUTER Then initialize the system using hubnet reset which will ask the user for a session name and open up the HubNet Control Center NetLogo is now ready to start listening for client messages HubNet Authoring Guide 169 NetLogo 4 0 User Manual Now that the network is all setup you don t need to worry about calling hubnet set client interface or hubnet reset again Take a look at the setup procedure in the template model to setup cp cd clear output ask turtles set step size 1 hubnet send user id step size step siz end For the most part it looks like most other setup procedures ho
389. s the exclusive time in milliseconds that procedure name was running for Exclusive time is the time from when the procedure was entered until it finishes but does not include any time spent in other user defined procedures which it calls If procedure name is not defined then reports 0 profiler inclusive time profiler calls procedure name Reports the inclusive time in milliseconds that procedure name was running for Inclusive time is the time from when the procedure was entered until it finishes If procedure name is not defined then reports 0 profiler start profiler start Instructs the profiler to begin recording user defined procedure calls profiler stop profiler stop Instructs the profiler to stop recording user defined procedure calls profiler reset profiler reset Instructs the profiler to erase all collected data profiler report profiler report Reports a string containing a breakdown of all user defined procedure calls The Calls column contains the number of times a user defined procedure was called The Incl T ms column is the total time in milliseconds it took for the call to complete including the time spent in other user defined procedures The Excl T ms column is the total time in milliseconds spent within that user defined procedure not counting other user define procedures it called The Excl calls column is an estimate of the time in milliseconds spent in that user defined proced
390. s work in NetLogo 0 all numbers are now double precision floating point numbers with no fractional part print as integers without the decimal point much larger integers can now be represented up to about 9x10 15 new primitive of replaces VARIABLE of value from values from new reporter al1 tests whether all agents in an agentset satisfy a condition turtle who numbers are now never reused until clear turtles Of clear all new primitive other reports an agentset excluding the calling agent this is short for with self myself removed other turtles here and other lt breeds gt here from language use other instead new move to command moves a turtle to the location of the specified turtle or patch for commands that create turtles or links the commands following are now optional create custom turtles and create custom lt breeds gt no longer exist instead use create turtles and create lt breeds gt which now take an optional command block create turtles now makes turtles with random headings and colors to get evenly spaced turtles with sequential colors and id numbers use create ordered turtles cro for short new turtle set patch set and link set reporters let you build agentsets in a variety of ways removed turtles from and patches from from language use turtle set and patch set instead new uphill uphill4 downhill and downhi114 commands for doing hill climbing 0 these new commands replace the old reporters with the same na
391. show patch 1 2 3 7 7 prints patch 1 4 note rounding show patch 18 19 77 Supposing min pxcor and min pycor are 17 7 and max pxcor and max pycor are 17 7 in a wrapping topology prints patch 17 16 in a non wrapping topology prints nobody See also_patch at patch ahead patch ahead distance Reports the single patch that is the given distance ahead of the calling turtle that is along the turtle s current heading Reports nobody if the patch does not exist because it is outside the world ask patch ahead 1 set pcolor green 7 turns the patch 1 in front of the calling turtle a green note that this might be the same patch i the turtle is standing on See also patch at patch left and ahead patch right and ahead patch at heading and distance patch at patch at dx dy aH Reports the patch at dx dy from the caller that is the patch containing the point dx east and dy patches north of the calling agent Reports nobody if there is no such patch because that point is beyond a non wrapping world boundary ask patch at 1 1 set pcolor green 7 if caller is a turtle or patch turns the i3 patch just southeast of the caller green See also patch patch ahead patch left and ahead patch right and ahead patch at heading and distance patch at heading and distance patch at heading and distance heading distance patch at heading and distance reports the single patch that is the given dist
392. side of the panel which shows the origin and the boundaries The width and height of the world are displayed below the preview Also below the preview there are two checkboxes the world wrap settings These allow you to control the topology of the world Notice when you click the check boxes the preview indicates which directions allow wrapping and the name of the topology is displayed next to the world dimensions See the Topology Section of the Programming Guide for more information The view settings allow you to customize the look of the view without changing the world Changing view settings will never force a world reset To change the size of the 2D View adjust the Patch Size setting measured in pixels This does not change the number of patches only how large the patches appear in the 2D View Note that the patch size does not affect the 3D View as you can simply make the 3D View larger by making the window larger The Turtle Shapes checkbox lets you turn turtle shapes on and off If shapes are off turtles appear as colored squares instead of having special shapes The squares are less work for the computer to draw so turning shapes off makes models run faster The Smooth edges checkbox controls the use of anti aliasing in the 3D view only and only appears when editing from the 3D view It will make the lines appear less jagged but it will slow down the model Tick counter settings control the appearance of the tick counter
393. sitive amount including fractional amounts Some Models Library models that use tick advance are 138 Transition Guide NetLogo 4 0 User Manual Vector Fields and the GasLab models The value of the tick counter is displayed in the toolbar at the top of the Interface tab You can use the Settings button in the toolbar to hide the tick counter or change the word ticks to something else View update modes In the past NetLogo always tried to update the view about 20 times a second We re now calling that continuous view updates The biggest problem with it was that you usually want updates to happen between model ticks not in the middle of a tick so we had a checkbox on buttons that by default forced a display update after every button iteration That made sure updates happened between ticks but it didn t get rid of the intermediate updates You had to use no display and display to lock them out We still support continuous updates They are the default when you start up NetLogo But most Models Library models now use tick based updates With tick based updates updates happen only when the tick counter advances The display command can be used to force additional updates see below The advantages of tick based updates as we see them are as follows 1 Consistent predictable view update behavior which does not vary from computer to computer or from run to run 2 Intermediate updates can confuse the user of your model b
394. sk turtles says that each turtle should run the commands in the brackets e right random 360 is another command that uses a reporter First each turtle picks a random whole number between 0 and 359 random doesn t include the number you give it as a possible result Then the turtle turns right this number of degrees e forward 1 makes the turtle move forward one step Why couldn t we have just written all of these commands in go instead of in a separate procedure We could have but during the course of building your project it s likely that you ll add many other parts We d like to keep go as simple as possible so that it is easy to understand Eventually it will include many other things you want to have happen as the model runs such as calculating something or plotting the results Each of these things to do will have its own procedure and each procedure will have its own unique name The go button you made in the Interface tab is a forever button meaning that it will continually run its commands until you shut it off by clicking on it again After you have pressed setup once to create the turtles press the go button Watch what happens Turn it off and you ll see that all the turtles stop in their tracks Note that if a turtle moves off the edge of the world it wraps that is it appears on the other side This is the default behavior It can be changed see the_Topology section of the Programming Guide for more
