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NetLogo 3.0 User Manual

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1. ExtensionException r reporter takes an argument we also implement Syntax getSyntax Here s the implementation of our reporter in a file called IntegerList java import o public c LIE publ publ Notice rg nlogo api lass IntegerList extends DefaultReporter ake one number as input report a list ic Syntax getSyntax return Syntax reporterSyntax new int Syntax TYPE_NUMBER Syntax TYPE_LIST y ic Object report Argument args Context context throws ExtensionException create a NetLogo list for the result LogoList list new LogoList use typesafe helper method from org nlogo api Argument to access argument int n args 0 getIntegerValue if n lt 0 signals a NetLogo runtime error to the modeler throw new ExtensionException input must be positive populate the list for int i 1 i lt n itt list add new Integer i return list e To access arguments use org nlogo api Argument s typesafe helper methods such Extensions Guide 131 NetLogo 3 0 User Manual as getIntegerValue 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 implement void perform 2 Write a ClassManager Each extension must include in addition
2. Mathematical primitives log max mean median min mod modes new seed pi precision random random exponential random float random gamma random int or float random normal random poisson random seed remainder round sin sqrt standard deviation subtract headings sum tan variance Plotting primitives autoplot auto plot off auto plot on clear all plots clear plot create temporary plot pen export plot export all plots histogram from histogram list plot plot name plot pen down ppd plot pen reset plot pen up ppu _plot x max plot x min plot y max plot y min plotxy pod ppu 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 Movie primitives movie cancel movie close movie grab view movie grab interface movie set frame rate movie start movie status System primitives netlogo version Built In Variables Turtles breed color heading hidden label label color pen down shape size who xcor ycor Patches pcolor plabel plabel color pxcor pycor Other 2 Keywords breeds end globals patches own to to report turtles own Primitives Dictionary 169 NetLogo 3 0 User Manual Constants Mathematical Constants e 2 718281828459045 pi 3 141592653589793 Boolean Constants false true Color Constants black 0 0 gray 5 0 white 9 9 red 15 0 orange 25 0 brown 35 0 yellow 45 0 green 5
3. Mirror plots on clients experimental Y Broadcast serv dress Debug Kick Local 11 35 27 Craig joined from 129 105 107 236 51949 11 35 38 Esther joined from 129 105 107 236 51952 0 11 35 49 Andrei joined from 129 105 107 236 51955 a v 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 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 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 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 name an
4. 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 Primitives Dictionary 189 NetLogo 3 0 User Manual file open myfile data 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 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 file at end to determine if you are at the end of the file file open myfile txt print file read characters 8 Current line in file is Hello World gt Hello Wo 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 re
5. Display name Action key Force view update after each run Checking this box produces smoother animation but may make the button run more slowly FP 4 Press OK to dismiss the dialog box Tutorial 3 Procedures 45 NetLogo 3 0 User Manual Now you have a button called setup It will execute the procedure setup when pressed which once we define it will do just that set up the NetLogo world At this point both the new button and the Interface tab have turned red That s because there is no procedure called setup If you want to see the actual error message click on the button interface Information Procedures pa Button Slider EN Switch E Chooser ES Mon V 4 II gt 33h Ei 30 setup Now switch to the Procedures Tab and create the setup procedure shown below Notice that the lines are indented different amounts A lot of people find it very helpful to indent their code in a way at least similar to how it s done here It helps them keep track of where they re at inside of a procedure and makes what they write easier for others to read as well Interface Information 2 Find A Check Procedures to setup ca crt 100 ask turtles fd random screen edge x 7 end One line at a time to setup begins defining a procedure named setup ca is short for clear all you can also spell it out if you want This command will blank out the screen
6. 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 temporary 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 0 and plots in line mode Commands are available to change all of these settings see the Plotting section of the Primitives Dictionary Conclusion Not every aspect of NetLogo s plotting system has been explained here See the Plotting section of the Primitives Dictionary for information on additional commands and reporters related to plotting 96 Programming Guide NetLogo 3 0 User Manual Many of the Sample Models in the Models Library i
7. List String Math Plotting Movie System HubNet Special Variables Keywords _Constants Categories of Primitives This is an approximate grouping Remember that a turtle related primitive might still be called by patches or observers and vice versa To see which agent turtles patches observer can actually run each command consult each individual entry in the dictionary Turtle related back bk BREED at BREED here BREED on clear turtles ct create BREED create custom BREED create custom turtles cct create turtles crt die distance distance nowrap distancexy distancexy nowrap downhill downhill4 dx dy face face nowrap facexy facexy nowrap forward fd hatch hatch BREED hideturtle ht home inspect is turtle jump left It myself no label nobody of other turtles here other BREED here patch ahead patch at heading and distance patch here patch left and ahead patch right and ahead pen down pd pen erase pe pen up pu right rt self set default shape setxy shapes showturile st sprout sprout BREED stamp subject subtract headings towards towards nowrap towardsxy towardsxy nowrap turtle turtles turtles at turtles from turtles here turtles on turtles own uphill value from Patch related primitives clear patches cp diffuse diffuse4 distance distance nowrap distancexy distancexy nowrap import pcolors inspect is patch myself neighbors neighbors4 no label nobod
8. World amp View Screen edge Y 25 of patches vertically is twice this number plus one Patch size pixels 9 0 Font size of turtle and patch labels 14 Y Turtle shapes Y View wraps horizontally M View wraps vertically wrapping options only affect views not behavior of model v Smooth edges slower Cancel Apply Cox gt only affects 3D view What are the current settings for Screen Edge X Screen Edge Y 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 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 Edit 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 Tutorial 1 Models 31 NetLogo 3 0 User Manual 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 T
9. Writing Extensions We assume you have experience programming in Java Summary A NetLogo extension is a JAR that contains e one or more classes that implementation org nlogo api Primitive e a main class that implements org nlogo api ClassManager and e a NetLogo extension manifest file The manifest file 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 Version the version of NetLogo for which this JAR is intended If a user opens the extension with a different version of NetLogo a warning message is issued 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 1 through n Of course you could easily do this just in NetLogo it s only an example 130 Extensions Guide 1 Write NetLogo 3 0 User Manual primitives 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 Since ou
10. button in the control strip 000 World amp View Screen edge X 17 of patches horizontally is twice this number plus one Screen edge Y 17 of patches vertically is twice this number plus one Patch size pixels 12 0 Font size of turtle and patch labels 10 Y Turtle shapes Y Views wrap horizontally Y Views wrap vertically wrapping options only affect views not behavior of model Y Smooth edges slower only affects 3D view To change the size of the 2D View adjust the Patch Size setting which is 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 To change the number of patches alter the Screen Edge X and Screen Edge Y settings Note that changing the numbers of patches requires rebuilding the NetLogo world you will lose all turtles and the values of all variables The Turtle Shapes checkbox performs the same function as the shapes button in the control strip discussed above The Views wrap horizontally vertically checkboxes indicate whether you would like the world to appear as a torus or not This includes wrapping shapes around the world and wrapping turtles and patches in follow and ride modes Note that this only affects the the visual appearance not the behavior of the model The Smoo
11. variance variance list Reports the sample variance of a ist 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 W wait Primitives Dictionary 251 NetLogo 3 0 User Manual wait number Wait the given number of seconds You can use floating point numbers to 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 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 k 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 repeat 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 who who k This is a built in turtle variable It holds the turtle s id number an integer greater than or equal to zero You cannot set t
12. 10 12 observer 1 0E 12 You can also use scientific notation yourself in NetLogo code O gt show 3 0E6 observer 3000000 0 O gt show 3 0E7 observer 3 0E7 O gt show 8 0E 3 observer 0 0080 O gt show 8 0E 4 observer 8 0E 4 These examples show that numbers are displayed using scientific notation if the exponent is less than 3 or greater than 6 When entering a number using scientific notation you must include the decimal point For example 1E8 will not be accepted Instead you must write 1 0E8 or 1 E8 O gt show 1 0E8 observer 1 0E8 O gt show 1 E8 observer 1 0E8 O gt show 1E8 ERROR Illegal number format Programming Guide 91 NetLogo 3 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 O gt show 4 5e10 observer 4 5E10 Floating point accuracy When using floating point numbers you should be aware that due to the limitations of the binary representation for floating point numbers you may get answers that are slightly inaccurate For example O gt show 0 1 0 1 0 1 observer 0 30000000000000004 O gt show cos 90 observer 6 123233995736766E 17 This is an inherent issue with floating point arithmetic it occurs in all programming languages that support floating point If you are dealing with fixed precision quantities for example dollars and cents a common te
13. NetLogo 3 0 User Manual NetLogo 3 0 User Manual Table of Contents What IS NETLOG Pia ii 1 ESTOS uri AA a o E ee da 1 COPyEON LIMA ION A Galea a hee 3 Third party licenses ia dead 3 What s NeW io aida 7 Version 3 0 September 14 2005D ccooooooooccccncccnonoooonnnnnnncnnnnnnnonnnnnnnnncrnnnnnnnnrnnnrrcnnnnnnnnnrnnnnnnnnnn 7 Version 2 1 December200 Aa ios 10 Versi n 2 0 2 AUgust2004 hercacooca tasar ed a a A E AREE a aa EREE oa 10 Version 2 0 December 2003F sanne aa aA e ate aaa dd 11 Version SKA VAEA OE y E E E E A A E E EA E 11 Version 1 2 March 2008 iia aia 11 Version July200 a LA dada neonates 11 MAN A NO 11 Systeni Requirements P P P ataxeascessseceuauaansvensatsne 13 System Requirements ApplicatiON oooocccccccnononocnccnonononnnonannnnnnnnnccconnnnnnnnnnnnncnnnnnnonnnnnnnnn 13 WING OWS execs even coves an dat A E a a 13 MacOSX rate A cee DO E AT A ad BD ds Bs el 13 MacOS 8 and Dri A A pro qa Do ta asa hats 13 Oth r plato NS las ratas 13 System Requirements Saved AppletS ccccoooooooccccccconoconononnccnnnoncncnnnnnnnnnnnnccnnnannnnnnnnnnnn 14 System Requirements 3D ViBW ccccooooococnconcccnonononnncncnnnnnnnnnnonnnnnnnnnrcnnnnnnnnnrnnnnnrcnnnnnnnnrnnnnnnn 14 Operatina SOMOS a 14 Graphics Cards aa 14 Euliscreen Mode suis sussa aa 15 LIBRAS OMMIGIS pecus E ES TO CANA 15 Removing an old JOG iaa 15 KNOWMISSUCS cuina naaa aaa dada 17 Known bugs all SYSteMS ee 17 Windows only DUS inc
14. 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 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 is a floating point number 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 to make the mouse draw in red if mouse down set pcolor of patch at mouse xcor mouse ycor red Primitives Dictionary 211 NetLogo 3 0 User Manual movie cancel movie cancel Cancels the current movie movie close movie cancel Stops the recording of the current movie 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 Must be called after movie start but before movie grab area See also movie status movie set frame rate movie start movie start filename C
15. Then inside of setup turtles instead of crt 100 you can type crt number How does using more or fewer turtles affect the success value displayed by the plot Third when all the turtles have found their local maxima wouldn t it be nice for the model to stop This requires a few lines of code e Add a global variable turtles moved to the globals list globals highest Maximum patch elevation lowest 77 minimum patch elevation turtles moved so we know when to stop the model e At the end of the go procedure add a test to see if any turtles have moved to go set turtles moved false move to local max do plots if not turtles moved stop end e In move to local max if a turtle moves set turtles moved to true to move to local max ask turtles set heading uphill elevation if elevation of patch ahead 1 gt elevation fd set turtles moved tru end Finally what rules can you think of that would help turtles escape from lower peaks and all get to the highest ones Try writing them Tutorial 3 Procedures 57 NetLogo 3 0 User Manual What s Next So now you have a nice framework for exploring this problem of hill climbing using all sorts of NetLogo modeling features buttons sliders monitors plots and the view You ve even written a quick procedure to give the turtles something to do And that s where this tutorial leaves off If you d like to look at some more documentati
16. e screen color bgcolor or setbg set the background color the same effect can be achieved by ask patches set pcolor blue e reverse lines e refresh mode Some logos allow the user to back up the movement of the turtle NetLogo does not track the movements of turtles e WINDOW and FENCE these are anlogous to infinite plane and bounded world topologies which we hope to add in a future version Features that work differently e When turtles are created in NetLogo the default mode is pen up instead of pen down e Clearing See clear all clear drawing Programming Guide 101 NetLogo 3 0 User Manual 102 Programming Guide Shapes Editor Guide The Shapes Editor allows you to create and save turtle designs NetLogo uses fully scalable and rotatable vector shapes which means it lets you create designs by combining basic geometric elements which can appear on screen in any size or orientation Getting Started To begin making shapes choose 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 shapes from a library or from another model Importing Shapes Every new model in NetLogo starts off containing a small core set of frequently used shapes Many more shapes are available by using the Import from library button This brings up a dialog where yo
17. note stari note stop note stop instrument stop music drums drums Reports a list of the names of the 47 drums for use with play drum instruments instruments Reports a list of the names of the 128 instruments for use with play note start note and stop note NetLogo Sound Extension 145 NetLogo 3 0 User Manual play drum play drum drum velocity Plays a drum play drum ACOUSTIC SNARE 64 play note play note instrument keynumber velocity duration Plays a note for a specified duration in seconds 7 play a trumpet at middle C for two seconds play note TRUMPET 60 64 2 start note start note instrument keynumber velocity Starts a note The note will continue until stop note stop instrument or stop music is called 7 play a violin at middle C start note VIOLIN 60 64 7 play a C major scale on a xylophone foreach 60 62 64 65 67 69 71 72 start note XYLOPHONE 65 wait 0 2 stop note XYLOPHONE stop note stop note instrument keynumber Stops a note 7 stop a violin note at middle C stop note VIOLIN 60 stop instrument stop instrument instrument Stops all notes of an instrument 7 stop all cello notes stop instrument CELLO 146 NetLogo Sound Extension stop music stop music Stops all notes Sound names Drums 35 Acoustic Bass Drum 36 Bass Drum 1 37 Side Stick 38 Acoustic Snare 39 Hand Clap 40 Electric Snare 4
18. set color black this turtle creates a new turtle 7 Of the sheep breed 194 Primitives Dictionary NetLogo 3 0 User Manual heading heading x 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 Example set heading 45 5 turtle is now facing northeast set heading heading 10 same effect as rt 10 hidden hidden x This is a built in turtle variable It holds a boolean true or false value indicating whether the turtle is currently hidden i e invisible You can set this variable to make a turtle disappear or reappear See also hideturtle showturtle Example set hidden not hidden 7 if turtle was showing it hides and if it was hiding it reappears hideturtle ht hideturtle The turtle makes itself invisible Note This command is equivalent to setting the turtle variable hidden to true See also_showturtle histogram from histogram from agentset reporter Draws a histogram showing the frequency distribution of the values reported when all agents in the agentset run the given reporter The heights of the bars in the histogram represent the numbers of Primitives Dictionary 195 NetLogo 3 0 User Manual agents with values in those ranges Before the histogram is drawn fi
19. Be ep Pa RR PR RAI RR 208 Mii A oi 208 MO A A E a Cabe Sao Da Doda da aa 209 MaX ONC 0 cueca cine A SRS ad a 209 NetLogo 3 0 User Manual Table of Contents Primitives Dictionary MOM a a gees 209 MA dat 209 member a A id A A DIA ML Re Be ASETE 209 naia EE A RS RR RI DA GR REPASSE A PRP UNR RR 210 MIN 0NO 0f Aisha Sesi iene stave natch ent asa od data 210 dl KR RR ch eee coe en SE ak i RR AR NPR meal RON 210 MODOS o aU A arado Sate PERSA RU DES CURADO E Casale E ER E gee RAS sad RS nu ATTE ea 211 MoUSe dOWI asno O 211 ano JU eis o S o ef APR ARARAS PRN ND RSRSRS SN DO ROD NES RR 211 mouSe xcor MOUSE YCOL iii eee eee terre eee eae ee ee eee nana a nana terene neaa 211 MOVIe Ccancel eta a Pb A Saad Ne A Rte Ae eee hh he A errr 212 O O 212 movie grab view Movie grab interface ccccccononononnccncccconononnoncnnnnnnnnnnnn ono nnnnnccnnnnnnnns 212 MOVIE Sel fraMO Aale sis soc dr iia 212 IMOVIE SLAM AEE e e de dd rasa a e 212 MOVIG S ALUS ssa Oral raias lala co Ria alas Alas Mietie chet shal lek tate tale i ola Ralado aa oh ta 213 MS aa 213 NL saci quado A RRA 213 N valtes A Ad RA O A O DO cado o DADA ae E o O A ia 213 neighbors neighbors4 eee reeneeeaeaane rena aaaa nana nana nanaranaranaranaaana 214 METOGO VErSlO Mss seit vies a de cd gera dor ede Haein sede dae ee ieee a aati 214 GWE S COG a A tn nam enn alan Set ERR Oy Meas ate eat a dna de 214 MO GISDIAY gt ccotcust cece ENE DS R
20. How many turtles patches procedures buttons and so on can my model CON Pasacalles 156 Can import an image into NetLogo ccooonoooccccccccononononncncnnnncccnnnnnnnnnnnnncccnnnnnnnnnnnnnnnnnns 156 Can import GIS data into Nello accio adas 157 My model runs slowly How can Speed it up eee 157 Livantto try HubNSE Can ursos aus a a A De 157 Can run a NetLogo model from the command line Can run it without a GUI 158 Can have more than one model open ata time eee 158 Can save the contents of the view Of the interface tab2 158 Can make a movie Of My Model occcccnonococcccccccnononononccnnnnnncoconnnnnnnnnnncccnnnnnnnnnnnnnnnnnnns 159 Does NetLogo take advantage of multiple processors 2 159 Can distribute NetLogo model runs across a cluster of computers 159 Can use screen edge x or screen edge y etc as the minimum or maximum of AAA A Pe IR Bs NE e a O Oe en 159 Can change the choices in a chooser on the fly2 eee 160 Can divide the code for my model up into several files 2 160 Progamming ii A A A de ad 160 How is the NetLogo language different from the StarLogoT language How do convert my StarLogoT model to NetLogo serena 160 How does the NetLogo language differ from other LOgoOS ccccconnnoconccccononccnnonananonoos 160 The NetLogo world is a torus that is the edges of the screen are connected to each
21. 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 you 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 DE
22. diffuse elevation 1 with repeat 5 diffuse elevation 1 The repeat command is another way for NetLogo to loop besides making a forever button which you already know how to do Repeat takes a number here 5 and some commands here the diffuse command and executes the commands that number of times here five times Try it out and look at the landscape i e press setup and see what you think Then press go and watch the turtles behavior Remember that the lighter the patch the greater the elevation Obviously fewer peaks make for an improvement in the turtles performance On the other hand maybe you feel like this is cheating the turtles really aren t doing any better it s just that their problem was made easier True enough If you call repeat with an even higher number 20 or so 54 Tutorial 3 Procedures NetLogo 3 0 User Manual you ll end up with only a handful of peaks as the values become more evenly distributed with every successive call Watch the values in the monitors In order to specify how smooth you want your world to be let s make it easier to try different values Maybe one time you ll want the turtles to try and solve a hard world and maybe another time you ll just want to look at an easy landscape So we ll make a global variable named smoothness Create a slider in the Interface tab and call it smoothness in the editing box The minimum can be 0 and the maximum can b
23. 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 Previews As you draw your shape you will also see it in five smaller sizes in the five preview areas found near 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 Elemen
24. include pxcor and 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 clock You can also define new turtle and patch variables using the turtles own and patches own keywords like this turtles own energy speed patches own friction 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 by 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 or set a different agent s variable you put of after the variable name and then specify which agent you mean Examples set color of turtle 5 red 5 turtle with ID number 5 turns red set pcolor of patch 2 3 green 7 patch with pxcor of 2 and pycor of 3 turns green ask turtles set pcolor of patch at 1 0 blue 7 every turtle turns the patch to its east blue ask patches with any turtles here set colo
25. initialize any variables you might have to O and remove all turiles Basically it wipes the slate clean for a new run of the project crt 100 will then create 100 turtles crt is short for create turtles If the turtles didn t move after this command is given each of these turtles would begin on the center patch at location 0 0 You would only see what looks like one turtle on the screen they d all be on top of each other lots of turtles can share the same patch Only the last turtle to arrive on the patch would be visible Each of these newly created turtles has its own color its own heading All of the turtles are evenly distributed around the circle ask turtles tells each turtle to execute independently the instructions inside the brackets Note that crt is not inside the brackets If the agent observer turtle or patch is not specified using ask the observer runs it Here the observer runs the ask but the turtles run the commands inside the ask 46 Tutorial 3 Procedures NetLogo 3 0 User Manual fd random screen edge x is a command that also uses reporters Reporters as opposed to commands are instructions that report a result Each turtle will first run the reporter random screen edge x which will report a random integer at least O but less than screen edge x the dimension from the center to the edge of the screen along the x axis It then takes this number and goes fd short for forward that number o