395. so from the NetLogo distribution must be in same location it contains additional libraries used by Net Logo jar Note the use of Event Queue invokeAndWait to ensure that a method is called from the right thread This is because most of the methods on the App class may only be called some certain threads Most of the methods may only be called from the AWT event queue thread but a few methods such as commmand may only be called from threads other than the AWT event queue thread such as in this example the main thread Rather than continuing to discuss this example in full detail we refer you to the NetLogo API Specification which documents all of the ins and outs of the classes and methods used above Additional methods are available as well Example headless The example code in this case is very similar to the previous example but with methods on an instance of the HeadlessWorkspace Class substituted for static methods on App import org nlogo headless HeadlessWorkspace public class Example2 public static void main String argv HeadlessWorkspace workspace new HeadlessWorkspace try workspace open models Sample Models Earth Science Fire nlogo workspace command set density 62 workspace command random seed 0 workspace command setup workspace command repeat 50 go System out println workspace report burned trees 180 Controlling Guide NetLogo 4 0 User M
396. specifics about writing procedures refer to the Programming Guide All of the primitives are listed and described in the the NetLogo Dictionary Also you can continue experimenting with and expanding this model if you d like experimenting with different variables and behaviors for the agents Alternatively you may want to revisit the first model in the tutorial Wolf Sheep Predation This is the model you used in Tutorial 1 Inthe Wolf Sheep Predation model you saw sheep move around consume resources that are replenished occasionally grass reproduce under certain conditions and die if they ran out of resources But that model had another type of creature moving around wolves The addition of wolves requires some additional procedures and some new primitives Wolves and sheep are two different breeds of turtle To see how to use breeds study Wolf Sheep Predation Alternatively you can look at other models including the many models in the Code Examples section of the Models Library or even go ahead and build your own model You don t even have to model anything It can be interesting just to watch patches and turtles forming patterns to try to create a game to play or whatever Hopefully you have learned some things both in terms of the NetLogo language and about how to go about building a model The entire set of procedures that was created above is shown below Appendix Complete code The complete model is also availabl
397. ss mode for command line operation e editor highlights matching parentheses and brackets e action keys let buttons be triggered by keypresses e makes QuickTime movies of models e add output area to models e improved shapes editor and built in shapes e new primitives including let and carefully e computer HubNet now more reliable clients automatically find server improved client interface and Control Center Version 2 0 2 August 2004 e extensions API for writing commands and reporters in Java e controlling API for controlling NetLogo from external Java code e sound extension for making sounds and music Version 2 0 December 2003 14 e full support for Mac OS X and Linux e Windows 95 MacOS 8 9 no longer supported e improved look and feel e fast flicker free non grid based graphics What s New NetLogo 4 0 User Manual e primitives for reading and writing external files e strict math mode for identical results cross platform e export view or interface tab as image file e improved BehaviorSpace e computer HubNet no longer alpha Version 1 3 June 2003 e view control strip e choosers e new primitives including run runresult map foreach filter reduce e some primitives accept a variable number of inputs Version 1 2 March 2003 e much improved speed e computer HubNet alpha Version 1 1 July 2002 e Save as Applet lets you embed your model in any web page e printer support e Proc
398. ss computation per time step If you need help with this if you contact us at feedback ccl northwestern edu we may be able to help if you can send us your model or give us some idea of how it works The members of the NetLogo Users Group may be able to help as well Note that using run and runresult are much slower than running code directly you should avoid using these primitives in performance critical code Can I have more than one model open at a time One instance of NetLogo can only have one model open at a time We plan to change this in a future version You can have multiple models open by opening multiple instances of NetLogo though On Windows and Linux simply start the application again On a Mac you ll need to duplicate the application in the Finder then open the copy The copy takes up only a very small amount of additional disk space Can change the choices in a chooser on the fly At present no In a future version of NetLogo we plan to support this FAQ Frequently Asked Questions 227 NetLogo 4 0 User Manual Can divide the code for my model up into several files Yes this is available on an experimental basis using the __ includes keyword How do show the legend in a plot Click the word Pens in the upper right corner of the plot The legend will include any pens that have the Show in Legend option checked when editing the plot Clicking Pens again will hide the legend Programming H
399. staff and our various research activities Feedback Questions Etc If you need help with your model consider posting to the NetLogo users group at htto groups yahoo com group netlogo users We also have a group specifically for educators at http groups yahoo com group netlogo educators If you have feedback suggestions or questions write us at feedback ccl northwestern edu Reporting Bugs If you would like to report a bug that you find in NetLogo write to bugs ccl northwestern edu When submitting a bug report please try to include as much of the following information as possible e A complete description of the problem and how it occurred e The NetLogo model or code you are having trouble with If possible attach a complete model e Your system information NetLogo version OS version Java version and so on This information is available from NetLogo s About NetLogo menu item then clicking the System tab In saved applets the same information is available by control clicking Mac or right clicking the white background of the applet e Any error messages that were displayed Contacting Us 21 22 NetLogo 4 0 User Manual Contacting Us Sample Model Party This activity is designed to get you thinking about computer modeling and how you can use it It also gives you some insight into the NetLogo software We encourage beginning users to start with this activity At a Party Have you ever been at a
400. stem in a rapid and flexible way that would be difficult to do in a real world situation Modeling also gives you the opportunity to observe a situation or circumstance with less prejudice as you can examine the underlying dynamics of a situation You may find that as you model more and more many of your preconceived ideas about various phenomena will be challenged For example a surprising result of the Party model is that even if tolerance is relatively high a great deal of separation between the sexes occurs This is a classic example of an emergent phenomenon where a group pattern results from the interaction of many individuals This idea of emergent phenomena can be applied to almost any subject What other emergent phenomena can you think of To see more examples and gain a deeper understanding of this concept and how NetLogo helps learners explore it you may wish to explore NetLogo s Models Library It contains models that demonstrate these ideas in systems of all kinds For a longer discussion of emergence and how NetLogo helps learners explore it see_ Modeling Nature s Emergent Patterns with Multi agent Languages Wilensky 2001 What s Next The section of the User Manual called_Tutorial 1 Running Models goes into more detail about how to use the other models in the Models Library If you want to learn how to explore the models at a deeper level Tutorial 2 Commands will introduce you to the NetLogo modeling la
401. t but in randomized order show shuffle gt 5241 3 show shuffle gt 13524 12 3 4 5 1 2 3 4 5 NetLogo Dictionary 325 NetLogo 4 0 User Manual sin sin number Reports the sine of the given angle Assumes angle is given in degrees show sin 270 gt 1 size size x This is a built in turtle variable It holds a number that is the turtle s apparent size The default size is 1 which means that the turtle is the same size as a patch You can set this variable to change a turtle s size sort sort list of numbers sort list of strings sort agentset If the input is a list of numbers or strings reports a new list containing the same items as the input list but in ascending order numeric or alphabetic Any list items that are not numbers or strings are ignored If the input list contains no numbers or strings the result is an empty list If the input is an agentset or a list of agents reports a list never an agentset of agents If the agents are turtles they are listed in ascending order by who number If the agents are patches they are listed left to right top to bottom show sort 3 1 4 2 gt 1 2 3 4 let n 0 foreach sort patches ask set plabel n set nn 1 7 patches are labeled with numbers in left to right 7 top to bottom order sort by sort by reporter list sort by reporter agentset 326 NetLogo Dictionary NetLogo 4 0 User Manual If the input i
402. t 5 create links with other turtles turtles gt fd 5 links gt set shape road The set default shape command is also useful for assigning shapes to turtles and links 152 Shapes Editor Guide BehaviorSpace Guide This guide has three parts e What is BehaviorSpace A general description of the tool including the ideas and principles behind it e How It Works Walks you through how to use the tool and highlights its most commonly used features e Advanced Usage How to use BehaviorSpace from the command line or from your own Java code What is BehaviorSpace BehaviorSpace is a software tool integrated with NetLogo that allows you to perform experiments with models It runs a model many times systematically varying the model s settings and recording the results of each model run This process is sometimes called parameter sweeping It lets you explore the model s space of possible behaviors and determine which combinations of settings cause the behaviors of interest Why BehaviorSpace The need for this type of experiment is revealed by the following observations Models often have many settings each of which can take a range of values Together they form what in mathematics is called a parameter space for the model whose dimensions are the number of settings and in which every point is a particular combination of values Running a model with different settings and sometimes even the same ones can lead to drastically d
403. t breed gt from turtle create lt breed gt from turtle commands create lt breed gt with turtle create lt breed gt with turtle commands create lt breeds gt to turtleset create lt breeds gt to turileset commands create lt breeds gt from turtleset create lt breeds gt from turtleset commands create lt breeds gt with turtleset create lt breeds gt with turtleset commands create link to turtle create link to turtle commands create link from turtle create link from turtle commands create link with turtle create link with turtle commands create links to turtleset create links to turtleset commands create links from turtleset create links from turtleset commands create links with turtleset create links with turileset commands 250 NetLogo Dictionary NetLogo 4 0 User Manual Used for creating breeded and unbreeded links between turtles create link with creates an undirected link between the caller and agent create link to creates a directed link from the caller to agent create link from creates a directed link from agent to the caller When the plural form of the breed name is used an agentset is expected instead of an agent and links are created between the caller and all agents in the agentset The optional command block is the set of commands each newly formed link runs The links are created all at once then run one at a time in random order A node cannot be linked
404. t color blue 7 turtles in the right half of the world 7 turn blue See also ifelse ifelse value ifelse ifelse reporter commands commands2 Reporter must report a boolean true or false value If reporter reports true runs commands If reporter reports false runs commands2 The reporter may report a different value for different agents so some agents may run commands1 while others run commands2 ask patches ifelse pxcor gt 0 set pcolor blue set pcolor red the left half of the world turns red and the right half turns blue See also if ifelse value 274 NetLogo Dictionary NetLogo 4 0 User Manual ifelse value ifelse value reporter reporter1 reporter2 Reporter must report a boolean true or false value If reporter reports true the result is the value of reporter If reoorter reports false the result is the value of reporter2 This can be used when a conditional is needed in the context of a reporter where commands such as ifelse are not allowed ask patches set pcolor ifelse value pxcor gt 0 blue red 7 the left half of the world turns red and 7 the right half turns blue show n values 10 ifelse value lt 5 0 1 gt 0000011111 show reduc ifelse valu 21 gt 22 21 22 1 3 2 5 38 3 2 1 gt 8 See also if ifelse import drawing import drawing filename Reads an image file into the drawing scaling it to the size
405. t variable value Sets variable to the given value Variable can be any of the following 320 NetLogo Dictionary NetLogo 4 0 User Manual e A global variable declared using globals e The global variable associated with a slider switch chooser or input box e A variable belonging to the calling agent e If the calling agent is a turtle a variable belonging to the patch under the turtle e A local variable created by the let command e An input to the current procedure e A special local variable 21 2 set current directory set current directory string Sets the current directory that is used by the primitives file delete file exists and file open The current directory is not used if the above commands are given an absolute file path This is defaulted to the user s home directory for new models and is changed to the model s directory when a model is opened Note that in Windows file paths the backslash needs to be escaped within a string by using another backslash CN The change is temporary and is not saved with the model Note in applets this command has no effect since applets are only allowed to read files from the same directory on the server where the model is stored set current directory C NetLogo Assume it is a Windows Machine file open my file txt Opens file C NetLogo my file txt set current plot set current plot plotname Sets the current plot to the plot with th
406. t your model to use ticks and tick based updates in NetLogo 4 0 Transition Guide 139 NetLogo 4 0 User Manual 1 In the Interface tab toolbar on the right hand side where it says update view change the setting from continuously to on ticks 2 Add the tick command to your go procedure at or near the end In Models Library models we always put tick after the agents move but before any plotting commands That s because the plotting commands might contain something like plotxy ticks and we want the new value of the tick counter used not the old one Most models don t refer to the tick counter in their plotting commands but nonetheless for consistency and to avoid mistakes we suggest always putting tick before the plotting commands Some models will require some additional changes 1 If your model already has a global ticks or clock or time variable get rid of it Use the tick command and ticks reporter instead If your model uses fractional increments of time use tick advance instead of tick If you had a monitor for that variable you can get rid of it there s now a tick counter in the toolbar 2 clear al1 resets the tick counter to zero If you don t use clear al1 in your setup procedure then you may need to add reset ticks to reset the counter to zero 3 If you used no display and display to prevent view updates from happening in the middle of go you can get rid of them 4 lf your model needs to update the v
407. tLogo 4 0 User Manual Macintosh only bugs e When opening a model from the Finder by double clicking on it or dragging it onto the NetLogo icon if NetLogo is not already running then the model may or may not open the bug is intermittent If NetLogo is already running the model always opens e On Mac OS X 10 4 only the Copy View and Copy Interface items may not work the resulting image is distorted The workaround is to use the Export View and Export Interface items instead This issue will go away if you use Software Update to get the latest Java from Apple e On versions of Mac OS X prior to 10 4 it is possible for NetLogo s menus to get confused so that the Quit item does not work If this happens you can quit NetLogo by pressing the red close button on the left end of the NetLogo s title bar Linux UNIX only bugs e User Manual always opens in Mozilla not your default browser One possible workaround is to bookmark the file docs index html in your favorite browser Another workaround is to make a symlink that s called mozilla that s the command name NetLogo tries to run but actually runs a different browser e We have discovered a problem on Linux where the exp reporter sometimes returns a slightly different answer differing only in the last decimal place for the same input According to an engineer at Sun this should only happen on Linux kernel versions 2 4 19 and earlier but we have observed the problem on m
408. tag Example lt experiments gt lt experiment name experiment repetitions 10 runMetricsEveryStep true gt lt setup gt setup lt setup gt lt go gt go lt go gt lt exitCondition gt not any fires lt exitCondition gt lt metric gt burned trees lt metric gt lt enumeratedValueSet variable density gt lt value value 40 gt lt value value 0 1 gt lt value value 70 gt lt enumeratedValueSet gt lt experiment gt lt experiments gt In this example only one experiment setup is given but you can put as many as you want between the beginning and ending experiments tags Between looking at the DTD and looking at examples you create in the GUI it will hopefully be apparent how to use the tags to specify different kind of experiments The DTD specifies which tags are required and which are optional which may be repeated and which may not and so forth When XML for experiment setups is included in a model file it does not begin with any XML headers because not the whole file is XML only part of it If you keep experiment setups in their own file separate from the model file then the extension on the file should be xml not nlogo and you ll need to begin the file with proper XML headers as follows lt xml version 1 0 encoding us ascii gt lt DOCTYPE experiments SYSTEM behaviorspace dtd gt The second line must be included exactly as shown In the first line you may s