26. is patch agentset is string is turtle is turtle agentset is agent value is agentset value is boolean value is list value is number value is patch value is patch agentset value is string value is turtle value is turtle agentset value Reports true if value is of the given type false otherwise 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 suppose mylist is 2 4 6 8 10 204 Primitives Dictionary NetLogo 3 0 User Manual show item 2 mylist gt 6 show item 3 my shoe gt Won jump jump number Turtles move forward by number units all at once without the amount of time passing depending on the distance This command is useful for synchronizing turtle movements The command forward 15 takes 15 times longer to run than forward 1 but jump 15 runs in the same amount of time as forward 1 Note When turtles jump they do not step on any of the patches along their path L label label k This is a built in turtle variable It may hold a value of any type The turtle 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 s label See also no label label col
27. 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 BehaviorSpace Guide 113 NetLogo 3 0 User Manual The second line must be included exactly as shown In the first line you may specify a different encoding than us ascii such as UTF 8 but NetLogo doesn t support non ASCII characters in most situations so spe
28. way that your turtles always come to rest on patch centers A turtle is on a patch center when its xcor and ycor are multiples of 1 0 patch ahead 1 is reporting the same patch my turtle is already standing on Why See previous answer It s the same issue This might not be the meaning of ahead you were expecting With pat ch 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 162 FAQ Frequently Asked Questions NetLogo 3 0 User Manual 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 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 Does NetLogo have a command like StarLogo s grab command We don t have such a command You can use the without interruption primitive to arran
29. 0 User Manual 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 2 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 E 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 colors that can be used too Here s a chart that shows the whole NetLogo color space Tutorial 2 Commands 39 NetLogo 3 0 User Manual black 0 white 9 9 gray 5 8 9 9 9 red 15 19 199 orange 25 20 22 23 28 29 29 9 brown 35 30 32 33 e E 39 399 yellow 4
30. 0 User Manual list list value value2 list value valuen 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 5 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 locals locals Vax1 var2 NOTE This keyword should not be used in new models Please use the let command instead locals is included only for backwards compatibility with NetLogo version 2 0 and earlier It will not necessarily continue to be supported in future versions of NetLogo Locals is a keyword used to declare local variables in a procedure that is variables that are usable only within that procedure It must appear at the beginning of the procedure before any commands See also_let log log number base Reports the logarithm of number in base base show log 64 2 gt 6 See also In Primitives Dictionary 207 NetLogo 3 0 User Manual loop loop commands Runs the list of commands forever or until the current procedure 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 u
31. 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 122 Breath Noise 123 Seashore 124 Bird Tweet 125 Telephone Ring 126 Helicopter 127 Applause 128 Gunshot NetLogo Sound 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 General e Why is it called NetLogo e What programming language was NetLogo written in e How do cite NetLogo in an academic publication e How do cite a model from the Models Library in an academic publication e What license is NetLogo released under 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 What s the difference between StarLogo MacStarLogo StarLogoT and NetLogo e Has anyone built a model of lt x gt e Are NetLogo models runs scientifically reproducible 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 Will NetLogo and NetLogo 3D remain separate Downloading e The download form doesn t
32. Bob 7 set mylist remove duplicates mylist 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 3 banana gt banna repeat repeat number commands Runs commands number times pd repeat 36 fd 1 rt 10 5 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 string1 removed and the contents of string2 spliced in instead 230 Primitives Dictionary NetLogo 3 0 User Manual show replace item 2 2 7 4 5 15 gt 2 7 15 5 show replace item 1 sat lo gt slot 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 always used in conjunction with each other
33. Calculator HubNet you need e A computer with an attached projector This computer will run NetLogo and project the simulation for class viewing e A classroom set of Texas Instruments Tl 83 graphing calculators e The Tl Navigator calculator network from Texas Instruments NOTE Calculator HubNet works with a prototype version of the Tl Navigator system and is not yet compatible with the commercially available version To learn more about the TI Navigator system please visit the Texas Instruments website We are actively working in partnership with Texas Instruments on integrating the new Tl Navigator with Calculator HubNet We expect to release a new version in the near future For more information about Calculator HubNet please refer to the Participatory Simulations Guide which can be found on the Participatory Simulations Project web site Teacher workshops For information on upcoming workshops and NetLogo and HubNet use in the classroom please contact us at feedbackOccl 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 119 NetLogo 3 0 User Manual 120 HubNet Guide HubNet Authoring Guide This explains how to use NetLogo to modify the existing HubNet acti
34. EEEE 147 I ka IEN NR A E AED ELN E A ASE ESEN ANAN A dan dd 147 ASIN AS A EEIE EE EE E T AA 147 A ROA 149 DOWAIOACING atada aaa 149 ADDICTS i ari A E a Rda dine ea Dag 149 BE CE A ite 149 Programming seen deleite AE ao pa dera da ad la anda eras ice 149 Generalista meu Dn ps tallada 150 Why is tt Calle NOOO a ade 150 What programming language was NetLogo written in2 e 150 How do cite NetLogo in an academic publication eee 151 How do cite a model from the Models Library in an academic publication 151 What license is NetLogo released under Are there are any legal restrictions on use redistribution etc 2 resetar tacar tree area aresta anna 151 Is the source code to NetLogo available oooocccccnonocococnnoncconnnornoncnnnnnnnnnnnnnnnnnnnos 151 Do you offer any workshops or other training opportunities for NetLogo 151 What s the difference between StarLogo MacStarLogo StarLogoT and NetLogo 152 Has anyone built a model Of lt x gt 2 ie eeeeeaeaaeeerenanaaaaeaaarereaaanananna 152 NetLogo 3 0 User Manual Table of Contents NetLogo Sound Extension Are NetLogo models runs scientifically reproducible nnne 152 Are there any NetLogo textbo00kS ccoocooooocccconocccccononnnonononcccnnnnononnnnncncnnnnnnnoncncnnnnnnns 152 Is NetLogo available in a Spanish version German version your language here Version Oi
35. 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 main window is divided into tabs e Menus e Main Window Interface Tab 0 Interface Toolbar O Working With Interface Elements O View 4 Command Center Procedures Tab Information Tab 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 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 O ee all variables the current state of all turtles and patches he drawing and the output area to a file Export View Save a picture of the current view 2D or 3D to a file in PNG ormat Interface Guide 61 NetLogo 3 0 User Manual 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 he command center to a file im port W
36. In most situations where traditional Logo would use words we simply use strings instead 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 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 The NetLogo world is a torus that is the edges of the screen are connected to each other so turtles and patches wrap around Can use a different world topology bounded infinite plane sphere etc Torus is the only topology directly supported by NetLogo but you can often simulate a different topology without too much extra effort FAQ Frequently Asked Questions 161 NetLogo 3 0 User Manual If you want the world to be a bounded rectangle you may need to add some code to your model to enforce
37. NetLogo incorporates almost all of the extended functionality of our earlier StarLogoT as well as a great many newer features 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 reproducible 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 receive the exact same sequence of random numbers every time 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 152 FAQ Frequently Asked Questions NetLogo 3 0 User Manual 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
38. Questions NetLogo 3 0 User Manual it the way most other programming languages would and the way the same expression would 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 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 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
39. Queue invokeAndWait new Runnable public void run 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 Controlling Guide 135 NetLogo 3 0 User Manual In order to compile and run this Net Logo jar from the NetLogo distribution must be in the classpath 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 me
40. 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 000 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 In each activity you ll see a box on the screen labeled QuickStart Instructions This contains step by step instructions to run the activity Click the Next gt gt gt button to advance to the next instruction 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 116 HubNet Guide NetLogo 3 0 User Manual HubNet Control Center e OS HubNet Control Center i Name everreau Clients Activity Disease Seth Matthew Server address 129 105 107 236 Josh Port number 9173 Craig Esther Andrei Settings Y Mirror 2D view on clients
41. a Clears all lines and stamps drawn by turtles clear output 176 Primitives Dictionary NetLogo 3 0 User Manual clear output ig Clears all text from the model s output area if it has one Otherwise does nothing clear patches cp clear patches pa 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 0 line mode e Name default e Interval 1 0 See also_clear all plots clear turtles ct clear turtles w Kills all turtles See also_die color Primitives Dictionary 177 NetLogo 3 0 User Manual color This is a built in turtle variable It holds the color of the turtle You can set this variable to make the turtle change color See also_pcolor cos cos number Reports the cosine of the given angle Assumes the angle is given in degre
42. 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 Programming Guide 99 NetLogo 3 0 User Manual The user choose directory user choose file and user choose 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 model 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 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 after movie start but before grabbing
43. again Programming Guide 85 NetLogo 3 0 User Manual 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 Buttons and view updates When you edit a button there is a checkbox called Force view update after each run Below the checkbox is a note that reads Checking this box produces smoother animation but may make the button run more slowly Most of the time it s enough to know that if you prefer smooth animation check the box and if you prefer speed uncheck it In some models the difference is dramatic in others it s hardly noticeable It depends on the model What follows is a more detailed explanation of what s really going on with this checkbox To understand why this option is offered you need to understand a little about how NetLogo updates the view When something changes in the world for example if a turtle moves or a patch changes color the change does not always immediately become visible NetLogo would run too slowly if changes always immediately became visible So NetLogo waits until a certain amount of time has passed usually about 1 5 of a second and then redraws the view so that all the changes that have happened so far become visible This is sometimes called skipping frames by analogy with movies Skipping frames is good because each frame takes NetLogo time
44. 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 Primitives Dictionary 253 NetLogo 3 0 User Manual See also min one of without interruption without interruption commands The agent runs all the commands in the block without allowing other agents to interrupt That is other agents are put on hold and do not execute any commands until the commands in the block are finished crt 5 ask turtles without interruption type 1 fd 1 type 2 gt 1212121212 77 because each turtle will output 1 and move 7 then output 2 however ask turtles type 1 fd 1 type 2 gt 1111122222 77 because each turtle will output 1 and move then output 2 word word value value2 word value valuen 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 directory bar txt gt c foo fish bar txt show word 1 54 8 fishy gt 1 54 8 fishy show word a p ec 1 23 gt abcl23 wrap color wrap color number wrap color checks whether number is in the NetLogo color range of O to 140 not including 140
45. and have the wolves try to eat the sheep You define breeds using the breeds keyword at the top of your model before any procedures breeds wolves sheep 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 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 create custom sheep cct sheep for short hatch sheep sprout sheep sheep here and sheep at 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 turile s breed like this if breed wolves Note also that turtles can change breeds A wolf doesn t have to remain a wolf its whole life Let s change a random wolf into a sheep ask random 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 breeds mice frogs mice own cheese to setup ca create custom m
46. 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 separate independent model runs To do this you ll need to write some Java code using our Controlling API See the Controlling section of the User Manual We know of a number of users who are already using NetLogo on clusters you might be able to share techniques with others on the_NetLogo Users Group We don t have any plans to make it possible to split a single model run across multiple computers FAQ Frequently Asked Questions 159 NetLogo 3 0 User Manual Can use screen edge x or screen edge y etc as the minimum or maximum of a slider At present no In a future version of NetLogo we plan to support this Can change the choices in a chooser on the fly At present no In a future version of NetLogo we plan to support this Can divide the code for my model up into several files At present no In a future version of NetLogo we plan to support this Programming How is the NetLogo language different from the StarLogoT language How do convert my StarLogoT model to NetLogo We don t have a document that specifically summarizes the differences between these two programs If you have built models in StarLogoT before then we suggest reading the_Programming Guide section of this manual to learn about NetLogo particularly the sections on Ask and Agentsets Lo
47. 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 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 want 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 Code Example Movie Example 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 100 Programming Guide NetLogo 3 0 User Manual perspective of the obeserver 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 rid
48. asse A E Aa EOKA RENANE ES 139 MO OS e eg Ie ea e e 139 NetLogo 3 0 User Manual Table of Contents NetLogo GoGo Extension WINK OWS EIEE EEN E SA A 140 LIMUSA ad 140 Using the GOGO EA aso Node 140 PUES ii 141 OOO rita AA AA o 141 O NM e O cede etek tee Se ie aetna ede ml el cela Sed E ele das ac eet a dani 141 O a e RN 141 QOQO DOMS is 141 OUIDUL POr COAS divina a ada 142 OUTS UTS DOMSOM urraca ead SAR OR UE RO 142 ouipui pori reverse ee tene ne eran eee ee aaa eee ee ee seaee ae aaaae nese ee saaeeaaaaaneeeeneneaea 142 output port that hiS IWAY oooocoocccnnconncncccncnnccnnncnnnr nn nr rn rre 142 talk 10 0UIpUI PONS sas sita said aa 142 o BRANDA aa aeaa o ON RR SS rages ea DR RR PRP teal 143 SOUS Ol id e de Do Re RCA sive a als eee e achat do pa da e R a REA a oes ce Pe 143 sei ouipui pori powelr n eeee eee e eee ce ee eeeeenae teense eeeeeaaaae ne eeeeeceseaeaaaaaeeeeeseseenenaaes 144 NetLogo Sound EXPENSAS a si 145 USING the Sound EXACTS ION rsss rdias ty cts tap RENA E tanto uagaeane 145 PEVE S a A ap eanls Dorsa dolce Sobdtc oh ols able diye Maids ies 145 AUN Si IS A ae be He Re ath 145 INSIFUMENIS id tn E lean alates a Oe Meas eae eat a dna ta cme 145 ENEE AUI AAE A A EAR RE ES REDE SERES PR A 146 pla Dt spas ao ssa Aa 146 SETE 2s SNS RES AE SRD DES ND RIR NADO SO Av DER RSRS oS 146 SOPA ed ated 146 SOS lili eeaae E E E 146 SIO MU SO a da 147 SOUNGINAMES ss nais A E EE E E E E
49. 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 clad guarantee due to the possibility of random hardware failure and also due to the possibility of human error in the design of your model NetLogo your Java VM your hardware and so on 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 have not yet been able to find the time to make these happen If people 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 interpreted but we a
50. current item in the list Here is another example of map show map lt 0 1 1 3 4 2 10 7 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 21 and 22 are used in place of Here is an example of sort by show sort by 1 lt 2 4 1 3 2 7 prints 1 2 3 4 Varying Numbers 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 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 Math NetLogo supports two different kinds of math integer and floating point Integers have no fractional part and may range from 2147483648 to 2147483647 2 31 to 231 1 Integer operations that exceed this rang
51. energy sheep own grabbed used to prevent two wolves from eating the same sheep patches own countdown to setup ca set ticks 0 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 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 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 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 70 Interface Guide NetLogo 3 0
52. examples of how to make agentsets 7 all red turtles turtles with color red all red turtles on my patch turtles here with color red 82 Programming Guide NetLogo 3 0 User Manual 7 patches on right side of screen 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 7 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 5 turtles standing on my neighboring four patches turtles on neighbors4 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 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 random one of For example we can make a randomly chosen turtle turn green set color of random one of turtles green Or tell a randomly chosen patch to sprout a new turtle ask random 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 ask max one of turtles sum assets die e Make a his
53. 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 Caution The extensions facility is new in NetLogo 2 0 1 and is still in an early stage of development Therefore it is considered experimental It is likely to continue to change and grow If you write an extension now it may need changes in order to continue to work in future NetLogo versions e Using Extensions e Writing Extensions The NetLogo API Specification contains further details Using Extensions NetLogo extensions have names that end in jar short for Java Archive To use an extension in a model add the __ extensions keyword at the beginning of the Procedures tab before declaring any breeds or variables The keyword begins with two underscores to indicate that it is experimental In a future NetLogo version it may have a different name and syntax __ extensions takes one input a list of strings Each string contains the name of a NetLogo extension For example extensions sound jar NetLogo will look for extensions in two places the directory that holds the model and the NetLogo extensions folder So to install a NetLogo extension for use by any model put the extension file for example sound jar in the extensions directory inside the NetLogo directory Or you can ju
54. file If there is no original file a new blank file will be created in its place The user needs to have writable permission in the file s directory 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 myfile in txt print file read line gt First line in file File is in reading mode file open C NetLogo myfile out txt 7 assuming Windows machine file print Hello World File is in 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
55. from the original agentset that fall in the cone The distance to a patch is measured from the center of the patch in cone allows its distance measurements to wrap around the edge of the world in cone nowrap does not ask turtles ask patches in cone 3 60 set pcolor red 5 each turtle makes a red splotch of patches in a 60 degree cone of radius 3 ahead of itself in radius in radius nowrap agentset in radius number agentset in radius nowrap number mt XE Reports an agentset that includes only those agents from the original agentset whose distance from the caller is less than or equal to number The distance to or a from a patch is measured from the center of the patch in radius allows its distance measurements to wrap around the edge of the screen in radius nowrap does not ask turtles ask patches in radius 3 set pcolor red 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 random one of sheep 77 an agent monitor opens for a random turtle from 7 the sheep breed Primitives Dictionary 203 NetLogo 3 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 list is number is patch
56. gt length 2 1 2 strings end show longest string hi there gt there 7 count the number of occurrences of an item in a list to report occurrences x xs report reduce ifelse value 2 x 21 1 1 fput 0 xs end show occurrences 1 1 21312311451 gt 6 7 evaluate the polynomial with given coefficients at x to report eval polynomial coeffs x report reduce x 1 2 coeffs end evaluate 3x 2 2x 1 at x 4 show eval 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 negative numbers remove remove item list remove string 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 7 mylist is now 2 4 Bob show remove na banana Primitives Dictionary 229 NetLogo 3 0 User Manual gt pa remove duplicates remove duplicates list Reports a copy of list with all duplicate items removed The first of each item remains in place set mylist 2 7 4 7
57. 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 primitives beep clear output date and time export view export interface export output export plot export all plots export world import drawing import pcolors import world mouse down mouse inside 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 choice user choose directory user choose file user choose new file user input user message user yes or no write File primitives file at end file close file close all file delete file exists file open file print file read file read characters file read line file show file type file write user choose directory user choose file user choose new file List primitives but first but last empty filter first foreach fput is list item last length list lout map member modes n values position random n of random one of reduce remove remove duplicates remove item replace item reverse sentence shuffle sort sort by sublist values from 168 Primitives Dictionary NetLogo 3 0 User Manual String primitives Operators lt 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
58. 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 Programming Guide 95 NetLogo 3 0 User Manual 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 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 lt 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 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
59. in the HSB spectrum in NetLogo s color space All three values should be in the range 0 0 to 1 0 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 196 Primitives Dictionary NetLogo 3 0 User Manual brightness may vary but not both at least one of the two is always 1 0 show hsb 0 0 0 gt 0 0 black show hsb 0 5 1 0 1 0 gt 85 0 cyan See also extract hsb rgb extract 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 behavior 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
60. 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 0 you can change the interval The plot command is especially handy when you want your model to plot a new point at every time step Example to setup plot count turtles end 94 Programming Guide NetLogo 3 0 User Manual 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 plotxy 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 If you want to move the pen without plotting you can use the plot pen up command ppu for short After this command is issued the plot and plot xy comm
61. is on for the current plot false otherwise auto plot off auto plot on auto plot off auto plot on This pair of commands 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 display 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 See also forward jump Primitives Dictionary 173 NetLogo 3 0 User Manual beep beep Emits a beep Note that the beep is emitted immediately so several beep commands in succession will only produce a single audible sound Example beep 7 emits one beep repeat 3 beep 7 emits 3 beeps at the exact same time 77 so you only hear one sound repeat 3 beep wait 0 1 produces 3 beeps in succession seperated by 1 10th of a second breed breed This is a built in turtle variable It holds the agentset of all turtles of the same breed as this turtle For turtles that do not have any particular breed this is the turtles agentset of all turtles You can set this variable to change a turtle s breed See also_bree
62. is setup turtles to setup turtles crt 100 ask turtles fd random screen edge x end Setup turtles is exactly what we were doing in the old setup procedure After typing all of this in press the setup button back in the Interface tab Voila A lush NetLogo landscape complete with turtles and green patches appears After seeing the new setup work a few times you may find it helpful to read through the procedure definitions again Here s a way for you to see what diffuse does Return to the Procedures tab and use a semicolon to deactivate the diffuse command like this 50 Tutorial 43 Procedures NetLogo 3 0 User Manual diffuse elevation 1 Semicolons are very useful in writing procedures They can be used as above to save you from having to delete code to try something else out and then having to rewrite them Also they can be used to add some explanatory text to your procedures A lot of people like to do this to make their procedures more readable to others Notice that all the text to the right of a semicolon becomes gray Press setup again looks different doesn t it This is because as mentioned above diffuse has each patch share its value of elevation with all its neighbors by having every patch reset its value of elevation to a new value that depends on the value of e evation all around it For further explanation of how diffuse works go to the_Primitives Dictionary if you d like Also it may help
63. itself If it is not wrap color wraps the numeric input to the 0 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 150 254 Primitives Dictionary NetLogo 3 0 User Manual 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 See also output write X xcor xcor k This is a built in turtle variable It holds the current x coordinate of the turtle This is a floating point number not an integer You can set this variable to change the turtle s location This variable is always greater than or equal to screen edge x and strictly less than screen edge x See also_setxy ycor pxcor pycor 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 an
64. 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 less 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 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 Tl 83 graphing calculators and the Tl Navigator Classroom Learning System Note that Calculator HubNet works with a prototype version of the Tl Navigator system and is not yet compatible with the commercially available TI Navigator We are actively working in partnership with Texas Instruments on integrating the new TI Navigator with Calculator HubNet which we expect to release in the near future For more information on HubNet see the HubNet Guid
65. maps that are images not maps in other formats We do not have built in support for reading common GIS formats However a number of our users are working with GIS data succesfully using NetLogo code that reads GIS data using our file 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 or the no display command to freeze the view temporarily For example to go no display display end FAQ Frequently Asked Questions 157 NetLogo 3 0 User Manual If you use this technique you should turn off the Force view update checkbox since the display command already forces a view update e If your model is using all available RAM on your computer then installing more RAM should help If your hard drive
66. menu e scrollable Interface tab e contextual menus in Interface tab e new primitives Version 1 0 April 2002 e initial release after a series of betas What s New 11 12 NetLogo 3 0 User Manual What s New System Requirements NetLogo is designed to run on almost any type of computer but some older or less powerful systems are not supported The exact requirements are summarized below If you have any trouble with NetLogo not working on your system we would like to offer assistance Please write bugs ccl northwestern edu System Requirements Application On all systems approximately 25MB of free hard drive space is required Windows e Windows NT 98 ME 2000 or XP e 64 MB RAM or probably more for NT 2000 XP You can choose to include a suitable Java Virtual Machine when downloading NetLogo If you want to use a JVM that you install separately yourself it must be version 1 4 1 or later 1 4 2 or later is preferred Windows 95 is no longer supported by the current version of NetLogo Windows 95 users should use NetLogo 1 3 1 instead We will continue to support NetLogo 1 3 1 Mac OS X e OS X version 10 2 6 or later 10 3 or later is recommended e 128 MB RAM 256 MB RAM strongly recommended On OS X the Java Virtual Machine is supplied by Apple as part of the operating system OS X 10 3 includes an appropriate JVM OS X 10 2 users must install Java 1 4 1 Update 1 which is available from Apple through
67. observer Refer to the Interface Guide for details explaining the different parts of the Command Center Tutorial 2 Commands 35 NetLogo 3 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 A Clear observer gt ask patches i 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 y observer gt ask patches set pcolor yellow observer gt v e Type in the white box at the bottom of the Command Center the text shown below 36 Tutorial 2 Commands NetLogo 3 0 User Manual Command Center Clear observer gt ask patches set pcolor yellow observer gt ask turtles a set color brown J ba Was the result what you expect
68. 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 134 Extensions Guide 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 Example with GUI e Example headless e BehaviorSpace e Other Options e Conclusion The NetLogo API Specification contains further details 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 org nlogo compiler CompilerException import java awt EventQueue public class Examplel public static void main String argv App main argv try Event
69. other so turtles and patches wrap around Can use a different world topology bounded infinite plane Sphere CtC 2 160 vi NetLogo 3 0 User Manual Table of Contents NetLogo Sound Extension How do take the negative Of a NUMDEN cccccccccccesssseeeeeeeeeeeeeeseeseseeeeeeeeesssesnaaees 161 My turtle moved forward 1 but it s still on the same patch Why occccnonocococcncnccccnnnnnns 162 patch ahead 1 is reporting the same patch my turtle is already standing on Why 162 How do give my turtles VISION PR ccciccscnssacetectssdabecttacictisdeteddnaved t qua sda gue do dieta ad sacada 162 Does NetLogo have a command like StarLogo s grab command 163 tried to put at after the name of a variable for example variable at 1 0 but NetLogo won t let me Why not e eeererarereeaaeaaaaeaaareresaaana 163 I m getting numbers like 0 10000000004 and 0 799999999999 instead of 0 1 and OBVIO O ES sats oases E Sp 163 How can keep two turtles from occupying the same patch 163 How can find out if a turtle is dead eretas eerrer tara 163 How do find out how much time has passed in my model nnn 164 Does NeiLogo have arrays 2 caia mera na A AS 164 Does NetLogo have associative arrays or lookup tables nnn 164 How can use different patch neighborhoods circular Von Neumann Moore CICS ati aiii di ie 164 Can connect tu
70. patch at patch at heading and distance Primitives Dictionary 219 NetLogo 3 0 User Manual patches patches Reports the agentset consisting of all patches patches from patches from agentset reporter Reports a patch agentset made by gathering together all the patches reported by reporter for each agent in agentset For each agent the reporter must report a patch agentset a single patch or nobody patches from turtles patch here 7 reports the set of all patches with turtles on them if there are many more patches than turtles this will 7 run much faster than patches with any turtles here See also_turtles from patches own patches own var7 var2 This keyword like the globals breeds 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 breeds lt BREED gt own pcolor pcolor Ent 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 the patch See also_color 220 Primitives Dictionary NetLogo 3 0 User Manual pen down p
71. prints the number of turtles turtles at BREED at turtles at dx dy BREED 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 breeds cats dogs create custom dogs 5 show count dogs at 2 gt 5 setxy 2 3 3 turtles from turtles from agentset reporter Reports a turtle agentset made by gathering together all the turtles reported by reporter for each agent in agentset For each agent the reporter must report a turtle agentset a single turtle or nobody turtles from patches random one of turtles here 7 reports a turtle set containing one turtle from 7 each patch that has any turtles on it turtles from neighbors turtles here 5 if run by a turtle or patch reports the set of 5 all turtles on the neighboring eight patches note that 7 this could be written more concisely using turtles on 7 like this va turtles on neighbors See also patches from turtles on 246 Primitives Dictionary NetLogo 3 0 User Manual turtles here BREED here turtles here BREED here Reports an agentset containing all the turtles on the caller s patch including th
72. setup and go are user defined commands e ca Clear all crt create turtles ask 1t left turn and rt right turn are all primitive commands 76 Programming Guide NetLogo 3 0 User Manual 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 O 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 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 ca 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 dra
73. tar How do install NetLogo on Windows 2003 or Windows Server 2003 On these operating systems the NetLogo installer might not work unless you change some settings in the installer as follows 1 Locate the installer and right click on it 154 FAQ Frequently Asked Questions NetLogo 3 0 User Manual 2 Select Properties 3 Select Compatibility tab 4 Check Run this program in compatibility mode for 5 Select Windows XP 6 Click OK 7 Run the installer 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 Here s how to get the right Java e If you re on Windows 98 or newer 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 already has the right Java You must also use a web browser that supports Java 1 4 Internet Explorer does not work Safari does 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 downl
74. than one interface element with the same Display Name in the client interface will cause unpredictable behavior For instance if we had a monitor called Milk Supply and a plot named Milk Supply when we send data to the client using the tag Milk Supply the client will just pick either the plot or the monitor to give the data to If you wish to have a View in the client for a model the view in the client and the one in the NetLogo model must have the same number of patches and the same patch size If they do not the view on the client will not display information sent by the server If you wish to make a client without a view in the client you will have to hand edit the file after you have finished adding all the other interface elements in NetLogo To do this open the client file ina text editor such as Notepad on Windows or TextEdit on Macs You should see a file that starts with something similar to this add model procedures her CHSHCHS HE GRAPHICS WINDOW 321 10 636 325 17 E7 9 0 ih 10 0 0 HubNet Authoring Guide 125 NetLogo 3 0 User Manual CC WINDOW 323 339 638 459 Command Center You should remove all the text that is in the GRAPHICS WINDOW section and then save the file So that after you are done the beginning of the file should look similar to this add model procedures her C SHCHS EG CC WINDOW 323 339 638 459 Command Center For more examples study the models and i
75. 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 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 Primitives Dictionary 201 NetLogo 3 0 User Manual import pcolors import pcolors 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 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 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 format supports transparency alpha then all fully transparent pixels will be ignored Partially transparent pixel
76. the list the list is sorted in numerically ascending order and any non numeric items of the input list are discarded If there are no numbers but at least one string in the list the list is sorted in alphabetically ascending order and any non string items are discarded sort by 240 Primitives Dictionary NetLogo 3 0 User Manual sort by reporter 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 1 and 2 to refer to the two objects being compared reporter should be true if 1 comes strictly before 2 in the desired sort order and false otherwise 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 1 lt length 2 zzz z zz gt 2 Weg egg sprout sprout lt BREED gt sprout number commands sprout lt BREED gt number commands E Creates number new turtles on the current patch The new turtles have random colors and orientations and they immediately run commands This is useful for giving the new turtles different colors headings or whatever If the sprout lt BREED gt form is used the new turtles are created as members of the given breed sprout 1 set color red sprout sheep 1 set color black Note While the commands are running no other agents are allowed to run any code as with the without interr
77. these commands compares its own value of elevation to our global variables highest and lowest If the comparison reports true the patch executes the commands inside the brackets In this case the patch changes its color If the comparison reports false the patch skips over the commands inside the brackets These ifs cause all patches whose value of elevation is NEAR to the highest within about 1 for our values change their color to white and all patches whose values are NEAR to the lowest become black We want this so that they ll be easier to see You can make a couple of quick changes here if you wish they won t affect the rest of the model For example instead of saying set pcolor white and set pcolor black you can say set pcolor blue and set pcolor red or whatever other colors you may wish Also you can change the range of highest peaks and lowest peaks by changing the number 100 to some other number After this 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 Name one of them highest and the other one lowest The reporters you ll want in each of them happen to be highest and lowest as well If you want to learn more about reporters you can look them up in the NetLogo Programming Guide Now every time you click setup and redistribute the values of elevation you ll know exactly what the highest and lowe
78. this Often a helpful technique is to turn the edge patches a different color so turtles can easily detect when they hit the edge Also there are no wrap versions of primitives such as distance and towards these should help If you want your turtles to move over an infinite plane you can simulate this by having the turtles keep track of their position on the infinite plane then hide the turtle when it goes out of bounds The Random Walk 360 model in the Models Library shows you how to code this Simulating a spherical or other topology might be difficult we haven t seen a model that does this If you have one please send it in How do take the negative of a number Any of these ways x o ex 0 38 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
79. 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 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 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 Version the version of NetLogo for which this JAR is intended If a version mismatch is detected when a JAR is imported a warning message will be issued and the user will have the opportunity to cancel If the user chooses to continue NetLogo will attempt to import the JAR anyway which of course may fail Here s a manifest for our exa
80. to toy with the values being passed to it and see what happens We re now prepared to create some kind of dialog between the turtles and the patches In fact we even have an idea for a project here Notice that we called the patch variable elevation and that our landscape sort of looks topographical We re going to have our turtles do what is called hill climbing where every turtle seeks to find the highest elevation it can In order to do this we will learn how to write more complex instructions Go to the Command Center and type O gt show max values from patches elevation and show min values from patches elevation These two reporters will respectively search over all the patches to return to you the highest elevation and the lowest These commands work like this you can read about them in the NetLogo Primitives Dictionary Look up values from in the dictionary It shows values from AGENTSET expression and says it returns a list In this case it looks at the expression elevation for each agent in the agentset patches and returns all of these as a list of elevations Look up min in the dictionary It shows min list and says it s a reporter So it takes the list of elevations and reports the smallest value Show displays this value in the command center We will use these reporters max values from patches elevation and min values from patches elevation in our model Just in case we
81. 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 86 Programming Guide NetLogo 3 0 User Manual 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 Synchronization In both StarLogoT and NetLogo commands are executed asynchronously each turtle or patch does its list of commands as fast as it can In StarLogoT one could make the turtles line up by putting in a comma At that point the turtles would wait until all were finished before any went on The equivalent in NetLogo is to come to the end of an ask block If you write it this way the two steps are not synced ask turtles fd random 10 do calculation Since the turtles will take varying amounts of time to move they ll begin do calculation at different times But if you write it this way they are as
82. 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 Edit button in the control strip i gt The 3D View has a similar control strip but it looks slightly different and as you may notice a few of the controls are missing However the controls that are present work exactly the same as the 2D View Control Strip Speed 0 Edit The controls in the control strip work as follows e The three sets of black arrows let you change the size of the world 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 e The button with the arrowhead 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 Interface Guide 65 NetLogo 3 0 User Manual e The on off switch lets you temporarily freeze the display The model keeps running but the contents of the view don t change until you unfreeze it by flipping the switch again Most models run much faster when the view is frozen e The 3D button switches to the 3D View see below Here are the settings for the View accessible by editing the View or by pressing the Edit
83. 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 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 19 20 NetLogo 3 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 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 s
84. with the without interruption command This ensures that the new turtles cannot interact with any other agents until they are fully initialized In addition no screen updates take place until the commands are done This ensures that the new turtles are never drawn on screen until they are fully initialized create tempora ry 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 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 0 line mode e Interval 1 0 See clear plot clear all plots and set current plot pen D Primitives Dictionary 179 NetLogo 3 0 User Manual 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 h
85. 0 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 58 Trombone 59 Tuba 60 Muted Trumpet 61 French Horn 62 Brass Section 63 Synth Brass 1 64 Synth Brass 2 148 NetLogo 3 0 User Manual 81 Square Wave 82 Sawtooth Wave 83 Calliope 84 Chiff 85 Charang 86 Voice 87 Fifths 88 Bass and Lead Synth Pad 89 New Age 90 Warm 91 Polysynth 92 Choir 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
86. 0 and 359 degrees as a multiple of 90 degrees in the direction of the maximum value of the variable patch variable of the four patches to the north south east and west of the turtle If there are multiple patches that have the same greatest value a random patch from those patches will be selected See also_uphill downhill downhill4 user choice user choice value list of choices Opens a dialog with value displayed as the message and a button corresponding to each item in list of choices Reports the item in list of choices that is associated with the button the user presses value may be of any type but is typically a string if yes user choic Set up the model Eno yes setup user choose directory user choose 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 choose directory 7 Assumes the user will choose a directory Primitives Dictionary 249 NetLogo 3 0 User Manual user choose file user choose 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 choose fil j Assumes the user will choose a file user choose new file user choose new file Opens a dialog that allows the user to choose a new file on the system It r
87. 1 Low Floor Tom 42 Closed Hi Hat 43 Hi Floor Tom 44 Pedal Hi Hat 45 Low Tom 47 Open Hi Hat 47 Low Mid Tom 48 Hi Mid Tom 49 Crash Cymbal 1 50 Hi Tom 51 Ride Cymbal 1 52 Chinese Cymbal 53 Ride Bell 54 Tambourine 55 Splash Cymbal 56 Cowbell 57 Crash Cymbal 2 58 Vibraslap Instruments Piano 1 Acoustic Grand Piano 2 Bright Acoustic Piano 3 Electric Grand Piano 4 Honky tonk Piano 5 Electric Piano 1 6 Electric Piano 2 7 Harpsichord 8 Clavi Chromatic Percussion 9 Celesta 10 Glockenspiel 11 Music Box 12 Vibraphone 13 Marimba 14 Xylophone 15 Tubular Bells 16 Dulcimer Organ NetLogo Sound Extension NetLogo 3 0 User Manual 59 Ride Cymbal 2 60 Hi Bongo 61 Low Bongo 62 Mute Hi Conga 63 Open Hi Conga 64 Low Conga 65 Hi Timbale 66 Low Timbale 67 Hi Agogo 68 Low Agogo 69 Cabasa 70 Maracas 71 Short Whistle 72 Long Whistle 73 Short Guiro 74 Long Guiro 75 Claves 76 Hi Wood Block 77 Low Wood Block 78 Mute Cuica 79 Open Cuica 80 Mute Triangle 81 Open Triangle Reed 65 Soprano Sax 66 Alto Sax 67 Tenor Sax 68 Baritone Sax 69 Oboe 70 English Horn 71 Bassoon 72 Clarinet Pipe 13 PLeEOLO 74 Flute 75 Recorder 76 Pan Flute 77 Blown Bottle 78 Shakuhachi 79 Whistle 80 Ocarina Synth Lead 147 17 Drawbar Organ 18 Percussive Organ 19 Rock Organ 2
88. 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 order 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 cou
89. 5 0 lime 65 0 turquoise 75 0 cyan 85 0 sky 95 0 blue 105 0 violet 115 0 magenta 125 0 pink 135 0 See the_Colors section of the Programming Guide for more details A abs abs number Reports the absolute value of number show abs 7 gt 7 show abs 5 gt 5 170 Primitives Dictionary NetLogo 3 0 User Manual acos acos number Reports the arc cosine inverse cosine of the given number The input must be in the range 1 0 to 1 0 The result is in degrees and lies in the range 0 0 to 180 0 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 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 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_nobody Arithmetic Operators 4 lt gt ls lt gt All of these operators take two inputs and all act as infix operators going between the two inputs a