409. tch the turtle is standing on See also patch patch at patch at heading and distance patch set patch set value1 patch set value value Reports an agentset containing all of the patches anywhere in any of the inputs The inputs may be individual patches patch agentsets nobody or lists or nested lists containing any of the above patch set self patch set patch here patch set self neighbors patch set patch here neighbors patch set patch 0 0 patch 1 3 patch 4 2 NetLogo Dictionary 305 NetLogo 4 0 User Manual patch set patch at 1 1 patch at 0 1 patch at 1 1 patch set patch here of turtles patch set neighbors of turtles See also turtle set link set patches patches Reports the agentset consisting of all patches patches own patches own var This keyword like the globals breed lt breed gt own and turtles own keywords can only be used at the beginning of a program before any function definitions It defines the variables that all patches can use All patches will then have the given variables and be able to use them All patch variables can also be directly accessed by any turtle standing on the patch See also globals turtles own breed lt breeds gt own pcolor Ei This is a built in patch variable It holds the color of the patch You can set this variable to make the patch change color All patch variables can be directly accessed by any turtle standing on
410. te lt breeds gt number create lt breeds gt number commands Creates number new turtles New turtles have random headings and the color is randomly selected from the 14 primary colors If the create lt breeds gt form is used the new turtles are created as members of the given breed If commands are supplied the new turtles immediately run them commands This is useful for giving the new turtles a different color heading or whatever The new turtles are created all at once then run one at a time in random order crt 100 fd 10 makes a circle breed canaries canary breed snakes snake to setup clear all create canaries 50 set color yellow create snakes 50 set color green end Note While the commands are running no other agents are allowed to run any code as with the without interruption command This ensures that if ask concurrent is being used the new turtles cannot interact with any other agents until they are fully initialized See also_hatch sprout create tem porary plot pen create temporary plot pen string A new temporary plot pen with the given name is created in the current plot and set to be the current pen Few models will want to use this primitive because all temporary pens disappear when clear plot or clear all plots are called The normal way to make a pen is to make a permanent pen in the plot s Edit dialog If a temporary pen with that name already exists in the current plot
411. ted These buttons are especially handy in conjunction with the Duplicate button if you want to make shapes that are symmetrical For example if you were making a butterfly you could draw the butterfly s left wing with the polygon tool then duplicate the wing with the Duplicate button then turn the copy into a right wing with the Flip Horizontal button Shape Design It s tempting to draw complicated interesting shapes but remember that in most models the patch size is so small that you won t be able to see very much detail Simple bold iconic shapes are usually best 150 Shapes Editor Guide NetLogo 4 0 User Manual Keeping a Shape When the shape is done give it a name and press the Done button at the bottom of the editing window The shape and its name will now be included in the list of shapes along with the default shape Creating and Editing Link Shapes Managing link shapes is very similar to managing turtle shapes So you can create a new shape but pressing the New button or you can edit existing shapes when you are done editing a shape press Done if you want to keep it Changing Link Shape Properties There are several different properties for each link shape that you are allowed to change e Name link shapes can have the same name as turtle shapes but must be unique among link shapes e Direction Indicator the direction indicator the little arrow on directed links is just like the turile vector shape
412. th the given index ranging from zero to the length of the array minus one to the given value Note that unlike the replace item primitive for lists a new array is not created The given array is actually modified array length array length array Reports the length of the given array that is the number of items in the array array to list array to list array Reports a new list containing the same items in the same order as the given array Table Primitives table clear table from list table get table has key table keys table length table make table put table remove table to list table clear table clear table Removes all key value pairs from table table from list table from list list Reports a new table with the contents of ist list must be a list of two element lists or pairs The first element in the pair is the key and the second element is the value table get Array and Table Extensions 197 NetLogo 4 0 User Manual table get table key Reports the value that key is mapped to in the table Causes an error if there is no entry for the key table has key table has key table key Reports true if key has an entry in table table keys table keys table Reports a list of all the keys in table table length table length table Reports the number of entries in table table make table make Reports a new empty table table put table put table key value Maps key to value in table If an entry alr
413. the user opens a new model The XMLFileAppender also does some formatting and writes the appropriate headers to the file The layout defines how to write each individual message Unless you are an advanced user there is no need change or worry about the appender or the layout At the end of the configuration notice the definition of the root logger All of the other loggers descend from the root logger and thus inherit the properties of the root unless explicitly set This case is fairly simple having set up the appender A1 we make that the default appender for the root and all other loggers and make the default priority INFO Messages that are logged at the INFO level or higher will be written messages logged at lower levels will not Note that with only one exception NetLogo always logs at level INFO Sets to globals that don t change the value of the global are logged at level DEBUG Which means that these messages are disabled by default since debug is lower level than info The rest of the body of the configuration file overrides properties of the root logger in a few specific loggers or categories as they are known in the configuration file the terms can be assumed to be synonymous for the proposes of this document That is it turns off the WIDGET TURTLES and LINKS loggers by default To re enable them you can changes the priority from off to info like this lt category name org nlogo api Logger TURTLES gt lt priority value
414. the following terms of usage for this software distribution All but a few source code files in this distribution fall under this license the exceptions contain open source licenses embedded in the source code files themselves In this license the Authors means the Copyright Holders listed above and the license itself is Copyright 2003 by Sean Luke The Authors hereby grant you a world wide royalty free non exclusive license subject to third party intellectual property claims to use reproduce modify display perform sublicense and distribute all or any portion of the source code or binary form of this software or related data with or without modifications or as part of a larger work and under patents now or hereafter owned or controlled by the Authors to make have made use and sell Utilize all or any portion of the source code or binary form of this software or related data but solely to the extent that any such patent is reasonably necessary to enable you to Utilize all or any portion of the source code or binary form of this software or related data and not to any greater extent that may be necessary to Utilize further modifications or combinations In return you agree to the following conditions If you redistribute all or any portion of the source code of this software or related data it must retain the above copyright notice and this license and disclaimer If you redistribute all or any portion of this code in binary form y
415. the pixels below it in the drawing To erase the whole drawing use the observer commmand clear drawing You can also use clear al1 which clears everything else too Importing an image The observer command import drawing command allows you to import an image file from disk into the drawing 120 Programming Guide NetLogo 4 0 User Manual import drawing is useful only for providing a backdrop for people to look at If you want turtles and patches to react to the image you should use import pcolors or import pcolors rgb instead Comparison to other Logos Drawing works somewhat differently in NetLogo than some other Logos Notable differences include e New turtles pens are up not down e Instead of using a fence command to confine the turtle inside boundaries in NetLogo you edit the world and turn wrapping off e There is no screen color bgcolor or setbg You can make a solid background by coloring the patches e g ask patches set pcolor blue Drawing features not supported by NetLogo e There is no window command This is used in some other Logos to let the turtle roam over an infinite plane e There is no flood or fill command to fill an enclosed area with color Topology The topology of the NetLogo world has four potential values torus box vertical cylinder or horizontal cylinder The topology is controlled by enabling or disabling wrapping in the x or y directions The default world is a torus as were al