90. 5 40 4 43 48 49 49 9 green 55 50 52 53 58 59 59 9 lime 65 60 62 63 68 69 699 turquoise 75 70 722 73 78 79 79 9 cyan 85 80 82 83 8 88 89 89 9 sky 95 90 91 92 E 98 99 99 9 blue 105 100 101 102 103 108 109 109 9 violet 115 110 111 112 113 117 118 119 1199 magenta 125 120 121 122 123 128 129 129 9 pink 135 130 131 132 133 5136 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 if you 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 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 e Type 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 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 40 Tutorial 2 Commands NetLogo 3 0 User Manual e Press setup to get the red car to reappear e If you are o
91. 50 randomly chosen patches turn green See also random one of random one of random one of agentset random 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 random one of patches set pcolor green 7 a random patch turns green set pcolor of random one of patches green another way to say the same thing ask patches with any turtles here show random one of turtles here for each patch containing turtles prints one of 7 those turtles 7 suppose mylist is 1 2 3 4 5 6 show random one of mylist 7 prints a value randomly chosen from the list See also one of and random n of 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 2147483648 to 2147483647 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 random seed 47823 Primitives Dictionary 227 NetLogo 3 0 User Manual show random 100 gt 57 show random 100 gt 91 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 special v
92. A Ui A 87 NetLogo 3 0 User Manual Table of Contents Programming Guide la A DU A a 87 Ma ade 90 NO rare eraae rara era ear een ar eae r aaa aa anna ear ee nara EEEE anna 92 Turtle shape Se turista rica de lgan a anos Dead rca calca Relata adelante odiada 93 PIONING e ciiesntinsi e TAL ae E TOT Ba Dama a LD TO Dad aaa 94 SILAA O EMEA SR Wh RR A RR PR OS 97 OUEN te e A O RS eects 98 El tL O REAR RR AR RR SAD is e eden os 98 MOVIES 3 2 SEN RIDER A PEIN RO SR 100 Persp tivel arica ia inss da ol besa TAS DO denis adv made ga ieee ges erga SIS a 100 US BENS a o Ota Mat A A ga dn Rt RDA de A Ro A ee 101 Shapes Editor Guide ari 103 Getting Stated tt a e di 103 PTS OAL SAPOS ad O duoc dia ANN RUDE AN DEN ER ED A 103 Creating and Editing SAPOS da 104 TO ii A AA A ee AR RT 105 PLOVI WS da 105 Overlapping A assa a dA SEE A RENNES E RN 105 LH Fa Lo o tt A RO RR RR nae Sls T ae RE AR RR O RR E 105 OID RS qu Gatto Bet cae cSt Sent ene thd dun antec E tai ea Dodi DS 105 OTS DUTIONS sc EE este E diet a Mata ei teaet a 106 Shape DOSIS Ni 106 Kesping A o 106 Using Shapes in a Model 106 Behavior Space Guide ea eaa ra namaa naiara aA aa ils oa baseadas ada 107 Whatis BehaviorSpate Z senape taste id ds 107 Why BenavorSpacez vita a N ua a a a 107 Historical Nol sos eset A E A O AA 108 DEAA LALE E AET cita 108 Managing experiment SCtUDS oooocccococonocononononnonononononnnonononnnonononnnnnnnnnnnnnnnnnnnnnnnnonnnnnnnnnnos 108 Creating
93. A ida A a Je ai reed 222 A ERAN A E 222 plot NaME unida ias 222 plot pen down ppd plot pen up PU ccccccnccnccnncnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnrrnnr rana rnnrnnns 222 plOT PEN TOS Odia A id 222 PODA NN tdi RN 223 plot x min plot x max plot y MiN plot y max eee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeees 223 POSTUON S e Sues escape A AAA A dels 223 DIECISION onea e ae aE A AR EA AAA A RA el eee a 223 RIA 224 PXCOF DY CO iii 224 E A A AIN A A A A AS 224 ANO M Bets cs Dates ste Tae Qi ind teak dekh Ga O Pina E O DE ia o a ci Be ar da Ds dedos a 224 random iloal casas ana oe cee ee ea ie SC a SEDE ect daa Aa ke eres ot ah eens DT 225 random exponential random gamma random normal random poisson 225 FANGOM iNt OF lun edad 226 Re lale Lol AAE A EO tard tt tl id au shin 226 cl A A 227 FANGOM SSCO ta A nba AA Daba 227 1890 TROM Stns chapa datada 228 CAU e Ra Da e cet O Scns E a 228 KEARE MLS 1 AEA RN 229 KANALON AE E E E E E T in 229 rEMOVE dUPICA OS iia aa aca tia 230 AN TN 230 A O cursus Mane dE aude ce paraiso daiane 230 FEPIACE ANS Mocanal daaalc a 230 O uv A A A O RREO A 231 reset perspective rp ce eeeeeeeaaeeaaeaaae rena nana nara nana nana nana nana nana nanananaa 231 A A as Ce rude o atk Rit URU Oi a O a ota Sa lac ate co tected ET 231 RENASTE sacas ea uia aN E SR D O Td agito a o DN ES Ghat Saal 231 TIED src Er SO a Sa 231 Ml da ata 232 RICE mesa euro e AO AA NO E A A e
94. ALINGS IN THE SOFTWARE 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 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 control of aircraft air traffic aircraft navigation or aircraft communications or in the
95. Da aes 122 Sendi gd A A SR E 123 Example Senerare ada 124 Calculator HubNet INfOrMAtiQN ccccoonccncnnnnccncnnonccnnnnonccnnnnnoconononanonono nono nano nana cann cnn cancnnancanns 124 DANO A RAN 124 Computer HubNet Into Mata aa dao 125 How To Make an Interface for a Client rrenan 125 View Updates on tne Cl ia da 126 Plot Updates on the CliOnts cccccccsceccceecsssennneeeeeeeeeseeeeeeeeeeeeeseessesneeseeeeereeessennaaees 127 Clicking in the View on Clients ii ias 127 Text Area for Input and DiS Slay es isccos savivuaasecseinernstaseasnisarbesaxstawelatbelolanntashepeatdepataatdad 127 Extensions Guide nui A A E Bett ee 129 Using EXTENSIONS arrea aaa iia 129 Applets iia A A pei EDTA Da eA 130 Writing EXTENSIONS z heie eee dia e aan ea e aa a E e AEE e Seod aaia 130 SUMA a a na id E T 130 Toora a eta aa 130 Extension development tipS coocccccccncccnncnnncnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnonnnonanonenenineness 133 CONCIUSION sa treed te ir face ia ia aid 133 Controlling GU jde ss sra cu eee Di iia 135 Example QUI GUI estao asda GUI CE DADE Rd SG CO OSS af Gala Sa 135 Example headleSs j r ra des nine a UT a aa 136 BENAMIOLS DAC E ada rd aa io ao de AG A trade ara dd 137 Other Options assar ts minar ada iS id 138 GONCIUSION mc AE a eee Qua A gago is 138 Neil 690 GoGo Extension a cd 139 What tS the Gogo Board rannan aR ESEO A AREE a 139 How to geta Gogo B ard aci A aa 139 Installing the GOGO EXTSNSION
96. ECREIO RR izo 215 A Pee E A RR 215 ile o o jo Mere RE error RUE ON Tre Oro TOT CTT Tere Tear ec Te eee 215 o ESPERO cece weeds A A id 215 HUSUNI SAS I a AR e a a e aa ad dedo Bee oA eal hh NT a 216 O JRR RR RR a Sete sh oa ae e ah ale ty a RODE JR RT a NO 216 OL a talo Al AD nn RPE a ee A 216 OMG SOL Bae en ees han etek ces Sire es elena Ue Ne achat as Hae ado al ie Sc none Gate A 216 Dr de 217 other turtles here other BREED N8lB cocoocccccncccnnoconcnccnoncncnnnnononanonnnnanonnnno nana nnnnananannns 217 output print output show output type output write ooocooccooonoconoonnnononononnnnnnnnnononononnnnos 217 Ps A opcao A fa qu ad gia E AEAEE mA cad ae aa cP 218 O a Ne EA AA dna n E ate sabes ES A E ci 218 o A NN 218 p tch at ee AAA AA aia 218 patch at heading and distance errar aeee rre 219 DatC MEMOS essa id AA CEA Aida do R tates SA Rad RU da 219 patch left and ahead patch right and ahlead cccccccononoconcncncconnnanannncnnnnoncnnnnnnnnnnnos 219 Patches ito AA ada 220 DAICHOS TOM adoos 220 PalChESSOWN A A dada 220 o 670 o PEPEE aa 220 pen down pd pen erase pe pen up Pl cccccccnnccnncnnncnnnnnnnnnenenenennnnnnnnnnnnrnnrrnnr rare nn 221 Pen MOdE ici dade RELA aa a Ca dia CT EU SR a 221 PONESIZO A sra sta cipa cul EA E E ad iii 221 xi NetLogo 3 0 User Manual Table of Contents Primitives Dictionary plab l Sama A A E DOS ATORES dO RUE DR Da ea 221 plabel COlO E see e creia
97. MAGES 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 licensed or intended for use in the design construction operation or maintenance of any nuclear facility Sun gratefully acknowledges that this software was originally authored and developed by Kenneth Bradley Russell and Christopher John Kline 6 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 3 0 September 14 2005 e content new network models Giant Component Preferential Attachment Small Worlds new EvoLab evolution models Bug Hunt Camouflage Bug Hunt Speeds new NIELS electromagnetism models Electrostatics Conductor new MaterialSim materials science model MaterialSim Grain Growth new ProbLab probability model 9 Block Stalagmite Central Limit Theorem Dice Stalagmite Expected Value Advanced Pr
98. Mac OS X 10 3 8 10 4 0 and 10 4 1 note Java 1 4 2 is required e Windows 2000 e Windows XP If you use the 3D view on an operating system that we haven t tested we d like to hear about it Please let us know at feedback Occl northwestern edu Please include the information in the System section of About NetLogo Graphics Cards We ve tested the 3D view on many different graphics cards and controllers including e ATI Radeon 7500 e ATI Radeon 9200 e ATI Radeon 9600 e ATI Radeon 9800 XT e ATI Radeon IGP 345 e ATI Radeon Mobility e ATI FireGL V3100 e Intel 82830M e nVidia GeForce MX e nVidia GeForce FX 5200 e nVidia GeForce FX Go5650 e nVidia Quadro NVS 14 System Requirements NetLogo 3 0 User Manual If you use the 3D view with a graphics card that we haven t tested we d like to hear about it Please let us know at feedback ccl northwestern edu Please include the information in the System section of About NetLogo Fullscreen mode Fullscreen mode does not work with some graphics cards and controllers including the ATI Radeon IGP 345 and the Intel 82845 Some users with older computers especially laptops have reported that entering fullscreen mode caused NetLogo to crash If you experience this problem please let us know Library Conflicts NetLogo includes JOGL version 1 1 0 for the 3D View On Mac OS X and Windows NetLogo uses the version of JOGL that comes with NetLogo even if you have a different versio
99. Net Client application on computers connected by a regular computer network In_Calculator HubNet created in conjunction with Texas Instruments participants use Tl 83 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 115 NetLogo 3 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 networked 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
100. R SS aes 240 SIZ Ss ere decor sina ira Ledo Uai sate dna a dk UE SS DE ta ada o E RSS LUAS Sa Cr ba a NA 240 SON grato der a o cin A RNC BP mes nS CORO Rt ORE A IST RD EAS a o a di do 240 SOM D tim 240 Sprout sprout lt BREED gt nein ah pein te 241 O ON 241 stamps fo ep ce heh cca acac peepee RED at npn hence wes RAE VAR OCR RARE RIR e 241 Standard de MAIN 242 E A A 242 ON 242 SUD A Nada 242 SUBIISESUDS Oir e 242 Subtract NeadindS ii ar 243 UN ao e Hie ea oa iaa 243 OD Ane A E cance eae ance o veined eth eset cates Sho ab edit ol da ae Se tc ete edhe a ca 244 a a ER AR dE 244 TA Rese eee act RSRS PARREIRA E EI E RS DRESS PNR ROSANA RM 244 TOP eects ucee Sere adan 244 TOP NED OM ete A a A A A AR BO A ae ee e 244 towards tOWardS NQWIAD occcocccccccncconccononinnnnnnnnn rre 245 towardsxy tOWardSXY DNQWIAD ccccccccccnnccnnnnnnnnnnnnnnnnnnnnnnnnnnnrrnn rn nr rre 245 A A O RUC 245 UA a a ea dl ee ota e soe De dao ato e O E 246 turiles at BREED ales cic cee a Leite los aa il T shell Meteo A ees ete 246 CUPS STON sra secs nas A A E a aa ata ate 246 turtles here BREED NeRe cesar resista eese wees lid 247 turtles on BREED 0D oooccococcccnccnononononcnnnncnonnnccnnnnnnnnn nono nc cnn rca nan cnn nr nena 247 turiles own BREED 0WNO cooocccconcccnancononccnnncnononcconncno anno E AEAT AT 248 Ype a A Aita e RO RR DN 248 Ha A Da Ao E a e o a ee pao ateos Dec RdA 248 O 248 NetLogo 3 0 User Manual Table of Contents Primitives Dic
101. RE TA ca me a O 187 EAN EE A E EEEE rd ida 187 EEAO e EE T E ESE A AEE o O O A 188 Eo EE iia EAA A EE A E AA 188 IA a a a aa a a A N a N 188 TINO Sas esate a E A EA 188 MESA A dia 189 lA A E e 189 tile 6ad ChAracters oi a a ao 190 file tead he dt li tedio 190 TIS SMOW ii a A Ds e a ad te DO a a a A Nd oe 190 MO ida 191 EE A E A A ARO 191 A A RT a 191 A ed ca E oct bossa ab Sos doida Ohta tue tae Sita kin oleate aes Ma io UR o Ud EET E 192 Ma E aU E 192 A NDA NESTE O RSRS ES OS RDI SR NS nek 192 TONOW IMG OEE even dto 192 TOPS AC A A A ad qo GA DO do A A oR NOTR 193 TOrWara TO tas aus A A E ENE LE Sa bia NES SUNGA SA SS NE ada Desa SR NDA Sie 193 A O 193 A A a TR Mie ted tater a e e 8 a 2 ad 194 QIODAIS A A A A A 194 NARA 194 hatch hateh lt BREE Ds 28 tico o 194 h adiNg AN 195 Md E ts Semi Be ae oO A cae ae o NE Da DRE a PO ES TATA 195 A 0 Bere eee meee ne RR RR non RR ee eee 195 histogr m froM n da 195 histograma Ticas a a 196 A a ee o de a do 196 NetLogo 3 0 User Manual Table of Contents Primitives Dictionary LS ee ee ve A e ENE O Pe 196 NUDO Ol adCast ses hack scree di age 197 hubNet brOQAUCaAsSt ViBW ooccccnccccnoccconccnnnccononccnonancnnnnononoccnnnnn nan nn nonaro nan nano nnnnnnann anna nanannns 197 hubnei enter Message aaa ad as 197 hubnat exitamMess ado tia dass ara 197 NUBNEt 1EiCh MOSSAGS ea Mannie AAEE A 198 TNA E E E 198 NUbNEt MESSAGE SOUICE cccccscccseceeeceaecceceeeceeecec
102. 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 timer reset timer Resets the global clock to zero See also timer 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 5 mylist now is Bob 4 7 2 show reverse string gt gnirts rgb 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 Primitives Dictionary 231 NetLogo 3 0 User Manual All three inputs should be in the range 0 0 to 1 0 The color reported may be only an approximation since the NetLogo color space does not include all possible colors See_hsb for a description of what parts of the HSB color space NetLogo colors cover this is difficult to characterize in RGB terms show rgb 0 0 0 gt 0 0 black show rgb 0 1 0 1 0 gt 85 0 cyan See also extract rgb hsb and extract hsb ride ride turtle gt Set the perspective to turtle Every time turtle moves the ob
103. Software Update For OS X 10 3 users installing Java 1 4 2 Update 1 is recommended for improved application reliability The update is available from Apple through Software Update Mac OS 8 and 9 These operating systems are no longer supported by the current version of NetLogo MacOS 8 and 9 users should download NetLogo 1 3 1 instead We will continue to support NetLogo 1 3 1 Other platforms NetLogo should work on any platform on which a Java Virtual Machine version 1 4 1 or later is available and installed Version 1 4 2 or later is preferred If you have trouble please contact us see above System Requirements 13 NetLogo 3 0 User Manual System Requirements Saved Applets NetLogo models saved as Java applets should work on any web browser and platform on which a Java Virtual Machine version 1 4 1 or later is available If you have trouble please contact us see above On Mac OS X the Internet Explorer browser does not make use of the 1 4 1 JVM so it cannot run saved applets We suggest using Apple s Safari browser instead or another web browser which uses the newer JVM Note that the 3D view is not available in applets System Requirements 3D View NetLogo s 3D view is a new feature and hasn t been tested on every configuration Below is information about configurations that we have tested so far Operating Systems We ve tested the 3D view on e Linux 2 6 8 Debian i386 e Linux 2 6 8 Debian amd64 e
104. 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 1ist 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 lists you can use the list reporter with more than two inputs but in order to do so you must enclose the entire call in parentheses like this list 12 3 4 5 For more information see_Varying Numbers 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_values from 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 max values from turtles
105. Turtles at Peaks plot count turtles with elevation gt highest 100 end Note that we use the plot primitive to add the next point to a plot but before doing that we need to tell NetLogo which plot we want since later our model might have more than one plot Thus we re plotting the number of turtles within 100 units of our maximum elevation at some given point in time The plot command moves the current plot pen to the point that has x coordinate equal to 1 greater than the old x coordinate and y coordinate equal to the value given in the plot command in this case the number of turtles whose elevation is within 100 of highest Then the plot command draws a line from the current position of the plot pen to the last point it was on In order for set current plot Turtles at Peaks to work you ll have to add a plot to your model in the Interface tab then edit it so its name is Turtles at Peaks the exact same name used Tutorial 3 Procedures 55 NetLogo 3 0 User Manual in the code Even one extra space will throw it off it must be exactly the same in both places Note that when you create the plot you can set the minimum and maximum values on the x and y axes and the color of the default plot pen pick any color you like 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 dat
106. User Manual 00 Find Find sheep Replace with wolves Y Ignore case Y Wrap around Replace All Replace Replace amp Find Previous 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 8 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 procedures tab to change the indentation level of your code or add and remove semicolons which mark comments from sections of code For more information about writing proc
107. Y org nlogo headless HeadlessWorkspace 112 BehaviorSpace Guide NetLogo 3 0 User Manual 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 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 tag Example lt experiments gt lt experiment name experiment repetitions 10 runMetricsEveryTick true gt lt setup gt setup lt setup gt lt go gt go lt go gt
108. a Now reset the project and run it again You can now watch the plot be created as the model is running If you notice that your plot doesn t look exactly like the picture below try to think about why it doesn t look the same If you think it s because go remains pressed until you manually unpress it we ll fix that problem by the end of the tutorial Remember that we kept Autoplot on This allows the plot to readjust itself when it runs out of room a Turtles at Peaks Pens 39 6 a a E a z 0 0 Time 33 8 You might try running the model several times under different settings i e different values of smoothness and watch how fast the plot converges to some value and what fraction of the turtles make it to the top You may want to even try the same settings several times Some More Details There are a few quirks you may already have noticed Here are some quick changes you can make First we have a green landscape a naturally green turtle is going to be hard to see In the ask turtles block in setup turtles you can say if shade of green color set color red Second instead of always using 100 turtles you can have a variable number of turtles Make a slider variable say number 56 Tutorial 3 Procedures NetLogo 3 0 User Manual 000 Slider Global variable smoothness Minimum 0 Increment 0 1 Maximum 20 Value 8 Units optional Cancel Co
109. a ert 100 create 100 turtles ask turtles set color red turn them red rt random float 360 77 give them random headings fa 50 7 spread them around ask patches if pxcor gt 0 77 patches on the right side set pcolor green 5 Of the screen 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 Programming Guide 81 NetLogo 3 0 User Manual Usually the observer uses ask to ask all turtles or all patches to run commands You can also use ask to have an individual turtle or patch run commands The reporters turtle patch and patch at are useful for this technique For example to setup ca SEL 3 make 3 turtles ask turtle 0 tell the first one EL 77 to go forward ask turtle 1 tell the second one set color green 77 to become green ask turtle 2 tell the third one te 90 1 iF a tO burn Tight ask patch 2 2 7 ask the patch at 2 2 set pcolor blue 5 to become blue ask turtle 0 ask the first turtle ask patch at 1 0 7 to ask patch to the east set pcolor red to become red end Every turtle created has an ID number The first turtle created has ID 0 the second turtle ID 1 and so forth The turt le primitive reporter takes an ID number as an input and reports the turtle with that ID number The patch primitive reporter takes values for pxcor and pycor and reports the patch with th
110. a NetLogo 1 x model is read into NetLogo 2 0 or higher all uses of the random primitive are automatically converted to random int or float instead because the meaning of random has changed lt used to sometimes return an integer and sometimes a floating point number now it always returns an integer This primitive mimics the old behavior as follows If number is positive reports a random number greater than or equal to 0 but strictly less than number If number is negative the number reported is less than or equal to 0 but strictly greater than number If number is zero the result is always zero as well If number is an integer reports a random integer If number is floating point has a decimal point reports a floating point number show random int or float 3 jo prints 0 17 or 2 show random int or float 5 0 7 prints a number at least 0 0 but less than 5 0 7 for example 4 686596634174661 random n of 226 Primitives Dictionary NetLogo 3 0 User Manual random n of size agentset From an agentset reports an agentset of size size randomly chosen from the input set From an list reports a list of size size randomly chosen from the input set 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 random n of 50 patches set pcolor green 7
111. a 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 language 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 24 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
112. a ia Ia 153 Is NetLogo compiled or interpreted occccononococnncncccnnnnnononncnnnnnnnnnnnonnnncnnnnncnnnnnnnnnnnos 153 Will NetLogo and NetLogo 3D remain Separate cccconnonococcccncccnnnnononncnnnnnnonnnnnanononoos 153 DOWIMOAGIN Gis 2 eco A RAD ER Rio A canada 153 The download form doesn t work for me Can have a direct link to the software 154 Downloading NetLogo takes too long Is it available any other way such as ona A NE 154 downloaded and installed NetLogo but the Models Library has few or no models IE AOWsCan IICA ia ER 154 Can have multiple versions of NetLogo installed at the same time 154 I m on a UNIX system and can t untar the download WhY ccoooonococcccncccccccnonannnnnoos 154 How do install NetLogo on Windows 2003 or Windows Server 20032 154 ADDICTS da 154 tried to run one of the applets on your site but it didn t work What should do 155 Can make my model available as an applet while keeping the code secret 155 Can a model saved as an applet use import world file open and other commands Nata diles ica cnc 155 USC AAA Pah ned A ca 155 Canl r n Neilodo tom a CD ads da 156 How do change how many patches there are cccccccnnonococcccccccnnnnononnncnnnnnncnnnnanononnos 156 Can use the mouse to paint in the View cccconnnononccccnnnnccnnonannnnnnnnccnnnnnnnnonnnnnnnnnnns 156 How big can my model be
113. aico aaa 17 Macintosh onh Hug Sis A A cavyesda Dai Ud 17 Linux UNIX only UGS 2 cece cece cece cece ii ae eee aA dees seaeeeeeesseeeseeeeeeeseeeseeeeeeee 18 Known issues with computer HubNet ee eeeeeee eee ee teeta eee eeeeeaeeseneeeeeeeeseeeeeeeee 18 Unimplemented StarLogoT priMitiVES cocoooocccnnnncccnnnnoooonnonncccnonanonnnnncnnnnncnnnnnnnnnnnnnnccnnnnnos 18 Contacting Us A A 19 A E EE ED te Be Soe Ee Oo Cee DE ete Sen SM a aaa GRE A 19 Feedback Questions Ete is susiissisia ra a id 19 Reporting BUGS sse A vias ada dave att 19 Sample Model Paria caracas 21 ta Pary O 21 A O 23 Thinking A resent ane a mira dane adora da chdenanebaa suena Gos ada cea EE Eaa aae 24 MS A 24 NetLogo 3 0 User Manual Table of Contents Tutorial F1 ModelS O 25 Sample Model Wolf Sheep Predation errar aneaaaaaaarereaaananoa 25 Controlling the Model Buttons rior bie 26 Adjusting Settings Sliders and SWItCh8S cccccconnnononcccnnnonoconnnananonnncnccnnnnnnnnnncnnnnnnnnnnnnnnnnnos 27 Gathering Information Plots and MONItOFS ccconnnononcccnnnnnccnnnnanononnnnncnnnnnnnnnnnncnnnnnnnnnnnnnnnnos 29 PIOUS aire Sete a eC A Reece ti Sento 1 9 RT O 29 MONOS td tee 6 et Peder Ree Cina Maton ace et ee oes dae ek lee a dd 29 Controlling the MEN sanita A ES AA A id 29 The Models Library oi a taveave seen EE 33 sample Models ape 34 Curricular Models x setas Dietas rd it ias 34 MS OCG EXA O A E ASET 34 HubNet C
114. alculator 8 Computer ActIV tIOS ccoooocooccccncccnonanoconncncccnnnnannnononcnnnnnnnonnnnnnnos 34 Whats Next tit E A IN A Ra a aad 34 Tutorial 2 CommandS cuac a doli 35 sample Model Traffic Basica o 35 The Command Center a ereta ear ereta cano na rca nana a apa ada 35 Working With COS asirio ilatina 38 Agent Monitors and Agent COMMANUEeES cooooccccccnccccnononononcnnnncnnnnnnnnoncncncnnnnnnnnnnnrncnnnncnnannnnnnnss 40 VADE IEN ED AAA EAE E A EE ci pps Sha Do sga nda 43 Tutorial 43 ProceduUtOS iaa anctvavscsavadensussduwedeuaiscnatscbarsseuawetnauadedaianvarsceinsWehineens 45 SONANDO rs ni td a AA Ra ao 45 Patches MAN o Aa Edo 49 AURA OA e 52 Some More DelalS imei testa 56 Whats Next a E o A LE o A O DE ca a Ad IN 58 Appendix Complete Code insta as 58 Interface Guide iaa add 61 Menus 42 a e a do abr a be ae 61 Main WOON ssa iia o E De 63 Internac Tacna adi A A jade A A et 63 Procedures Tabs risa 69 INOrMatiOn Ida A A A E da dd AS DO a e 71 WHATIS IE a o SADO e RO DRDS RR RD E AR ARS NR NERO RR RR RR 73 Programming QuUIde a Da aa 75 AO da Seen A USA ca ASS DUE SRS UR O O CS o RARO NE ANE SR ESSO 75 A ns iso ica et SNL thas E E A A eae N E E eta E tole eek aaa SALA bale ta 76 AYE Tia 6 Xo Seem a A a RT a ENE RI A SO 77 Col Sica it dilo 79 AS A A A A e O NL Be gS A A UN 81 ADOOS iia 82 Beede IA RA A AA AA Beat a 84 A A tied et a O a da Mate ee ad alee teas Gane et ha lia hi ee eae a 85 SV ING ACN ZAMOR
115. alue 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 8 crt read from string user input Make how many turtles 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 listhas 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 22 1 2 3 gt 6 show reduce 1 22 1 2 3 gt 4 show reduce 2 1 1 2 3 gt 2 show reduce 1 1 2 3 gt show reduce 2 1 2 3 gt 3 show reduc sentence 1 272 1 2 3 4 5 gt 1 2 3 4 5 show reduce fput 2 1 Eput ITI 3 4 31 gt 5 4 3 2 1 Here are some more useful examples find the longest string in a list to report longest string strings 228 Primitives Dictionary NetLogo 3 0 User Manual report reduce ifelse valu length 1
116. an experiment SCI cintia ici leben 108 Running an experiment eee eeeeeeaaeaaaeaaae aaa aaana nana nana nana nananananana 110 Advanced MURT TO acacia 111 Running from the command ling escocia aiii aid ica idad 111 Setting up experiments in XML iu il 113 Control AP esrara ido 114 COCINA EEA E EAS TE E EE E E E EEEO A 114 AA AA 115 Understanding HubNet rare rear rena rear rre rre 115 NEILODO sacas gas sanear a A E SUE aaa Do E ER 115 HubNetArchieciure sn sacia io leo lid 115 Computer UDS 116 POVOS aroe a a Mech enc RS Dr ia aa fede Det Da alas Gattai adds Din atta iat De 116 Requiero DNA Dr TRE ERRO NR ben ME SARRO PDR DDR E des 116 NetLogo 3 0 User Manual Table of Contents HubNet Guide St rtingan AGtiVity aia O RP Sol cunt DR NRP SRD DE aes 116 HitibNet Control Center ss resinas tre as 117 Troubleshooting eee 117 KNONNULIMIANONS A AD ISSA Saba as Toa Ta 118 Calculator HUBNCE aia rata a Ponty doe t esa pda Sds dus SAT usado 119 REequIES MENS usa ida 119 Teacher workshops cnn nnn nn aren nn nnnnnnnnnnnnos 119 Hu bNet Autnornng Guide ia aida 119 Getting help orina DR RD RE RNP RR RR PR SR SRD tae yr 119 HubNet Authoring Guide 2 5 2 jastagai loca amanan sonia saca o as 121 General HubNet Information reter nono nonononananono nana er ea rar tara 121 NetL g Primitives is pe ssa ereta radar fade raias ead AA 121 SOU nn ete cour ori a e outeed wadeecourtanss 121 PAS E A
117. an 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 156 FAQ Frequently Asked Questions NetLogo 3 0 User Manual e Macintosh Edit the Contents 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 XX PrintJavaStackAtFatalState Xms16M Xmx512M 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 e 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 java Xmx512M jar NetLogo jJar Can I import an image into NetLogo Yes using the import pcolors and import drawing commands See Image Import Example in the Code Examples section of the Models Library Can import GIS data into NetLogo One simple way is to use import pcolors but that only works for importing
118. 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 Primitives Dictionary 197 NetLogo 3 0 User Manual 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 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 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
119. and returns 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 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 values from turtles xcor 7 prints the average of all the turtles x coordinates median median list 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 values from turtles xcor 7 prints the median of all the turtles x coordinates member member value list member string1 string2 For a list reports true if the given value appears in the given list otherwise reports false Primitives Dictionary 209 NetLogo 3 0 User Manual For a string reports true or false depending on whether string1 appears anywhere inside string2 as a substring show member 2 1 2 3 gt true show member 4 1 2 3 gt false show member rin string gt true See also_position min min list Reports the minimum number value in the list It ignores other types
120. ands 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 ppd for short If you want to plot individual points instead of lines or you want to draw bars instead of lines of 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 histogram 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 from command like this histogram from turtles age If the data you want to histogram don t come from an agentset but from a list of numbers use the histogram 1ist command instead Note that using the histogram commands 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
121. ass in order to maintain their energy when they run out of energy they die Once grass is eaten it will only regrow after a fixed amount of time This variation is more complex than the first but it is generally stable 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 Interface Procedures WHAT IS IT This model explores the stability of predator prey ecosystems The construction of this model is described in two papers by Wilensky amp Reisman referenced below Such systems are called unstable when they tend to result in extinction for one or more species involved In contrast systems are stable when they tend to maintain themselves over time despite fluctuations in population sizes There are two main variations to this model 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 WHAT IS IT 72 Interface Guide NetLogo 3 0 User Manual Lines that come after WHAT IS IT blank lines and contain capital letters and no lower case letters become section headers Any lin
122. atch at heading and distance patch at heading and distance heading distance P XE patch at heading and distance reports the single patch that is the given distance 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 set pcolor of patch at heading and distance 90 1 green 7 turns the patch 1 to the west of the calling patch E 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 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 set pcolor of patch right and ahead 30 1 green 7 the calling turtle looks 30 degrees right of its it current heading at the patch 1 unit away and turns aa that patch green note that this might be the same i patch the turtle is standing on See also patch
123. ating 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 up to that point When all the runs have finished the experiment is complete Advanced usage 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 Xmx512M cp NetLogo jar org nlogo headless HeadlessWorkspace model Fire nlogo xperiment experimentl After the named experiment has run the results are sent to standard output in CSV format If you want to send the results to a file instead add the results flag and a pathname e g java Xmx512M cp NetLogo jar org nlogo headless HeadlessWorkspace model Fire nlogo xperiment experimentl results results csv When running the HeadlessWorkspace class as an application it forces the sys
124. b based version of the Models Library and click on the name of the model An example model URL is http ccl northwestern edu netlogo models PepperedMoths To determine the year open the model from the NetLogo application and look in the copyright information at the bottom of the Procedures tab 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 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 evaluating how best to distribute NetLogo when it is in a more mature state Making the source available is one possibility FAQ Frequently Asked Questions 151 NetLogo 3 0 User Manual We do understand however that it is important that NetLogo not be a closed and non extensible platform That is not our intention for the product So for example NetLogo includes APIs so that NetLogo can be controlled from external Java code and users can write
125. ber report number end 244 Primitives Dictionary NetLogo 3 0 User Manual to report first turtle report who 0 reports true or false end towards towards nowrap towards agent towards nowrap agent Reports the heading from this agent to the given agent If the wrapped distance around the edges of the screen is shorter than the on screen distance towards will report the heading of the wrapped path towards nowrap never uses 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 towardsxy towardsxy nowrap towardsxy x y towardsxy nowrap x y Reports the heading from the turtle or patch towards the point x y If the wrapped distance around the edges of the screen is shorter than the on screen distance towardsxy will report the heading of the wrapped path towardsxy nowrap never uses the wrapped path Note asking for the heading to the point the agent is already standing on will cause a runtime error turtle turtle number Reports the turtle with the given ID number or_nobody if there is no such turtle number must be an integer set color of turtle 5 red 7 turtle with id number 5 turns red ask turtle 5 set color red 77 another way to do the same thing Primitives Dictionary 245 NetLogo 3 0 User Manual turtles turtles Reports the agentset consisting of all turtles show count turtles 7
126. ce 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 runExperimentFromMode1 is used when the experiment setup is already stored in the model file 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 runExperiment 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 Controlling Guide 137 NetLogo 3 0 User Manual 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 Optio
127. chnique 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 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 se
128. chool 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 MIES Edit Tools Zoon 8 4 New N tl 3 Open O Models Library 3M t mi tet it B Deleg Save 36S Save AS Save As Applet Print dE P 3 Open the Social Science folder 4 Click on the model called Party Sample Model Party 21 NetLogo 3 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 peopl
129. cifying 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 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 114 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 TI 83 calculator For example in the Gridlock simulation each 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 informati
130. d pen erase pe pen up pu 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 and setxy Note These commands are equivalent to setting the turtle variable pen mode to down up and erase pen mode 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 pen size x 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 plabel x 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 no label plabel color label label color Primitives Dictionary 221 NetLogo 3 0 User Manual plabel color plabel color El sk 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 labe
131. d from the shapes library or from other models in the Shapes Editor show shapes gt default airplane arrow box bug ask turtles set shape random 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 showturtle st showturtle The turtle becomes visible again Primitives Dictionary 239 NetLogo 3 0 User Manual Note This command is equivalent to setting the turtle variable hidden to false See also_hideturtle shuffle shuffle list Reports a new list containing the same items as the input list but in randomized order show shuffle gt 52 4 1 3 show shuffle gt 1352 4 123 4 5 123 4 5 sin sin number Reports the sine of the given angle Assumes angle is given in degrees show sin 270 gt 1 0 size size This is a built in turtle variable It holds a number that is the turtle s apparent size The default size is 1 0 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 Reports a new list containing the same items as the input list but in ascending order If there is at least one number in
132. d lower right quadrants turn blue Y Primitives Dictionary 255 NetLogo 3 0 User Manual ycor ycor This is a built in turtle variable It holds the current y coordinate of the turtle This is a floating point number not an integer You can set this variable to change the turtle s location This variable is always greater than or equal to screen edge y and strictly less than screen edge y See also_setxy xcor pxcor pycor 2 91 2 a 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 256 Primitives Dictionary
133. d port of your HubNet server which appear in the HubNet Control Center 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 HubNet Guide 117 NetLogo 3 0 User Manual particular networks that use the IPsec protocol typically do not support multicast The IPsec protocol is used on many virtual private networks VPN s When a participant tries to connect to my activity nothing happens after they click Enter 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 checkbox in the HubNet Control Center is selected e Make sure that the display switch in the model is on e The view on the server must be exactly the same size as on the client If you changed the size of the view on the HubNet server you need to restore it to its original dimensions There is no view on the HubNet client Some activities don t have a view on the client can t quit a HubNet client You will have to force the client to quit On OS X force quit the application by selecting Force Quit in the Apple menu On Windows press Ctrl Alt Delete to open the Task Manager select HubNet Client and pre
134. degrees not 350 degrees how subtract headings 80 60 gt 20 how subtract headings 60 80 gt 20 how subtract headings 5 355 gt 10 how subtract headings 355 5 gt 10 how subtract headings 180 0 gt 180 how subtract headings 0 180 gt 180 o lo o ia i wv il a sum sum list Reports the sum of the items in the list show sum values from turtles energy 7 prints the total of the variable energy 7 from all the turtles Primitives Dictionary 243 NetLogo 3 0 User Manual T tan tan number Reports the tangent of the given angle Assumes the angle is given in degrees 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 to to procedure name to procedure name input1 input2 Used to begin a command procedure to setup ca crt 500 end to circle radius ect 100 fd radius end to report to report procedure name to report procedure name input input2 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 end to report absolute value number ifelse number gt 0 report num
135. 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 Copyright Information 5 NetLogo 3 0 User Manual 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 Sun Microsystems Inc 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 Redistribution of source code must retain the above copyright notice this list of conditions and the following disclaimer e 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 DA
136. diting 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 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 Curricular Models Code Examples HubNet Calculator Activities HubNet Computer Activities Tutorial 1 Models 33 NetLogo 3 0 User Manual Sample Models The Sample Models section is organized by subject area and currently contains more than 180 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 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 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 yo
137. ds Example breeds cats dogs turtle code if breed cats show meow set breed dogs show woof breeds breeds breed1 breed2 This keyword like the globals turtles own and patches own keywords can only be used at the beginning of a program before any function definitions It defines breeds and their associated agentsets Any turtle of the given breed e is part of the agentset named by the 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 174 Primitives Dictionary NetLogo 3 0 User Manual The order in which breeds are declared is also the order in which they are drawn in the 2D view So breeds defined later will appear on top of breeds defined earlier breeds mice frogs to setup ca create mice 50 ask mice set color white create frogs 50 ask frogs set color green show breed of one of mic 7 prints mice show breed of one of frogs 7 prints frogs end See also globals patches own turiles own lt BREED gt own create lt BREED gt create custom lt BREED gt lt BREED gt at lt BREED 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 la
138. ds 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 of the runs to be controlled by the stop condition instead enter 0 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 tick according to the setting of Measure runs at every tick 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 experime
139. e Can run a NetLogo model from the command line Can run it without a GUI Yes If you set up your model run or runs as a BehaviorSpace experiment then you can run the experiment from the command line No additional programming is required See the BehaviorSpace section of the User Manual for details If you don t use the BehaviorSpace method then you can still run NetLogo from the command line and or with no GUI using our Controlling API Some light Java programming is required See the Controlling section of the User Manual for details and sample 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 ina 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 Macs you ll need to duplicate the application in the Finder then open the copy This will use only a very small amount of additional disk space since most of NetLogo is actually in the NetLogo jar file which is stored outside the application bundle 158 FAQ Frequently Asked Questions NetLogo 3 0 User Manual Can save the contents of the view Of the interface tab Yes using Export View on the File menu or by right clicking on Mac control clicking the view or using the export view command Both methods work for either the 2D and 3D view whichever is Curre
140. e create cats 1 7 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 and automatically Change their shape to dog See also_shape set histogram num bars set histogram num bars integer Set the current plot pen s plot interval so that given the current x range for the plot there would be integer number of bars drawn if the histogram from or histogram list commands were called See also histogram from 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 from and histogram list commands set plot pen mode Primitives Dictionary 237 NetLogo 3 0 User Manual set plot pen mode number Sets the mode the current plot pen draws in to number The allowed plot pen modes are e O line mode the plot pen draws a line connecting two points together e 1 bar mode the plot pen draws a bar of width plot 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 mod
141. e We can rewrite it as follows patches own elevation to setup ca setup patches setup turtles end The line at the top patches own elevation declares that we have a variable for the patches called elevation Our setup patches procedure that we haven t defined yet will then use this variable We also still need to define setup turtles as well but for now here s how to define setup patches to setup patches ask patches set elevation random 10000 diffuse elevation 1 ask patches set pcolor scale color green elevation 1000 9000 end Tutorial 43 Procedures 49 NetLogo 3 0 User Manual The setup patches procedure sets the elevation and color of every patch First each patch picks a random integer between 0 and 9999 and sets its e evation variable to that number We then use an observer primitive diffuse that smooths out the distribution of this variable over the neighboring patches Remember that primitives are built in procedures in NetLogo as opposed to procedures that you define Scale color is a reporter that uses the different values of elevation to assign colors to the patches In this case we re assigning different shades of green to all the patches Don t worry about the numbers given to diffuse and scale color just yet The larger e evation is the lighter the shade of green Low values of elevation will result in darker shades The only part remaining in our new setup that is still undefined
142. e 25 or so Then change your code to repeat smoothness diffuse elevation 1 Experiment with the turtles performance in different terrains We still haven t even begun to solve the problem of getting all the turtles to the highest elevation though So far we ve just been getting the turtles to the highest point that s near them If a turtle starts off in one corner of the world on a hill and there s a mountain in a different corner the turtle will never find the mountain To find the mountain the turtle would have to go down off the hill first but in our model turtles only move up Notice that the individual turtles don t use highest anywhere The turtles just look at elevations close to them and go the highest point they can see Before trying something else it d be nice if we could have some other more precise method for evaluating the turtles performance Fortunately NetLogo allows us to plot data as we go along 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 Let s do the Procedures tab part first Change go to call the new procedure we re about to add to go move to local max do plots end Now add the new procedure What we re plotting is the number of turtles who ve reached our peak zone within 1 of the highest elevation at some given time to do plots set current plot
143. e caller itself if it s a turile ca 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 breeds cats dogs create cats 5 create dogs 1 ask dogs show count cats here See also_other turtles here turtles on BREED on turtles on agent turtles on agentset BREED on agent BREED 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 fd 1 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 See also_turtles from Primitives Dictionary 247 NetLogo 3 0 User Manual turtles own BREED own turtles own var1 var2 BREED own var1 var2 The turtles own keyword like the globals breed lt BREED 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 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 breeds cats dogs hamsters turtles own eyes legs 7 applies to all breeds cats own fur kittens hamster
144. e described in ti Disease client nlogo in the clients subdirectory of the model d This primitive must be called before you use any other HubNet primitives including hubnet reset so NetLogo knows which type of HubNet you are going to be using 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 HubNet remains running as long as this model is open it stops running when the model is closed or you quit NetLogo HubNet Authoring Guide 121 NetLogo 3 0 User Manual If you are using Computer HubNet you will be prompted for a session name This is an identifier to make servers discovered by the client uniquely identifiable These primitives are usually called from the startup procedure rather than set up of the NetLogo model since they should only be called once in a model Data extraction During the activity you will be transferring data between the HubNet clients and the server The following primitives allow you to extract data from the clients hubnet message waiting This looks for new information sent by the clients It reports TRUE if there is new data and FALSE if there is not 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 This will cause an error if there is no new data from the clients So be sure to c
145. e 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 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 setxy 0 0 7 turtle moves to the middle of the center patch 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 238 Primitives Dictionary NetLogo 3 0 User Manual shape shape This is a built in turtle variable It holds a string that is the name of the turtle s current shape You can set this variable to change a turtle s shape New turtles 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 Shapes Editor See also set default shape shapes shapes shapes Reports a list of strings containing all of the turtle shapes in the model New shapes can be created or importe
146. e in the center of the patch The world of patches isn t bounded but wraps so when a turtle moves past the edge of the world it disappears and reappears on the opposite edge 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 Procedures In NetLogo commands and reporters tell agents what to do Commands are actions for the agents to carry out Reporters carry out some operation and report a result either to a command or another reporter Commands and reporters built into NetLogo are called primitives The Primitives 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 ca 7 clear the screen ere 10 make 10 new turtles end to go ask turtles fd 1 7 all turtles move forward one step rt random 10 jj 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 this program e