416. the web server Applets cannot browse web server or the user s computer meaning that user file anduser new file do nothing in an applet All files required to run your model including the model file itself and NetLogoLite jar must be readable by the web server user On some systems you can test the applet locally on your computer before uploading it to a web server It doesn t work on all systems though so if it doesn t work from your hard drive please try uploading it to a web server You don t need to include everything in the html file in your page If you want you can just take the HTML code beginning with lt applet gt and ending with lt applet gt and paste it into any HTML file you want It s even OK to put multiple lt applet gt tags on a single page If NetLogoLite jar and your model are in different directories you must modify the archive and value lines in the HTML code to point to their actual locations For example if you have multiple applets in different directories on the same web server you may want to put a single copy of NetLogoLite jar in one central place and change the archive lines of all the HTML files to point to that one central copy This will save disk space for you and download time for your users Java Requirements Getting the right version Current versions of NetLogo require that your web browser support Java 1 4 1 or higher Here s how to get the right Java e If you re on Windows 98 or newer
417. ther with nothing in between them That s an empty string If a turtle s label is an empty string no text is attached to the turtle e Test this in the Interface tab by running the model using the setup and go buttons switching the snow energy switch back and forth 58 Tutorial 3 Procedures NetLogo 4 0 User Manual When the switch is on you ll see the energy of each turtle go up each time it eats grass You ll also see its energy going down whenever it moves 20070 400 0 0 at 0 0 sso 500 55070 8000 4000 250 0 j 450 y 450 cd 4500 gt E m ME 0 700900 150 fi 250 5500 500 E B00 4500 300 s000 7000 200 400 400 300 45900 95040 4008500 ae art 900 s 00 008 Enqesom amoo PM AP conto 10500 6000 8500 5500 4000 8000 oo y 400 More procedures Now our turtles are eating let s make them reproduce and die too Let s also make the grass grow back We ll add all three of these of these behaviors now by making three separate procedures one for each behavior e Go to the Procedures tab e Rewrite the go procedure as follows EO go move turtles gat grass reproduce check death regrow grass end e Add the procedures for reproduce check death and regrow grass as shown below to reproduce ask turtles if energy gt 50 set energy energy 50 Tutorial 3 Procedures 59 NetLogo 4 0 User Manual hatch 1 set energy 50 end to ch
418. this program e setup and go are user defined commands e clear all crt create turtles ask 1t left turn and rt right turn are all primitive commands e random and turtles are primitive reporters random takes a single number as an input and reports a random integer that is less than the input in this case between 0 and 9 turtles reports the agentset consisting of all the turtles We ll explain about agentsets later setup and go can be called by other procedures or by buttons Many NetLogo models have a once button that calls a procedure called setup and a forever button that calls a procedure called go In NetLogo you must specify which agents turtles patches links or the observer are to run each command If you don t specify the code is run by the observer In the code above the observer uses ask to make the set of all turtles run the commands between the square brackets clear all and crt can only be run by the observer fd on the other hand can only be run by turtles Some other commands and reporters such as set can be run by different agent types Here are some more advanced features you can take advantage of when defining your own procedures Procedures with inputs Your own procedures can take inputs just like primitives do To create a procedure that accepts inputs include a list of input names in square brackets after the procedure name For example to draw polygon num sides len p
419. tion by selecting Force Quit in the Apple menu On Windows press Ctrl Alt Delete to open the Task Manager select HubNet Client and press End Task My computer went to sleep while running a HubNet activity When woke the computer up got an error and HubNet wouldn t work anymore The HubNet server may stop working if the computer goes to sleep If this happens quit the NetLogo application and start over Change the settings on your computer so it won t sleep again My problem is not addressed on this page Please send us an email at feedback ccl northwestern edu Known Limitations If HubNet malfunctions please send us an email at bugs ccl northwestern edu Please note that e HubNet has not yet been extensively tested with large numbers of clients i e more than about 25 Unexpected results may occur with more clients 166 HubNet Guide NetLogo 4 0 User Manual e Out of memory conditions are not handled gracefully e Sending large amounts of plotting messages to the clients can take a long time e NetLogo does not handle malicious clients in a robust manner in other words it is likely vulnerable to denial of service type attacks e Performance does not degrade gracefully over slow or unreliable network connections e If you are on a wireless network or sub LAN the IP address in the HubNet Control Center is not always the entire IP address of the server e Computer HubNet has only been tested on LANs and not on dial up
420. tion of setup refers to two new procedures To define setup patches add this to setup patches ask patches set pcolor green end The setup patches procedure sets the color of every patch to green to start with A turtle s color variable is color a patch s is pcolor The only part remaining in our new setup that is still undefined is setup turt les e Add this procedure too to setup turtles create turtles 100 ask turtles setxy random xcor random ycor end Did you notice that the new setup turt les procedure has most of the same commands as the old setup procedure 52 Tutorial 3 Procedures NetLogo 4 0 User Manual e Switch back to the Interface tab e Press the setup button Voila A lush NetLogo landscape complete with turtles and green patches appears After seeing the new setup procedure work a few times you may find it helpful to read through the procedure definitions again Turtle variables So we have some turtles running around on a landscape but they aren t doing anything with it Let s add some interaction between the turtles and the patches We ll make the turtles eat grass the green patches reproduce and die The grass will gradually grow back after it is eaten We ll need a way of controlling when a turtle reproduces and dies We ll determine that by keeping track of how much energy each turtle has To do that we need to add a new turtle variable You ve already seen bui
421. tive 1f not can move distance rt 180 can move merely returns true if the position distance in front of the turtle is inside the NetLogo world false otherwise In this case if the turtle is at the edge of the world it simple goes back the way it came You can also use patch ahead 1 nobody in place of can move If you need to do something smarter that simply turning around it may be useful to use patch at with dx and dy if patch at dx 0 nobody set heading heading 124 Programming Guide NetLogo 4 0 User Manual if patch at 0 dy nobody set heading 180 heading This tests whether the turtle is hitting a horizontal or vertical wall and bounces off that wall In some models if a turtle can t move forward it simply dies exits the system like in Conductor or Mousetraps if not can move distance die If you are moving turtles using setxy rather than forward you should test to make sure the patch you are about to move to exists since setxy throws a runtime error if it is given coordinates outside the world This is a common situation when the model is simulating an infinite plane and turtles outside the view should simply be hidden let new x new value of xcor let new y new value of ycor ifelse patch at new x xcor new y ycor nobody hide turtle setxy new x new y show turtle Several models in the Models Library use this technique Gravitation N Bodies and Electrost
422. tle If the turtle dies the perspective resets to the default See also reset perspective watch follow subject ride me NetLogo Dictionary 317 NetLogo 4 0 User Manual ride me Asks the observer to ride the calling turtle See also ride right rt right number The turtle turns right by number degrees If number is negative it turns left round round number Reports the integer nearest to number If the decimal portion of number is exactly 5 the number is rounded in the positive direction Note that rounding in the positive direction is not always how rounding is done in other software programs In particular it does not match the behavior of StarLogoT which always rounded numbers ending in 0 5 to the nearest even integer The rationale for this behavior is that it matches how turtle coordinates relate to patch coordinates in NetLogo For example if a turtle s xcor is 4 5 then it is on the boundary between a patch whose pxcor is 4 and a patch whose pxcor is 5 but the turtle must be considered to be in one patch or the other so the turtle is considered to be in the patch whose pxcor is 4 because we round towards the positive numbers show round 4 2 gt 4 show round 4 5 gt 5 show round 4 5 gt 4 run run string This agent interprets the given string as a sequence of one or more NetLogo commands and runs them The code runs in the agent s current context which means it has access
423. ture version but to troubleshoot it we need help from users 220 FAQ Frequently Asked Questions NetLogo 4 0 User Manual Can have multiple versions of NetLogo installed at the same time Yes When you install NetLogo the folder that is created contains has the version number in its name so multiple versions can coexist On Windows systems whichever version you installed last will be the version that opens when you double click a model file in Windows Explorer On Macs you can control what version opens via Get Info in the Finder I m on a UNIX system and can t untar the download Why Some of the files in the tarball have very long pathnames too long for the standard tar format You must use the GNU version of tar instead or another program which understands the GNU tar extensions On some systems the GNU version of tar is available under the name gnutar You can find out if you are already using the GNU version by typing tar version and seeing if the output says tar GNU tar How do install NetLogo unattended It depends on which platform you are using e Linux Untar NetLogo into the appropriate place Optionally add your own shell script to cd into the NetLogo directory and call java on the NetLogo jar For example assuming you copied the netlogo distribution into opt net logo bin bash cd opt netlogo usr local sun jdk1 5 0 bin java jar NetLogo jar Mac Copy the NetLogo directory from the
424. uations rather than hanging NetLogo if endless recursion occurs NetLogo now reports the error instead of bombing while startup commands run the user is now prevented from interacting with the model plotting is now supported when running headless use export plot or export world to save plotted data for later perusal in the 3D view turtle shapes now wrap around the edges if the world has wrapping enabled upgraded JOGL fixing 3D view bugs for some users applets can now find files associated with the model even if the model file is in a different location than the HTML file in the system dynamics modeler rate connectors can now be repositioned the system dynamics modeler now shows the location of syntax errors in the system dynamics modeler you can now control which plot is used using set current plot and which stocks are plotted is controlled by plot pen exists default maximum Java heap size raised to one gigabyte headless mode now works with IBM s Java the GoGo extension is now easier to use no separate installation steps required new checkbox allows you to turn off the world wire frame in the 3D view e extensions API changes the extensions API now has a version number so extensions can be used with different NetLogo versions as long as the API version number hasn t changed instead of being just a jar an extension is now a directory containing a jar so that the directory can contain other supporting files there is n
425. ue ask turtle 1 show link neighbor turtle 0 7 prints true netlogo applet netlogo applet Reports true if the model is running as an applet netlogo version netlogo version Reports a string containing the version number of the NetLogo you are running show netlogo version gt 4 0 new seed new seed Reports a number suitable for seeding the random number generator 298 NetLogo Dictionary NetLogo 4 0 User Manual The numbers reported by new seed are based on the current date and time in milliseconds and lie in NetLogo s allowed range of integers 9007199254740992 to 9007199254740992 new seed never reports the same number twice in succession This is accomplished by waiting a millisecond if the seed for the current millisecond was already used See also_random seed no display no display Turns off all updates to the current view until the display command is issued This has two major uses One you can control when the user sees view updates You might want to change lots of things on the view behind the user s back so to speak then make them visible to the user all at once Two your model will run faster when view updating is off so if you re in a hurry this command will let you get results faster Note that normally you don t need to use no display for this since you can also use the on off switch in view control strip to freeze the view Note that display and no display operate independe
426. umbers 1 to 8 Value ranges between 0 1023 1023 is returned when there is no sensor attached to the port highest resistance or when the sensor is an open state Zero is returned when the sensor is short circuited no resistance Examples print gogo sensor 1 7 prints the value of sensor 1 foreach 12345678 print word Sensor gogo sensor 7 prints the value of all sensors if gogo sensor 1 lt 500 ask turtles fd 10 7 will move all turtles 10 steps forward if sensor 1 s value is less than 500 loop if gogo sensor 1 lt 500 ask turtles fd 10 1 7 will continuously check sensor 1 s value and 77 move all turtles 10 steps forward every time 7 that the sensor value is less than 500 gogo set output port power gogo set output port power power level Sets the power level of the active output ports power level is a number between O off and 7 full power The output ports effected by those command are determined by the gogo talk to output ports command Note that for many practical applications it is more efficient to use mechanical devices such as gears and pulleys to control the torque of motors Example gogo talk to motors a b cr nar gogo set motor power 4 7 will lower the power of all output ports by half of the full power GoGo Extension 209 NetLogo 4 0 User Manual 210 GoGo Extension Profiler Extension The Profiler Extension provides information which may help you make
427. up Most models including Wolf Sheep Predation have a once button called setup and a forever button called go Many models also have a once button called go once or step once which is like go except that it advances the model by one tick time step instead of over and over Using a once button like this lets you watch the progress of the model more closely Stopping a forever button is the normal way to stop a model It s safe to pause a model by stopping a forever button then make it go on by pressing the button again You can also stop a model with the Halt item on the Tools menu but you should only do this if the model is stuck for some reason Using Halt may interrupt the model in the middle of an action and as the result the model could get confused e If you like experiment with the setup and go buttons in the Wolf Sheep Predation model Do you ever get different results if you run the model several times with the same settings 28 Tutorial 1 Models NetLogo 4 0 User Manual Controlling speed Speed Slider The speed slider allows you to control the speed of a model that is the speed at which turtles move patches change color and so on _ _ _ normal speed When you move the slider to the left the model slows down so there are longer pauses between each tick time step That makes it easier to see what is happening You might even slow the model down so far as to see exactly what a single t
428. ur model using the mouse in other ways too Another possibility is to use a special drawing model such as the Drawing Tool model by James Steiner which is available from_http ccl northwestern edu netlogo models community FAQ Frequently Asked Questions 225 NetLogo 4 0 User Manual A third possibility is to create an image in another program and import it See the answer to_Can import a graphic into NetLogo How big can my model be How many turtles patches procedures buttons and so on can my model contain We have tested NetLogo with models that use hundreds of megabytes of RAM and they work fine We haven t tested models that use gigabytes of RAM though Theoretically it should work but you might hit some limits that are inherent in the underlying Java VM and or operating system either designed in limits or bugs The NetLogo engine has no fixed limits on size On Macintosh and Windows operating systems though by default NetLogo ships with a one gigabyte ceiling on how much total RAM it can use On other operating systems the ceiling is determined by your Java VM Here s how to raise the limit if you need to e Windows Edit this section of the NetLogo lax file in the NetLogo folder LAX NL JAVA OPTION JAVA HEAP SIZE MAX allow the heap to get huge lax nl java option java heap size max 536870912 Note this might not help on some Windows 98 or Windows ME systems Macintosh Edit the Conte
429. ure for each call Here is example output Sorted by Exclusive Time 212 Profiler Extension Name CAL TH CAL ME REPO RI Sorted by Inclusive Time Name CAL TH CAL ME REPO RI Sorted by Number of Calls Name CAL THI EM Profiler Extension NetLogo 4 0 User Manual Cal Call Cal Excl T ms 19 476 6 413 O 147 Excl calls 1 498 0 493 0 014 Excl T ms 19 476 6 413 0 177 Excl calls 1 498 0 493 0 014 ls Incl T ms 13 26 066 13 6 413 13 0 177 ls Incl T ms 13 26 066 13 6 413 13 0 177 ls Incl T ms 13 26 066 Excl T ms 19 476 Excl calls 1 498 213 NetLogo 4 0 User Manual 214 Profiler Extension FAQ Frequently Asked Questions Feedback from users is very valuable to us in designing and improving NetLogo We d like to hear from you Please send comments suggestions and questions to feedback ccl northwestern edu and bug reports to bugs ccl northwestern edu Questions General e Why is it called NetLogo e How do cite NetLogo in an academic publication e How do cite a model from the Models Library in an academic publication e Where and when was NetLogo created e What programming language was NetLogo written in e What s the difference between StarLogo MacStarLogo StarLogoT and NetLogo e What license is NetLogo released under