147. e 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 agent is the focus you can use the subject reporter Code Example Perspective Example Turtle Pens In past versions of NetLogo when turtles had their pen down they changed the pcolor of the patch below them We have improved NetLogo s support for drawing as in more traditional logos Turtles have by default a one pixel wide pen that draws or erases in a separate layer between the turtles and the patches Turtles draw in their own color The the size of the pen is variable and can be set using the pen si ze turtle variable Turtles can stamp an image of their current shape into this layer using the stamp command To remove lines and stamps turtles need only to switch to pen erase mode using the pe command You can import images directly into the drawing using the import drawing command There are still some features present in many logos but not in NetLogo and some features work differently in NetLogo Features that are not supported e flood color or fill fill the enclosed area with the pen color
148. e of the model to the file fire csv located in the NetLogo folder export plot Temperature c My Documents plot csv 7 exports the plot named Temperature to the file plot csv located in 77 the C My Documents folder 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 0 to 1 0 representing the hue saturation and brightness respectively of the given NetLogo color in the range 0 to 140 show extract hsb red gt 0 0 1 0 1 0 show extract hsb cyan gt 0 5 1 0 1 0 See also hsb rgb extract rgb extract rgb extract rgb color Reports a list of three values in the range 0 0 to 1 0 representing the levels of red green and blue respectively of the given NetLogo color in the range 0 to 140 show extract rgb red gt 1 0 0 0 0 0 show extract rgb cyan gt 0 0 1 0 1 0 See also rgb hsb extract hsb F 186 Primitives Dictionary NetLogo 3 0 User Manual face face nowrap face agent face nowrap agent Set the caller s heading towards agent If the wrapped distance around the edges of the screen is shorter than the on screen distance face will use the heading of the wrapped path face nowrap never uses the wrapped path If the caller and the agent are at the exact same position the caller s heading won t change facex
149. e 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 outcome 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 m
150. e 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 the pipe shift backslash become monospaced text This is useful for diagrams and complicated formulas among other things this is preformatted text this is preformatted text you can put spacesin it you can put spaces in it To return to the normal view click the edit button Interface Guide 73 74 NetLogo 3 0 User Manual Interface Guide Programming Guide The following material explains some important features of programming in NetLogo Note If you are already familiar with StarLogo or StarLogoT then the material in the first four sections may already be familiar to you The Code Example models mentioned throughout can be found in the Code Examples section of the Models Library e Agents e Procedures e Variables e Colors e Ask e Agentsets e Breeds e Synchronization e Buttons e Lists e Math e Random Numbers e Turtle Shapes e Plotting e Strings e Output e File I O e Movies e Perspective e Turtle Pens 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
151. e 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 very 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 22 Sample Model Party NetLogo 3 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 opposit
152. e will not cause runtime errors but will produce 90 Programming Guide NetLogo 3 0 User Manual incorrect answers Floating point numbers are numbers containing a decimal point In NetLogo they operate according to the IEEE 754 standard for double precision floating point numbers These 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 Any operation which produces the special quantities infinity or not a number will cause a runtime error In NetLogo integers and floating point numbers are interchangeable in the sense that as long as you stay within legal ranges it is never an error to supply 3 when 3 0 is expected or 3 0 when 3 is expected In fact 3 and 3 0 are considered equal according to the equals operator If a floating point number 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 Scientific notation Very large or very small floating point numbers are displayed by NetLogo using scientific notation Examples O gt show 0 000000000001 observer 1 0E 12 O gt show 50000000000000000000 0 observer 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 O gt show 1 0
153. eceeecceecaeeceeeceeceeeceseceeeeeeeeeeeeeeeeeeess 198 nubnet MESSI Sii a ic ada 198 hubnei message waitina Pira A ae aa 198 A eA et Ae ete eit A Ae Lee ee 199 A E UR EE dial de NR 199 NUDNET SENG VICW cee ccececccseeceeeeceeseceeeceeeeeeceeeeueeeeueessueeeceeeeseueeseeueeseueeseueeseeueeseeeesenees 199 hubnet sei client interTace occcconionicnccnnncocicinancnnco nan cnncn nan cn cnc nana cananea dare 200 da Mets a ns O dd e a ate or tod ao ato ate ale 200 Mt ida 200 HO ia A A a eda Daiana 200 felse Vvalle art ta ti local oes 201 IMPONE ltet ilate MERE E E E A E E E EE 201 IMPOM DCOlONS FER AE AE EEE A E E EEA E 202 IMP OM SWOFl 6 K A o 202 in cone IN CONEC NOWLAD cccccccsccececeeeceaeeeeceeeceeecenecesecenecececcaeceecceeceeeeeeeeeeeeseeeeeeesenes 202 in radius IN FAQIUS DQWIAD coccconccnncnonnnonnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnneinnenss 203 Odia iekaesin 203 Mia da ads 204 is agent is agentset is boolean is list is number is patch is patch agentset is string is turtle is turtle agentset s 204 a TN 204 VA A IA A A a Datla 205 A cei elects a a ges ote tcc ge RE RR RIR OR RR E 205 O A NRO 205 ADO tt ad tr 205 E 205 A es 206 Sila dc AA O A A A A AO A Atos 206 tii daa 206 leta A TA 206 BR A E RNA 207 i a E A o da DEE ek e a a oa eo Mie aba at 207 1 m PE EE E A OA 207 Dr aora 207 Orar as 208 A A cane eae ts ce asec Sa aca 208 AF
154. ecific 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 Modeling 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 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 documentatio
155. ed 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 O gt in the bottom left corner Command Center Wi Clear observer gt ask patches set pcolor yellow observer gt ask turtles set color brown obser v observer j patches e Ta Key Tutorial 2 Commands 37 NetLogo 3 0 User Manual e Choose Turtles from the popup menu e Type set color pink and press return e Press the tab key until you see P gt in the bottom left corner e Type set pcolor 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 The observer oversees the world and therefore can g
156. ed 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 foreach command and the map reporter may be helpful foreach is used to run a command or commands on each item in a list It takes an input list and a block of commands like this foreach 2 4 6 ert lt 2 show 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 Programming Guide 89 NetLogo 3 0 User Manual foreach 1 2 3 ask turtles fd 5 turtles move forward 6 patches foreach true false true true ask turtles if fd 1 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 pp 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
157. ed 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 NetLogo uses the MRJ Adapter library which is Copyright c 2003 Steve Roy lt sroy roydesign net gt 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 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 http Awww gnu org copyleft lesser html 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 For movie making NetLogo u
158. edation 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 view you ll see a strip of controls along the top edge The control strip lets you control various aspects of the view Tutorial 1 Models 29 NetLogo 3 0 User Manual 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 slider in the control strip back and forth 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 all the way to the right again e Now try pressing and unpressing the red arrowhead in the control strip e Also try pressing and unpressing the on off switch in the control strip What happens The shapes button and the freeze button are useful if you re impatient and want a model to run faster When shapes are turned
159. edures read Tutorial 3 Procedures and the Programming Guide 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 you re first exploring a model Interface Guide 71 NetLogo 3 0 User Manual Interface Procedures Y Find Edit This model explores the stability of predator prey ecosystems The construction of this model is described in two papers by Wilensky amp Reisman referenced below Such systems are called unstable when they tend to result in extinction for one or more species involved In contrast systems are stable when they tend to maintain themselves over time despite fluctuations in population sizes There are two main variations to this model In the first variation wolves and sheep wonder 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 population to continue each wolf or sheep has a fixed probability of reproducing at each time step This variation produces interesting population dynamics but is ultimately unstable The second variation includes grass green in addition to wolves and sheep The behavior of the wolves is identical to the first variation however this time the sheep must eat gr
160. elation to the xy plane will change To move closer or farther away from the world 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 Interface Guide 67 NetLogo 3 0 User Manual 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 circle sphere square cube triangle cone cylinder 3D cylinder car All other shapes are i
161. end up needing the highest and lowest elevation in several places in our procedures let s make a shortcut We ll do a little extra work now so that if we need these values later we ll have a shortcut to use First at the top of your code right after the patches own declaration declare two global variables as such globals highest the highest patch elevation lowest the lowest patch elevation Notice the use of semicolons here Although the names of the global variables are descriptive the semicolons allow us to describe the variables even more Global variables can be used by all the agents in the model In particular patches can use highest and lowest in the setup patches procedure We need to store the highest and lowest elevations in these global variables once and then everyone will have quick access to them after Tutorial 3 Procedures 51 NetLogo 3 0 User Manual that Write to setup patches ask patches set elevation random 10000 diffuse elevation 1 ask patches set pcolor scale color green elevation 1000 9000 set highest max values from patches elevation set lowest min values from patches elevation ask patches if elevation gt highest 100 set pcolor white if elevation lt lowest 100 set pcolor black end Now we have saved the highest and lowest points in our terrain and displayed them graphically Look at the last two commands the if commands Each patch when it runs
162. eports a string with the absolute file path or false if the user cancels Note that no file is ever created or overwritten with this reporter file open user choose new fil Assumes the user will choose a file 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 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 There are count turtles turtles user yes or no user yes or no value Reports true or false based on the user s response to value 250 Primitives Dictionary NetLogo 3 0 User Manual value may be of any type but is typically a string if user yes or no Set up the model setup V value from value from agent reporter Reports the value of the reporter for the given agent turtle or patch show value from turtle 5 who who gt 25 show value from patch 0 0 count turtles in radius 3 7 prints the number of turtles located within a 7 three patch radius of the origin values from values from agentset reporter Reports a list that contains the value of the reporter for each agent in the agentset ca crt 4 show values from turtles who gt 0 1 2 3 show values from turtles who who gt 0 1 4 9
163. equences e n newline e t tab e double quote e backslash Programming Guide 97 NetLogo 3 0 User Manual 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 Primitives Dictionary Here is 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 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 t
164. erent ffom output port reverse because thisway and thatway will always be the same direction provided the connector s polarity is the same talk to output poris 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 output port on and 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 d 142 NetLogo GoGo Extension NetLogo 3 0 User Manual Examples 7 talk to all output ports talk to output ports a b er waw 7 will give power to all output ports output port on 7 talk to output ports A and D talk to output ports a d 7 will turn off output ports A and D The other output ports will keep their current state output port off talk to output ports c b 5 turn off remaining output ports output port off ping 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 show ping sensor sensor sensor Reports the value of the sensor named sensor as a number Sensors are named by numbers 1 to 8 Value ranges between 0 1023 1023 is returned when
165. es show cos 180 gt 1 0 count count agentset Reports the number of agents in the given 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 turtles crt create lt BREED gt create turtles number create lt BREED gt number o 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 crt 100 ask turtles fd 10 makes an evenly spaced circle If the create lt BREED gt form is used the new turtles are created as members of the given breed create custom turtles cct create custom lt BREED gt cct lt BREED gt 178 Primitives Dictionary NetLogo 3 0 User Manual create custom turtles number commands create custom lt BREED gt number commands io Creates number new turtles of the given breed if specified New turtles start at position 0 0 New turtles are created with the 14 primary colors and have headings from 0 to 360 evenly spaced The new turtles immediately run commands This is useful for giving the new turtles a different color heading or whatever breeds canaries snakes to setup ca create custom canaries 50 set color yellow create custom snakes 50 set color green end Note While the commands are running no other agents are allowed to run any code as
166. es For example the sprout command creates turtles with random colors and headings and the downhi 11 reporter chooses a random patch when there s a tie These random choices are governed by the random seed as well so model runs can be reproducible 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 pixels 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 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 random one of shapes Use the 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 Code Examples Breeds and Shapes Example Shape Animation Example Programming Guide 93 NetLogo 3 0 User Manual Plotting NetLogo s plotting features let you create
167. et broadcast primitives take a number a string a list of numbers or a matrix a list of lists of numbers as the value input When using Computer HubNet you may send any kind of information with the exceptions of patches turtles and agentsets Here are some examples of using the two primitives to send various types of data that you can send data type hubnet broadcast example hubnet send example t broadcast A 3 14 t send Jimmy A 3 14 t broadcast STRI1 E send 12 MISTA STR HERE I HERE t broadcast L2 as cues t message source L2 1 2 et broadcast et send Suzy A 1 2 3 4 11 et broadcast ubnet send teacher user names jimmy user names Jimmy suzy suzy 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 with which to start Calculator HubNet Information The calculators are able to send and receive the following data types from NetLogo e Valid calculator lists such as 1 1 or PLOTS e Valid calculator matrices such as A or B e Valid calculator strings such as Str1 or Str5 e Numbers such as A or B The length of the list of numbers that a calculator sends depends on what inf
168. f 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 be 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 and the
169. f other nobody set color of other red not Primitives Dictionary 215 NetLogo 3 0 User Manual not boolean Reports true if boolean is false otherwise reports false if not color blue fd 10 7 all non blue turtles move forward 10 steps nsum nsum4 nsum patch variable nsum4 patch variable st La For each patch reports the sum of the values of patch variable in the 8 surrounding patches nsum or 4 surrounding patches nsum4 Note that nsum nsum4 are equivalent to the combination of the sum values from and neighbors neighbors4 primitives sum values from neighbors var does the same thing as nsum var sum values from neighbors4 var does the same thing as nsum4 var Therefore nsum and nsum4 are included as separate primitives mainly for backwards compatibility with older versions of NetLogo which did not have the neighbors and neighbors4 primitives See also neighbors neighbors4 O of VARIABLE of agent Reports the value of the VARIABLE of the given agent Can also be used to set the value of the variable show pxcor of random one of patches 7 prints the value of a random patch s pxcor variable set color of random one of turtles red 7 a randomly chosen turtle turns red ask turtles set pcolor of patch at 1 0 red 7 each turtle turns the patch on its left red one of 216 Primitives Dictionary NetLogo 3 0 User Manual one of agentset If given a tu
170. f steps in the direction of its heading The steps are the same size as the patches end completes the definition of the setup procedure When you re done typing in the code switch to the Interface tab and press your setup button You will see the turtles quickly spread out in a rough cluster Notice the density distribution of the turtles in the view Press setup a couple more times and watch how the turtles arrangement changes Keep in mind that some turtles may be right on top of each other Can you think of other ways to randomly distribute the turtles over the screen Note that if a turtle moves off the screen it wraps that is comes in the other side Make a forever button called go Again begin by creating a button but this time check the forever checkbox in the edit dialog Tutorial 3 Procedures 47 NetLogo 3 0 User Manual Ta f w setup go 606 Button Agent s Observer 9 Forever Commands go Display name Action key Y Force view update after each run Checking this box produces smoother animation but may make the button run more slowly Cancel OK Then add its procedure to the Procedures tab to go move turtles end But what is move turtles Is it a primitive in other words built in to NetLogo like fd is No it s a procedure that you re about to write right after the go procedure to move turtles ask turtles set heading random 360 fd 1 e
171. fied 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 TI 83 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 user 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 Individual 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 MacOS Windows Linux et al e Language Fully programmable Simple language structure Language is Logo dialect extended to support agents and concurrency Unlimited numbers of agents and variables Many built in primitives Integer and double precision floating point math Runs are exactly reprod
172. ge exclusive interaction between agents For example turtles own mate to setup ask turtles set mate nobody end to find mate turtle procedure without interruption if mate nobody let candidate random one of other turtles her with mate nobody if candidate nobody set mate candidate set mate of candidate self end Using without interruption ensures that while a turtle is choosing a mate all other agents are frozen This makes it impossible for two turtles to choose the same mate I tried to put at after the name of a variable for example variable at 1 0 but NetLogo won t let me Why not This syntax was supported by StarLogoT and some beta versions of NetLogo but was removed from NetLogo 1 0 Instead for a patch variable write e g pcolor of patch at 1 0 and fora turtle variable write e g color of one of turtles at 1 0 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 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 FAQ Frequently Asked Questions 163 NetLogo 3 0 User Manual 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 patc
173. h So for example if turtle 0 nobody You could also use is turtle if is turtle turtle 0 How do find out how much time has passed in my model NetLogo does not automatically keep track of this If you want to keep track of the passage of time add a global variable to your model with a name like clock or steps In your setup procedure set the variable to O In your go procedure increment the variable Many of the models in the Models Library use this technique The reason NetLogo doesn t automatically keep track of this is that NetLogo is very flexible about letting you make buttons that do anything that you want them to NetLogo has no one way of knowing which of your buttons should advance the clock and which shouldn t Does NetLogo have arrays What NetLogo calls lists are actually implemented internally as arrays so they have some of the performance characteristics of arrays For example random access using the item reporter takes constant time However they re immutable arrays they cannot be altered except by making a copy and altering the copy so replace item is linear time not constant time because the whole array is copied For most purposes the performance differences between lists and arrays doesn t matter it only matters if you re dealing with very long lists In a future version of NetLogo we plan to change our lists to be ordinary singly linked lists as in other Logo and Lisp im
174. h 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 different 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 relation
175. h the top row If you ask a different agentset besides the set of all turtles or patches or a breed then the execution order will vary according to how the agentset was constructed The execution order is chosen deterministically and reproducibly though and will remain the same if you ask the same agentset multiple times In a future version of NetLogo we plan to add an option for randomized scheduling Once scheduled an agent s turn ends only once 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 or patch variable Setting a local variable doesn t count To prolong an agent s turn use the without interruption command The command blocks inside some commands such as cct and hatch have an implied without interruption around them NetLogo s scheduling mechanism 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 In general we suggest you write your NetLogo code so that it does not depend on a particular scheduling mechanism We make no guarantees that the scheduling algorithm will remain the same in future versions 166 FAQ Frequently Asked Questions Primitives Dictionary ABCDEFGHIJLMNOPRSTUVWXY Categories Turtle Patch Agentset Color Control Logic World Perspective Input Output Files
176. 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 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 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 m
177. have arrays e Does NetLogo have associative arrays or lookup tables e How can convert an agentset to a list or vice versa e What if want to ask an agentset in random order e How does NetLogo decide when to switch from agent to agent when running code General Why is it called NetLogo The Logo part is because NetLogo is a dialect of the Logo language 150 FAQ Frequently Asked Questions NetLogo 3 0 User Manual Net is meant to evoke the decentralized interconnected nature of the phenomena you can model with NetLogo It also refers to HubNet the networked participatory simulation environment included in NetLogo What programming language was NetLogo written in NetLogo is written entirely in Java version 1 4 1 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 an academic publication Wilensky U year Name of Model URL of model Center for Connected Learning and Computer Based Modeling Northwestern University Evanston IL To determine the URL for a model visit our we
178. he 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 oe tax Button Buttons can be either once only buttons or forever buttons When you click on a once button it executes its 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 64 Interface Guide NetLogo 3 0 User Manual the white background of the Interface tab Slider Sliders are global variables which are accessible by all agents They are used in models as a quick way to change a variable wit
179. he 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 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 184 Primitives Dictionary NetLogo 3 0 User Manual 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 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 and y values of all points plotted by all the plot pens in the plot given by the st
180. heck for data with hubnet message wait ing before calling this hubnet message source This reports the user name of the client that sent the data This will cause an error if no data has been fetched So be sure to fetch the data with hubnet fetch message before calling this hubnet message tag This reports the tag that is associated with the data that was sent For Calculator HubNet this will report one of the variable names set with the hubnet set client interfac primitive For Computer HubNet this will report one of the Display Names of the interface elements in the client interface See_below for more information about the Computer HubNet tags For both types of HubNet this primitive will cause an error if no data has been fetched So be sure to fetch the data with hubnet fetch message before calling this hubnet message This reports the data collected by hubnet fetch message This will cause an error if no data has been fetched So be sure to fetch the data with hubnet fetch message before calling this There are two additional data extraction primitives that are only used in Computer HubNet models hubnet enter message Reports true if a new computer client just entered the simulation Reports false otherwise hubnet exit message Reports true if a new computer client just exited the simulation Reports false otherwise For both hubnet enter message and hubnet exit message hubnet message source will c
181. hin 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 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 model 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 28 Tutorial 1 Models NetLogo 3 0 User Manual Note in addition to sliders and switches some models have a third kind of setting called a c
182. hink of the patches as being like square tiles in a room with a tile floor Exactly in the middle 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 distance the middle tile is from the right or left edge of the room this is called Screen Edge X And the distance the middle tile is from the top and bottom edges is called Screen Edge Y 0 0 Screen Edge X Screen Edge X 32 Tutorial 1 Models NetLogo 3 0 User Manual Screen Edge Y 0 0 Screen Edge Y In these diagrams Screen Edge X is 3 and Screen Edge Y 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 Screen Edge X and Screen Edge Y e Using the Edit dialog that is still open change Screen Edge X to 30 and Screen Edge Y value to 10 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 again e Change the patch size to 20 and press OK What happened to the size of the view Did its shape change E
183. his variable a turtle s id number never changes 252 Primitives Dictionary NetLogo 3 0 User Manual When NetLogo starts or after you use the clear all or clear turtles commands new turtles are created with ids in order starting at O If a turtle dies though a new turtle may eventually be assigned the same id number that was used by the dead turtle Example show values from turtles with color red who 7 prints a list of the id numbers of all red turtles in the Command Center ca ect 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 id 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 patches 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
184. hooser 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 ina 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 It saves this information to your computer in a format that can by read back by spreadsheet and database programs such as Excel You can also export a plot by 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 Pr
185. hout having to recode the procedure every time Instead the user moves the slider to a value and observes what happens in the model Ig 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 mi Chooser mi chooser Choosers let the user choose a value for a global variable from a list of choices presented in a drop down menu RS 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 update several times per second Plots are real time graphs of data the model is generating 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 E Text Text boxes lets you add informative text labels to the Interface tab The contents of text boxes do not change as the model runs The 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 e Edit 3D There are a number of settings associated with the Views There are a few
186. ice 50 set color white set cheese random 10 create custom frogs 50 set color green 84 Programming Guide NetLogo 3 0 User Manual end Code Example Breeds and Shapes 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 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 ac
187. ide NetLogo 3 0 User Manual a lighter shade of orange Code Example Scale color Example shows you how to use the scale color reporter For many models the NetLogo color system is a convenient way of expressing colors But sometimes you d like to be able to specify colors the conventional way by specifying HSB hue saturation brightness or RGB red green blue values The hsb and rgb primitives let you do this extract hsb and extract hsb let you convert colors in the other direction Since the NetLogo color space doesn t include all hues hsb and rgb can t always give you the exact color you ask for but they try to come as close as possible Code Example You can use the HSB and RGB Example model to experiment with the HSB and RGB color systems Ask NetLogo uses the ask command to specify commands that are to be run by turtles or patches All code to be run by turtles 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 and the observer except that code to be run by the observer must not be inside any ask Here s an example of the use of ask syntax in a NetLogo procedure to setup c
188. ides an implementation of the Java Communications API for Windows which you can download Once downloaded extract the files into a temporary directory Several files need to be copied into your Java Runtime Environment or JRE installation If you are using the version of NetLogo which comes with its own Java VM then your JRE installation is in the jre subdirectory of the NetLogo folder Otherwise it is in a directory like c 132sdk1 4 The files comm jar and javax comm properties must be copied into the 1ib folder of the JRE installation The files win32comm d11 must be copied to the bin folder of the JRE installation The file Plat formSpecific has more detailed instructions Linux and others There is no official implementation of the Java Communications API for Linux You can use the RXTX implementation Kevin Hester has written some installation instructions Using the GoGo Extension The GoGo Extensions comes pre installed To use the extension in your model add a line to the top of your procedures tab extensions gogo jar After loading the extension see what ports are available by typing the following into the command center show 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 show ping On Linux gogo open dev ttyS01 show ping For more informatio
189. if display 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 screen 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 taken 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 red turtles to appear briefly There is exception to the immediately rule if the command is used by an agent that is running without interruption such as via the without interruption command inside a procedure defined using to report or inside a command such as hatch sprout or cct then the view update takes place once the agent is done running without interruption 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 x 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 Primitives Dictionary 181 NetLog
190. igh 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 x The turile dies if xcor gt 20 die all turtles with xcor greater than 20 die See also ct diffuse diffuse patch variable number is 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 Note that this is an observer command only even though you might expect it to be a 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 77 each patch gets 1 8 of 50 of the chemical 7 from each neighboring patch diffuse4 diffuse4 patch variable number Like diffuse but only diffuses to the four neighboring patches to the north south east and west not to the diagonal neighbors 180 Primitives Dictionary NetLogo 3 0 User Manual diffuse4 chemical 0 5 7 each patch diffuses 50 of its variable 77 chemical to its neighboring 4 patches Thus 77 each patch gets 1 4 of 50 of the chemical from each neighboring patch display display Causes the current view to be updated immediately Also undoes the effect of the no display command so that
191. ight 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 23 NetLogo 3 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 system 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 phenomen
192. interpreted as relative to the location of the model just as in the application the rgb and hsb reporters are now better at choosing colors fixed histogramming bug where sometimes a value was assigned to the bar one to the left of the correct bar fixed bug that could cause a runtime error to be reported as happening in the wrong place in the code or to the wrong agent 4 fixed bug where is turtle and is agent sometimes returned true even if the input was nobody if a turtle died fixed Windows only problem where the sound extension didn t always work on some Java VM s newer than 1 4 2 05 import and export world now include the observer perspective and contents of the output area the sizing and positioning of turtle shapes in 2D especially very small ones is now more accurate and more consistent cross platform e interface fixes right control clicking to pick a turtle in the 2D view is now much easier because it takes the size and position of the turtle into account removed now useless checkbox for turning off Exact turtle positions amp sizes smaller changes in turtle heading are now visible onscreen particularly when the patch size is large turtle sizes 1 5 and 2 0 are now accelerated graphically in the 2D view before only size 1 0 was accelerated improved some error messages and improved the pinpointing of runtime error locations you can now use the keyboard shortcuts for undo and redo when editing the code in a bu
193. into your Java code 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 Plotting primitives are non functional However calling them will not produce any ill effects e The movie primitives are not available trying to use them will cause a Java exception e user primitives which query the user for input such as user yes or no will cause a Java exception e Sliders switches and choosers do not enforce constraints on the values they accept For example in the full NetLogo application if you try to set a switch to a value other than true or false the switch will not accept the new value Similarly a chooser enforces that its value is a valid choice and a slider enforces that its value is permitted by its minimum maximum and increment When running headless none of these checks occur We plan to lift these restrictions in a future version of NetLogo 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 BehaviorSpa
194. irectly 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 0 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 224 Primitives Dictionary NetLogo 3 0 User Manual Note In versions of NetLogo prior to version 2 0 this primitive reported a floating point number if given a floating point input This is no longer the case If you want a floating point answer you must now use random float instead show random 3 ap PEINCS 0 1 or 2 show random 3 i7 prints 0 1l or 2 show random 3 0 7 prints 0 1 or 2 show random 3 5 77 prints O 1 2 or 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 0 0 but strictly less than number If number is negative reports a random floating point number less than or equal to 0 0 but strictly greater than number If number is zero the result is always 0 0 show random float 3 7 prints a number at least 0 0 but less than 3 0 7 for example 2 589444906014774 show random float 2 5 7 prints a number at least 0 0 but less than 2 5 7 for example 1 0897423196760796 random exponential random gamma random normal random pois
195. irectly in a future version of NetLogo How can I convert an agentset to a list or vice versa Here s how to convert an agentset to a list of agents values from lt agentset gt self And here s how to convert a list of agents to an agentset turtles patches with member self lt list gt For a discussion of the whole issue of agentsets versus lists of agents see e http groups yahoo com group netlogo users message 652 e http groups yahoo com group netlogo users message 655 e http groups yahoo com group netlogo users message 656 What if want to ask an agentset in random order This is possible but the code for it is a bit awkward foreach shuffle values from lt agentset gt self ask E rasa eh i First values from converts the agentset into a list of agents Then shuffle randomizes the order of that list Finally foreach is used to walk through the list asking each agent in term The question mark is used with foreach to refer to the current item in the list We plan to support this more directly in a future version of NetLogo How does NetLogo decide when to switch from agent to agent when running code If you ask turtles or ask a whole breed the turtles are scheduled for execution in ascending FAQ Frequently Asked Questions 165 NetLogo 3 0 User Manual order by ID number If you ask patches the patches are scheduled for execution by row left to right within each row and starting wit
196. itives Dictionary NetLogo 3 0 User Manual See also follow foreach foreach list commands foreach list listn 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 gt round gt ll gt 1 gt 2 2 gt 2 gt 240 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 2n to refer to the current item of each list Some examples make this clearer foreach 1 2 3 2 4 6 show the sum is 21 2 1 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 If number is negative the turtle moves backward Turtles using this primitive can move a maximum of one unit per time increment So fd 0 5 and fd 1 both take one unit of time but fad 3 takes three See also jump fput fput item list Adds item to the beginning of a list and reports the new list Primitives Dictionary 193 NetLogo 3 0 User Manual 7 suppose mylist is 5 7 10 set mylist fput 2 mylist 7 mylis
197. ive a command to the patches or turtles using ask Like in the first example O 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 P gt set pcolor white you only have to give the command itself e Press setup What happened Why did the Graphic Window 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 changing 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 38 Tutorial 2 Commands NetLogo 3
198. k turtles fd random 10 ask turtles do calculation Here some of the turtles will have to wait after moving until all the other turtles are done moving Then the turtles all begin do calculation at the same time This latter form is equivalent to this use of the comma in StarLogoT fd random 10 do calculation 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 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 Programming Guide 87 NetLogo 3 0 User Manual The Primitives 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 contains numbers and strings this way as well as lists within lists forexample 2 4 3 511
199. kept even across multiple loads of the extension e system on Windows bundled Java version is now 1 4 2 08 was 1 4 2 05 Version 2 1 December 2004 e much larger and higher quality library of turtle shapes e runs models headless with no GUI from the command line e editor now highlights matching parentheses and brackets e action keys let buttons be triggered by keypresses e makes Quicktime movies of models e redesigned Command Center for greater usability e optional output area in models e greatly improved shapes editor e easy capture of images from Interface tab e multilevel Undo in editor e new let command for easy creation of local variables e new carefully command for trapping runtime errors e computer HubNet substantially improved reliability server discovery is now fully supported you may serve multiple activities simultaneously from the same computer improved client interface and Control Center Version 2 0 2 August 2004 e new experimental extensions API lets users write new commands and reporters in Java e NetLogo can now make sounds and music this is done with a new experimental sound extension that is also an example of how to use the extensions API e new controlling API lets users control NetLogo from external Java code such as for automating multiple runs 10 What s New NetLogo 3 0 User Manual Version 2 0 December 2003 e full support for Mac OS X improved Linux support e minimu
200. 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 simultaneously 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 Using the Sound Extension The sound extension comes pre installed To use the extension in your model add a line to the top of your procedures tab extensions sound jar For more information on NetLogo extensions see the Extensions Guide Please note that the NetLogo extensions facility is under development and is still considered experimental so the syntax is likely to change in a future version of NetLogo Models saved as applets using Save as Applet on NetLogo s File menu cannot make use of extensions We plan to fix this in a future release For examples that use the sound extension see the Sound section under Code Examples in the NetLogo Models Library Primitives drums instruments play drum play
201. l 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 no label 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 down ppd plot pen up ppu 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 222 Primitives Dictionary NetLogo 3 0 User Manual plotxy plotxy number number2 Moves the current plot pen to the point with coordinates number1 number2 If the pen is down 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 ra
202. 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 MIES 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 with 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 25 NetLogo 3 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
203. ll get an error message Command Center A Clear ERROR Expected a number here rather than a list or block patches gt ask patch O set pcolor blue Jr 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 coordinates e Type ask patch 11 4 set pcolor blue and press return What are the two words in this command that tip you off that we are addressing a patch 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 In Tutorial 3 Procedures you can learn how to alter and extend existing models and build your own models Tutorial 2 Commands 43 44 NetLogo 3 0 User Manual Tutorial 2 C
204. llustrate various advanced plotting techniques Also check out the following code examples Code Examples Plot Axis Example Plot Smoothing 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 Most of the list primitives work on strings as well butfirst string gt tring butlast string 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 To concatenate strings that is combine them into a single string you can also use the plus operator like this tur Ele gt turtle If you need to embed a special character in a string use the following escape s
205. 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 198 Primitives Dictionary NetLogo 3 0 User Manual 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 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 Authoring 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
206. luster of computers e Can use screen edge x or screen edge y etc as the minimum or maximum of a slider e Can change the choices in a chooser on the fly e Can divide the code for my model up into several files Programming e How is the NetLogo language different from the StarLogoT language How do convert my StarLogoT model to NetLogo e How does the NetLogo language differ from other Logos e The NetLogo world is a torus that is the edges of the screen are connected to each other so turtles and patches wrap around Can use a different world topology bounded infinite plane sphere etc 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 patch ahead 1 is reporting the same patch my turtle is already standing on Why e How do give my turtles vision e Does NetLogo have a command like StarLogo s grab command e tried to put at after the name of a variable for example variable at 1 0 but NetLogo won t let me Why not e I m getting numbers like 0 10000000004 and 0 799999999999 instead of 0 1 and 0 8 Why e How can use different patch neighborhoods circular Von Neumann Moore etc e Can connect turtles with lines to indicate connections between them e How can keep two turtles from occupying the same patch e How can find out if a turtle is dead e How do find out how much time has passed in my model e Does NetLogo
207. ly bugs 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 e On versions of Mac OS X prior to 10 4 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 The bug does not occur on OS X 10 4 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 e On Mac OS X 10 2 only the User Manual item on the Help menu will sometimes launch a web browser other than your default browser e On Mac OS X 10 2 only opening the Models Library can trigger an error if you have malformed fonts installed If this happens you should determine which fonts in System Library Fonts and other font directories are causing the problem and remove them Known Issues 17 NetLogo 3 0 User Manual 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 com
208. m Java version is now 1 4 1 Windows 95 MacOS 8 MacOS 9 no longer supported e increased overall reliability e improved look and feel throughout the application e faster and more flexible graphics labels turtle sizes exact turtle positions all now fast reliable and flicker free e suite of primitives for reading and writing external files e strict math mode now always on for reproducible results e export graphics window or interface tab as image file e revamped BehaviorSpace various improvements made some old features are missing e Mersenne Twister random number generator e many new primitives e computer HubNet improved reliability no longer alpha or beta improved graphics window mirroring features and performance Version 1 3 June 2003 e graphics window control strip e choosers e strict math mode so results are identical on all platforms requires Java 1 3 or higher e new primitives including run runresult and map foreach filter reduce e some primitives now accept a variable number of inputs Version 1 2 March 2003 e alpha release of computer HubNet formerly HubNet required the TI Navigator calculator network to operate now you can use it over TCP IP with networks of laptop or desktop computers e new primitives and other language improvements e display of coordinates when mousing over plots Version 1 1 July 2002 e Save as Applet lets you embed your model in any web page e printer support e Procedures
209. maining in the file Use the reporter filge at end to determine if you are at the end of the file file open myfile txt print file read line gt Hello World See also file open file show 190 Primitives Dictionary NetLogo 3 0 User Manual 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 Also all strings have their quotes included similar to_file write Note that this command is the file i o equivalent of show and 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 lts outpu
210. mand 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 more 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 Known issues with computer HubNet See the_HubNet Guide for a list of known issues with computer HubNet Unimplemented StarLogoT primitives The following StarLogoT primitives are not available in NetLogo Note that many StarLogoT primitives such as count turtles with are inten