430. urtle is doing When you move the speed slider to the right of the center the model will speed up NetLogo will start skipping frames that is it won t update the view at the end of every tick only some ticks Showing the state of the world takes time so showing it less often means the model progresses faster Note that if you push the speed slider well to the right the view update may update so frequently that the model appears to have slowed down It hasn t as you can see by watching the tick counter Only the frequency of updates has lessened Adjusting Settings Sliders and Switches The settings within a model give you an opportunity to work out different scenarios or hypotheses Altering the settings and then running the model to see how it reacts to those changes can give you a deeper understanding of the phenomena being modeled Switches and sliders give you access to a model s settings Here are the switches and sliders in Wolf Sheep Predation setup go i i Grass settings i Sheep settings Wolf settings Let s experiment with their effect on the behavior of the model Tutorial 1 Models 29 NetLogo 4 0 User Manual e Open Wolf Sheep Predation if it s not open already e Press setup and go and let the model run for about a 100 time ticks Note there is a readout of the number of ticks right above the plot e Stop the model by pressing the go button What happened to the she
431. utcome is when you start the model over again How to start over 1 If the go button is pressed black then the model is still running Press the button again to stop it 2 Adjust the tolerance slider to a new value by dragging its red handle 3 Press the setup button to reset the model 4 Press the go button to start the model running again Challenge As the host of the party you would like to see both men and women mingling within the groups Adjust the tolerance slider on the side of the view to get all groups to be mixed as an end result To make sure all groups of 10 have both sexes at what level should we set the tolerance Test your predictions on the model Can you see any other factors or variables that might affect the male to female ratio within each group Make predictions and test your ideas within this model Feel free to manipulate more than one variable at a time As you are testing your hypotheses you will notice that patterns are emerging from the data For example if you keep the number of people at the party constant but gradually increase the Sample Model Party 25 NetLogo 4 0 User Manual tolerance level more mixed groups appear How high does the tolerance value have to be before you get mixed groups What percent tolerance tends to produce what percentage of mixing Thinking With Models Using NetLogo to model situations like this party scenario allows you to experiment with a sy
432. ways see the whole world around it 4 1 2 A0 2 a ye 1 2 2 2 31 1 0 1 P 1 1 2 1 1 0 0 0 1 0 co o 1 1 0 1 1 1 2 1 2 1 Whereas in a box or cylinder the world has edges so the areas past those edges show up in the view as gray 1 1 0 1 1 0 0 0 1 1 MQ 1 1 1 Code Example Termites Perspective Demo torus Ants Perspective Demo box Instead of 3 0 s settings that only control the appearance of wrapping in the view NetLogo 3 1 has settings that control whether the world actually wraps or not that is whether opposite edges are in fact connected These new wrapping settings determine the world topology that is whether the world is a torus box or cylinder This affects the behavior and not just the visual appearance of the model 122 Programming Guide NetLogo 4 0 User Manual In the past model authors were required to write extra code to simulate a box world with the aid of special no wrap primitives No wrap versions were provided for distance xy in radius in cone face xy and towards xy In 3 1 the special no wrap versions are no longer necessary Instead the topology controls whether the primitives wrap or not They always use the shortest path allowed by the topology For example the distance from the center of the patches in the bottom right corner min pxcor min pycor and the upper left corner max pxcor max pycor will be as follow
433. ways used in conjunction with each other See to report for a discussion of how to use them reset perspective rp reset perspective The observer stops watching following or riding any turtles or patches If it wasn t watching following or riding anybody nothing happens In the 3D view the observer also returns to its default position above the origin looking straight down See also follow ride watch reset ticks reset ticks gt Resets the tick counter to zero See also tick ticks tick advance 316 NetLogo Dictionary NetLogo 4 0 User Manual reset timer reset timer Resets the timer to zero seconds See also timer Note that the timer is different from the tick counter The timer measures elapsed real time in seconds the tick counter measures elapsed model time in ticks reverse reverse list reverse string Reports a reversed copy of the given list or string show mylist 5 mylist is 2 7 4 Bob set mylist reverse mylist 7 mylist now is Bob 4 7 2 show reverse live gt evil rgb rgb red green blue Reports a RGB list when three numbers describing an RGB color The numbers are range checked to be between 0 and 255 See also_hsb ride ride turtle o Set the perspective to turtle Every time turtle moves the observer also moves Thus in the 2D View the turtle will stay at the center of the view In the 3D view it is as if looking through the eyes of the tur
434. wever you should notice that it does not callclear al1 In this model and in the great majority of HubNet activities in the Models Library we have a breed of turtles that represent the currently logged in clients In this case we ve called this breed students Whenever a client logs in we create a student and record any information we might need later about that client in a turtle variable Since we don t want to require users to log out and log back in every time we setup the activity we don t want to kill all the turtles instead we want to set all the variables back to initial values and notify the clients of any changes we make more on that later Receiving messages from clients During the activity you will be transferring data between the HubNet clients and the server Most HubNet activities will call a procedure in the go loop that checks for new messages from clients in this case it s called listen clients to listen clients while hubnet message waiting hubnet fetch messag ifelse hubnet enter message create new student ifelse hubnet exit message remove student execute command hubnet message tag end As long as there are messages in the queue this loop fetches each message one at a time hubnet fetch message makes the next message in the queue the current message and sets the reporters hubnet message source hubnet message tag and hubnet message to the appropriate values The clients send
435. white and press return What does the View look like now Do you notice any differences between these two commands and the observer commands from earlier Tutorial 2 Commands 39 NetLogo 4 0 User Manual The observer oversees the world and therefore can give a command to the patches or turtles using ask Like in the first example observer gt ask patches set pcolor yellow the observer has to ask the patches to set their pcolor to yellow But when a command is directly given to a group of agents like in the second example patches gt set pcolor white you only have to give the command itself e Press setup What happened Why did the View revert back to the old version with the black background and white road Upon pressing the setup button the model will reconfigure itself back to the settings outlined in the Procedures tab The Command Center is not often used to permanently change the model It is most often used as a tool to customize current models and allows for you to manipulate the NetLogo world to further answer those What if questions that pop up as you are investigating the models The Procedures tab is explained in the next tutorial and in the_Programming Guide Now that we have familiarized ourselves with the Command Center let s look at some more details about how colors work in NetLogo Working With Colors You may have noticed in the previous section that we used two different words for changin
436. ws researchers to record students actions for later analysis 4 built in tick counter for keeping track of model time see language changes below new view update system there are now two view update modes tick based and continuous continuous is the default when you start up NetLogo tick based is the default for most models in the Models Library continuous update mode is useful for non tick based models like Termites but may also be useful during debugging 0 tick based updates are faster for most models and avoid displaying intermediate state buttons no longer have a force view update checkbox most models should use tick and or display instead improved speed slider 0 you can now use the slider to fast forward a model by updating the view less often 0 in tick based update mode going slower pauses between ticks rather than showing intermediate states 0 in continuous update mode going slower shows intermediate states you can even go so slow you can watch agents move one at a time new input boxes in Interface tab permit entering text numbers colors or NetLogo code as model parameters arrays and hash tables are now supported via extensions see Arrays amp Tables section of User Manual new profiler extension lets you measure the running times of your procedures new experimental includes keyword allows splitting model code into multiple files color variables can now contain either a NetLogo color or an RGB color
437. xcor random pycor random pxcor random pycor Reports a random integer ranging from min pxcor or y to max pxcor or y inclusive ask turtles 7 move each turtle to the center of a random patch setxy random pxcor random pycor See also random xcor random ycor random seed random seed number Sets the seed of the pseudo random number generator to the integer part of number The seed may be any integer in the range supported by NetLogo 9007199254740992 to 9007199254740992 See the Random Numbers section of the Programming Guide for more details random seed 47823 show random 100 gt 57 show random 100 gt 91 andom seed 47823 how random 100 gt 57 show random 100 gt 91 I na K 312 NetLogo Dictionary NetLogo 4 0 User Manual random xcor random ycor random xcor random ycor Reports a random floating point number from the allowable range of turtle coordinates along the given axis x or y Turtle coordinates range from min pxcor 0 5 inclusive to max pxcor 0 5 exclusive horizontally vertically substitute y for x ask turtles 77 move each turtle to a random point setxy random xcor random ycor See also_random pxcor random pycor read from string read from string string Interprets the given string as if it had been typed in the Command Center and reports the resulting value The result may be a number list string or boolean value or the spec
438. xperiment that takes only a String argument and an argument to specify the output format is used to pass the XML for the experiment setup directly All of these methods take a PrintWriter as a destination for the results If you just want to send them to standard output you can pass new java io PrintWriter System out The BehaviorSpace Guide explains how to specify experiment setups in XML The NetLogo API Specification contains further details on the HeadlessWorkspace class and its methods Other Options When your program controls NetLogo using the App class the entire NetLogo application is present including tabs menubar and so forth This arrangement is suitable for controlling or scripting a NetLogo model but not ideal for embedding a NetLogo model in a larger application We also have a separate similar API which allows embedding only parts of NetLogo such as only the tabs not the whole window or only the contents of the Interface tab At present this additional API is not documented If you are interested in using it please contact us at feedback ccl northwestern edu Conclusion Don t forget to consult the NetLogo API Specification for full details on these classes and methods As mentioned before the controlling facility is considered experimental This initial API doesn t necessarily include everything you might expect Some facilities exist but are not yet documented So if you don t see the capability you want
439. y Java API calls Conclusion Don t forget to consult the NetLogo API Specification for full details on these classes interfaces and methods Note that there is no way for the modeler to get a list of commands and reporters provided by an extension so it s important that you provide adequate documentation The extensions facility is not yet complete The API doesn t include everything you might expect to be present Some facilities exist but are not yet documented If you don t see a capability you want please let us know Do not hesitate to contact us at feedback ccl northwestern edu with questions as we may be able to find a workaround or provide additional guidance where our documentation is thin Hearing from users of this API will also allow us to appropriately focus our efforts for future releases We are committed to making NetLogo flexible and extensible and we very much welcome your feedback Extensions Guide 193 NetLogo 4 0 User Manual 194 Extensions Guide Array and Table Extensions These extensions add two new data structures to NetLogo arrays and hash tables When to use In general anything you can do with an array or table you could also just use a list for But you may want to consider using an array or table instead for speed reasons All three data structures list array and table have different performance characteristics so you may be able to make your model run faster by selecting the appropriate
440. y arranged in a circle layout with a user defined radius and the other nodes will converge into place this of course means that you may have to run it several times before the layout is stable layout spring and __layout magspring are quite similar and are useful for many kinds of networks The drawback is that they are relatively slow since they take many iterations to converge In both layouts the links act as springs that pull the nodes they connect toward each other and the nodes repel each other In the magnetic spring there is also a magnetic field pulling the nodes in a compass direction you choose The strength of all of these forces are controlled by inputs to the primitives These inputs will always have a value between 0 and 1 keep in mind that very small changes can still affect the appearance of the network The springs also have a length in patch units however because of all the forces involved the nodes will not end up exactly that distance from each other The magnetic spring layout also has a boolean input bidirectional which indicates whether the springs should push in both directions parallel to the magnetic field if it is true the networks will be more evenly spaced Programming Guide 127 NetLogo 4 0 User Manual Code Examples Network Example Network Import Example Giant Component Small Worlds Preferential Attachment Ask Concurrent In previous versions of NetLogo ask was concurrent by default As of NetLo
441. y letting them see things they aren t supposed to see which may be misleading 3 Increased speed Updating the view takes time so if one update per tick is enough then enforcing than there is only one update per tick will make your model faster 4 Instead of having a force view update checkbox in every button like in NetLogo 3 1 we only need one choice which applies to the entire model 5 Using the speed slider to slow down a model now just inserts pauses between ticks So with tick based updates setup buttons are no longer affected by the speed slider This was a real annoyance with the old speed slider The annoyance persists for models that use continuous updates though As mentioned above most models in our Models Library now uses tick based updates Even for models that would normally be set to tick based updates it may be useful to switch to continuous updates temporarily for debugging purposes Seeing what s going on within a tick instead of only seeing the end result of a tick could help with troubleshooting If you switch your model to use tick based updates you ll also need to add the ti ck command to your code otherwise the view won t update Note that the view still always updates when a button pops up or a command entered in the command center finishes though So it s not like the view will just stay frozen indefinitely How to make a model use ticks and tick based updates Here are the steps to follow to conver
442. y ones that use pseudo random numbers Many other operations also make random choices For example agentsets are always in random order one of and n of choose agents randomly the sprout command creates turtles with random colors and headings and the downhill reporter chooses a random patch when there s a tie All of these random choices are governed by the random seed as well so model runs can be reproducible In addition to the uniformly distributed random integers and floating point numbers generated by random and random float NetLogo also offers several other random distributions See the dictionary entries for random normal random poisson random exponential and random gamma Auxiliary generator Code run by buttons or from the command center uses the main random number generator Code in monitors uses an auxiliary random generator so even ifa monitor does a calculation that uses random numbers the outcome of the model is not affected The same is true of code in sliders Local randomness You may want to explicitly specify that a section of code does not affect the state of the main random generator so the outcome of the model is not affected The with local randomness command is provided for this purpose See its entry in the NetLogo Dictionary for more information Turtle shapes In NetLogo turtle shapes are vector shapes They are built up from basic geometric shapes squares circles and lines rather than a grid of pix
443. ycor Just like in the standard mathematical coordinate plane pxcor increases as you move to the right and pycor increases as you move up The total number of patches is determined by the settings min pxcor max pxcor min pycor and max pycor When NetLogo starts up min pxcor max pxcor min pycor and max pycor are 16 16 16 and 16 respectively This means that pxcor and pycor both range from 16 to 16 so there are 33 times 33 or 1089 patches total You can change the number of patches with the Settings button Turtles have coordinates too xcor and ycor A patch s coordinates are always integers but a turtle s coordinates can have decimals This means that a turtle can be positioned at any point within its patch it doesn t have to be in the center of the patch Links do not have coordinates instead they have two endpoints each a turtle Links appear between the two endpoints along the shortest path possible even if that means wrapping around the world The way the world of patches is connected can change By default the world is a torus which means it isn t bounded but wraps so when a turtle moves past the edge of the world it disappears and reappears on the opposite edge and every patch has the same number of neighbor patches if you re a patch on the edge of the world some of your neighbors are on the opposite edge However you can change the wrap settings with the Settings button If wrapping is not allowed in a g

NetLogo 4.0 User Manual - scstevenson

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