211. mands let you track the movements of a particular agent new System Dynamics Modeler found on Tools menu includes sample models and section in User Manual new drawing layer on top of patches contains marks left by turtles with their pens or by stamping their shapes turtle pens may now vary in size they draw in the drawing layer rather than affecting patch colors as before buttons take turns now instead of interleaving their code with each other so you can press SETUP during GO or press GO during SETUP and the right thing happens 4 4 4 4 0 440 o o What s New 7 NetLogo 3 0 User Manual find and replace in Information and Procedures tabs new color palette is more muted and contains colors that harmonize better with each other the Information tab is now displayed in a more attractive but read only style use the new Edit button to switch to the old view for editing new GoGo extension allows interfacing NetLogo to physical devices added Color Swatches a dialog which helps you choose colors for your agents to the Tools menu improved user interface for reporting syntax errors no more Errors tab turtle shapes now optionally wrap around the edges of the world when you pick a turtle or patch with the mouse by right clicking or control clicking the selected turtle or patch is now highlighted substantial improvements to BehaviorSpace 0 BehaviorSpace experiments can now be run headless from the command line
212. menu instead User Manual Opens this manual in a web browser Main Window 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 Information Procedures TEN 7 Chooser BS Monitor Vi plot Ed Output 5 Text a E 7 Taoa Pt E abe Button am Slider 8 Switch 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 Center which allows you to issue NetLogo commands Interface Toolbar The toolbar contains buttons that let you edit delete and create items in the Interface tab such as buttons and sliders Interface Guide 63 NetLogo 3 0 User Manual Chooser ES Monitor Plot FE Output 5 Text f Edic BB Dele Zabe Button e Slider FSA switch mea The buttons in the toolbar are described below Working With Interface Elements Selecting To select an interface element drag a rectangle around it wi
213. mple extension manifest txt Extension Name exampl Class Manager SampleExtension etLogo Version 2 0 2 4 Create a JAR To create an extension JAR first compile your classes as usual Make sure Net Logo jar from the NetLogo distribution is in your classpath For example 132 Extensions Guide NetLogo 3 0 User Manual javac classpath NetLogo jar IntegerList java SampleExtension java Then create a JAR containing the resulting class files and the manifest For example jar cvfm example jar manifest txt IntegerList class SampleExtension class For information about manifest files JAR files and Java tools see java sun com 5 Use your extension in a model To use our example extension put the extension JAR 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 jar Now you can use first n integers just like it was a built in NetLogo reporter For example select the Interface tab and type in the Command Center O gt show first n integers 5 observer 1 2 3 4 5 Extension development tips Debugging extensions There are special NetLogo primitives to help you as you develop and debug your extension Like the extensions facility itself these are considered experimental and will be changed at a later date That s why they have underscores in their name eprint __dump extensions prints info
214. n 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 From the popup menu that appears choose inspect turtle 0 A turtle monitor for that car will appear 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 turtles have an ID number we call their 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 turtle 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 Tutorial 2 Commands 41 NetLogo 3 0 User Manual other way is to 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
215. n 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 CONTRIBUTORS BE LIABLE FOR ANY DIRECT INDIRECT INCIDENTAL SPECIAL EXEMPLARY OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO Copyright Information 3 NetLogo 3 0 User Manual 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 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 provid
216. n me A A A AE O 232 Moluscos lanas 232 OUN OA 232 Uli AA cumeata leaned a AD ido 233 UNI o Seara ane 3 ee e o dond eo Bie acts 224k 233 A RAR 233 CAOS A A tas 233 screen edge x SOTBON eOQO Yeccocococococcoocnnn ono nono nnnnnnnnnnnn nono nnnnnnnnn nn nn nn nn nn nn nro n nn nn nnnonnnnnnos 234 screen size x A eee eeeeeeeeceeeceeececeeeeeeeeeeeeeeeeeaeeeaeeeeeaeeeseaeaeenseeseeeneeesseene 234 A A e ia tl A T 234 SEMICON nee a N a a it 235 EAEI AEE der I ANE E EE E E E E T A 235 SOL E TEE RENEE O EA E EA E E A E E SEC 235 xii NetLogo 3 0 User Manual Table of Contents Primitives Dictionary Set Current CIreClOry viii hii cessar sta aE E N Ea A a nana das a eesti dels 236 SEL CUMMENTEDIOL sekire ia AR Edda a daran 236 Set CUIrentplO 01 1 ee 236 sot de taula a de a in 236 set niStograM nNUM DAS riada acta 237 set plol pen COlOL iii ii ai Ear 237 eee e o a el Cle ee 237 SEt PlOt PEN MOS oi sovaysdesydeassaaseawsev ses say a E a a e En 237 set plot x range Set plOl Y ANQl oococococonoccconnooononnno nono iss nono nono nono nnnnnnnnnnnonnnonnnnnnos 238 A O antes 238 SHAD SSO ta ra EA E A da RO e NA er E 238 Ai dd 239 SHADES AAA aid nae ea 239 SOW rs Mette di leita cee Ne th ae Labi Di a o aa R S a la ala fa el ia saeelatis amp Dt da ete eh cade 239 SHOWIUMIEG Sh esticar a hit eet a dE cd 239 SHUTS are tices tata tio a ds A Glee tt 240 CTA PRO E AE RENDA av tds tea eed hia O ANN O DR RAND Seda Sadun Oho ved RA
217. n of JOGL on your computer If for some reason NetLogo is unable to find and use the correct version it will warn you If you get such a warning you may need to remove your separate JOGL installation in order for NetLogo s 3D View to work On a Linux machine if NetLogo is finding the wrong version of JOGL trying running with the Djava ext dirs command line option like this java Djava ext dirs jar NetLogo jar That should fix the problem If it doesn t try removing your JOGL installation Removing an old JOGL If NetLogo tells you you need to remove your JOGL installation here s how to do it You need to remove the jogl jar file and one or two native library files e Remove jogl jar from 1ib ext in your Java home directory e On Mac OS X remove liblog1 3nilib from Library Java Extensions or Library Java Extensions e On Windows remove 3og1 d11 and jog1_cg d11 from jre bin in your Java home e On Linux remove 1ibjog1 so from your always checked Java native libraries directory System Requirements 15 16 NetLogo 3 0 User Manual System Requirements Known Issues If NetLogo malfunctions please send us a bug report See the Contact Us section for instructions Known bugs all systems e Integers in NetLogo must lie in the range 2147483648 to 2147483647 if you exceed this range instead of a runtime error occurring you get incorrect results e Out of memory conditions are not handled gracefull
218. n on NetLogo extensions see the Extensions Guide Please note that the NetLogo extensions facility is under development and is still considered experimental so the syntax is likely to change in a future version of NetLogo Models saved as applets using Save as Applet on NetLogo s File menu cannot make use of extensions We plan to fix this in a future release 140 NetLogo GoGo Extension NetLogo 3 0 User Manual For examples that use the GoGo extension see the GoGo section under Code Examples in NetLogo s Models Library Primitives gogo open gogo open gogo open gogo ports output port coast output port off output port reverse output port thailthis way ping sensor set output port power talk to output ports gogo close gogo close Close the connection to the GoGo Board See also gogo open and gogo open gogo open 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 poris 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 th
219. nce to create the turtles press the go button Watch what happens Turn it off and you ll see that all turtles stop in their tracks We suggest you start experimenting with other turtle commands You might try typing turtles gt pendown into the Command Center and then pressing go Another thing to try is changing set heading random 360 to rt random 360 inside of move turtles rt is short for right turn Also you can try changing set heading random 360 to It random 45 inside of move turtles Type commands into the Command Center like set colorred or add them to setup go or move turtles Note that when you enter commands in the Command Center you must choose turtles gt patches gt or observers in the popup menu on the left depending on which agents are going to execute the commands You can also use the tab key which you might find more convenient than using the popup menu turtles gt commands is identical to observer gt ask turtles commands and patches gt commands is identical to O gt ask patches commands Play around It s easy and the results are immediate and visible one of NetLogo s many strengths Regardless the tutorial project continues 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 Go back to the setup procedur
220. nd Be careful of the spacing around the In Tutorial 2 we used red 2 with spaces in order to subtract two numbers but here we want move turt les without spaces The combines move and turtles into one word Line by line ask turtles commands says that each turtle should execute the commands in the brackets set heading random 360 is another command that uses a reporter First each turtle picks a random integer between 0 and 359 random doesn t include the number you give it as a possible result Then the turtle sets its heading to the number it picked Heading is measured in degrees clockwise around the circle starting with 0 degrees at twelve o clock north fd 1 Each turtle moves forward one step in the new direction it just set its heading to 48 Tutorial 3 Procedures NetLogo 3 0 User Manual Why couldn t we have just written that in go We could 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 could include many other things you want to have happen as the model runs such as calculating something or plotting the results Each of these sub procedures could have its own name The go button you made in the Interface tab is a forever button meaning that it will continually execute its code until you shut it off by clicking on it again After you have pressed setup o
221. nd Screen Edge Y You can also right click Windows or control click Mac on the 2D view to edit it or select it then double click 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 your 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 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 512 megabyte ceiling on how much total RAM it c
222. nd half height of the NetLogo world the distances from the origin to the edges screen size is the same as 2 screen edge 1 Note You can set the size of the world only by editing the current view these are reporters which cannot be set cct 100 setxy random float screen edge x random float screen edge y 7 distributes 100 turtles randomly in the 5 first quadrant screen size x screen size y screen size x screen size y These reporters give the total width and height of the NetLogo world Screen size is the same as 2 screen edge 1 self self XE Reporis this turile or patch 234 Primitives Dictionary NetLogo 3 0 User Manual self and myself are very different self is simple it means me patch who asked me to do what I m doing right now myself means the turtle or ask turtles with self myself die this turtle kills all other turtles 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 valuen Makes a list out of the values If any value is a list its items are included in the result directly rather than bei
223. new commands and reporters in Java See Controlling and Extensions in the User Manual Do you offer any workshops or other training opportunities for NetLogo 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 What s the difference between StarLogo MacStarLogo StarLogoT 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
224. ng to setup Ca setup patches setup turtles end 7 Creates a random landscape of patch elevations to setup patches ask patches set elevation random 10000 repeat smoothness diffuse elevation 1 ask patches set pcolor scale color green elevation 1000 9000 set highest max values from patches elevation set lowest min values from patches elevation ask patches 58 Tutorial 3 Procedures NetLogo 3 0 User Manual if elevation gt highest 100 set pcolor white if elevation lt lowest 100 set pcolor black end initializes the turtles to setup turtles crt number ask turtles if shade of green color set color red fd random screen edge x end RUN TIME PROCEDURES 77 main program control to go set turtles moved false move to local max do plots if not turtles moved stop end 77 each turtle goes to the highest elevation in a radius of one to move to local max ask turtles set heading uphill elevation if elevation of patch ahead 1 gt elevation fd 1 set turtles moved tru end to do plots set current plot Turtles at Peaks plot count turtles with elevation gt highest 100 end Tutorial 3 Procedures 59 60 NetLogo 3 0 User Manual 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
225. ng included as a sublist Examples make this clearer how sentence 1 2 gt fd 2 how sentence 1 2 3 Se IPs 23 how sentence 1 2 3 gt 1 23 how sentence 1 2 3 4 gt 122 3 45 how sentence E 2y 7 1 3741 gt 1 21 13 41 how sentence 1 2 3 4 5 3 3 7 123456 7 bo lalalala i a Vv set set variable value Sets variable to the given value Variable can be any of the following e An global variable declared using globals e The global variable associated with a slider switch or chooser 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 Primitives Dictionary 235 NetLogo 3 0 User Manual e An expression of the form VARIABLE of agent e A local variable created by the let command 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 C 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
226. nge 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 rin string gt 2 See also_member precision precision number places Reports number rounded to places decimal places Primitives Dictionary 223 NetLogo 3 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 pycor El k These are built in patch 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 screen edge x and less than or equal to screen edge x similarly for pycor and screen edge y All patch variables can be d
227. nimum value of the variable patch variable of the patches in a one patch radius of the turtle This could be as many as eight or as few as five patches depending on the position of the turtle within its patch If there are multiple patches that have the same smallest value a random one of those patches will be selected If the patch is located directly to the north south east or west of the patch that the turtle is currently on a multiple of 90 degrees is reported However if the patch is located to the northeast northwest southeast or southwest of the patch that the turtle is currently on the direction the turtle would need to reach the nearest corner of that patch is reported See also_downhill4 uphill uphill4 downhill4 downhill4 patch variable Reports the turtle heading between 0 and 359 degrees as a multiple of 90 degrees in the direction of the minimum value of the variable patch variable of the four patches to the north south east and west of the turtle If there are multiple patches that have the same least value a random patch from those patches will be selected See also_downhill uphill uphill4 dx dy dx dy x 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 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 e
228. nnnnnnnnnnnninnniinnnss 169 MOVIG DTIMIIVES cunas nai as 169 System DAMIAN Na EA TN T 169 B tan Manables ui ls a 169 TUNES a ada A a Ae e a o il AN NA er 169 Pale a tea eS TAT Roda 169 AA A E RA 169 ROW Sii in 169 GOMSTAIIS e e EE T 170 vii NetLogo 3 0 User Manual Table of Contents Primitives Dictionary viii Mathematical Constants e ccceccccececceeccccececneeecaneecenueecaeneenseeeeaeeeaueeeaeesaenesaneseeaeeees 170 Boolean iGonstantS ssa este ceeds Coast ated heeds prs ceded even a eed eet dna A tee e 170 COlORGONMSTANIS ni e TA Ue UA A A 170 MUS JOIAS NE NR lace ted ovata tied taste in A tia 180 ITS OA aise of ss RRA 180 A AO 181 CAUSAN ed TT 181 CISTANCE NOWra Sii A A A A A 182 USAN Ci AA A tained 182 distancexy nowrap rre 182 NetLogo 3 0 User Manual Table of Contents Primitives Dictionary down A ev ens as ee E E 182 GOW AMINA PEE PA EE dr al fete dead ated TE as 183 CRC aaa EOE Pot tN aOR ME Ree E DD 183 Ese SAA A Sele NG a ninia Aske 183 EMP ais 184 ee A A O RE O 184 OITOIMOSSQOQNO coocccccccnccnnccnnccnnncnnncnnoconaconano nano EA EAEE nana rrenan arara area 184 OVO Vapon e ara AKE eKA Me sa nico del a ley deans eevee eben eines 184 O 185 export view export interface export output export plot export all plots EDA OLON EAL ONA O PEE AE dia 185 EXTIENDE 186 XT A Ginn She a ih Sani niin eran 186 1 E EE P E ROA 186 TAC STAGE AMOW RT 187 facexy facexy NOWra Dni 187 E
229. nnot be accessed or changed from this box To clear this box click clear in the top right corner To toggle between a vertical and horizontal split between the Command Center and the model interface click the button with the double headed arrow The smaller text box below the large box is where commands are entered On the left of this box is the agent popup menu and on the right is the history popup menu The agent popup menu allows you to select either observer turtles or patches This is an easy way to assign an agent to a command and it is the same as writing ask turtles Note a quicker way to change between observer turtles and patches is to use the tab key on your keyboard The history popup menu lists all of the commands entered that can be accessed and used again The up and down arrow keys on your keyboard will retrieve that last command that was written Note that pressing the clear function clears only the large display box and not the history To clear the history section choose clear history found at the top of its popup menu 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 Procedures tab Interface Guide 69 NetLogo 3 0 User Manual Interface Information Y crea globals ticks breeds sheep wolves turtles own
230. not have a separate output area then the Command Center is used P patch patch pxcor pycor Given two integers reports the single patch with the given pxcor and pycor The coordinates are the actual coordinates they are not computed relative to the calling agent as with patch at pxcor and pycor must be integers ask patch 3 4 set pcolor green 7 patch with pxcor of 3 and pycor of 4 turns green 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 set pcolor of patch ahead 1 green 7 turns the patch 1 in front of the calling turtle Er green note that this might be the same patch pari 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 Reports the single patch at dx dy from the caller that is dx patches east and dy patches north of the caller If the caller is the observer the given offsets are computed from the origin ask patch at 1 1 set pcolor green 7 if caller is the observer turn the patch ae at 1 1 green 7 if caller is a turtle or patch turns the 218 Primitives Dictionary NetLogo 3 0 User Manual 5 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 p
231. ns 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 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 138 Controlling Guide NetLogo 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 NetLogo GoGo Extension provides primitives to c
232. ns 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 Tutorial 1 Models 27 NetLogo 3 0 User Manual 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 0 and a maximum value of 250 The model could run with 0 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 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 is extremely helpful for gaining insight into the model Wit
233. nt shades in each row so when the increment is 0 1 there are 100 different shades in each row Note 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 A fixed set of discrete hues 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 for display color values are rounded to the nearest 0 1 so for example there s no visible difference between 26 5 and 26 52 There are a few primitives that are helpful for working with color shades The scale color primitive is useful for converting numeric data into colors And shade of will tell you if two colors are shades of the same basic hue For example snade of orange 27 is true because 27 is 80 Programming Gu
234. nt to create 50 turtles with the shape rabbit Provided there is some shape called rabbit in this model give this command to the observer in the command center O gt crt 50 And then give these commands to the turtles to spread them out then change their shape T gt fd random 15 T gt set shape rabbit Voila Rabbits Note the use of double quotes around the shape name Shape names are strings The set default shape command is also useful for assigning shapes to turtles 106 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 whic
235. nt turtles 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 count frogs Counti mace count birds 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 world command Measure runs at every tick Normally NetLogo will measure model runs at every tick 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 as well BehaviorSpace Guide 109 NetLogo 3 0 User Manual Go commands These commands will be run over and over again to advance to the model to the next tick 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 Final comman
236. nterface files in the HubNet Computer Activities section of the Models Library Disease nlogo and Disease client nlogo are good ones to start with View Updates on the Clients Currently there are two ways of sending the clients the View The first way is done automatically by NetLogo and HubNet when 2D View mirroring is enabled and the client has a View in the interface Whenever a patch or turtle is redrawn in the NetLogo View it will be redrawn on all the clients Actually updates are accumulated and sent out periodically about five times a second This means that a lot of messages can be sent to the clients if a lot of turtles or patches are being redrawn It is possible to reduce the number of messages sent to the clients and thus possibly speed up the model by making the View in the model not update This can be done using the no display and display primitives or by toggling the display on off switch in the View Control Strip A second way of sending the clients the View is to use the hubnet broadcast view and hubnet send view primitives hubnet broadcast view and hubnet send view both send the entire View to the clients instead of just the patches that need to be redrawn This makes them less efficient but for some models this is feature is necessary To send the View to the clients using this scheme you must use the following NetLogo code hubnet broadcast view to send to all the logged in clients To just send the View to a sub
237. nterpreted 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 68 Interface Guide NetLogo 3 0 User Manual 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 turtles patches and the observer This is useful for inspecting and manipulating agents on the fly Tutorial 2 Commands is an introduction to using commands in the Command Center Let s take a closer look at the design of the Command Center Command Center A 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 d You will notice there is a large display box an agent popup menu observer gt a clear button a button with the double headed arrow to relocate the command center to the right side of the window and the history popup menu in the lower right with the little black triangle The top large display box temporarily stores all of the commands that are entered into the Command Center This area is strictly for reference commands ca
238. ntly active You can also use Export Interface or the export interface command to save an image of the entire interface tab Can make a movie of my model Yes See the Movie section of the Programming Guide Also see Movie Example in the Code Examples section of the Models Library Does NetLogo take advantage of multiple processors Nat for a single model run no The NetLogo engine is single threaded and we expect it to remain so You can take advantage of multiple processors to do multiple model runs concurrently though in either of two ways e By having multiple copies of NetLogo open in separate Java virtual machines see this answer for instructions e By writing Java code that uses the Controlling API to do headless model runs from the command line This is currently the only possible way to do multiple concurrent model runs within a single Java virtual machine See the Controlling section of the User Manual In a future version of NetLogo we hope to improve the support for multiple processors as follows e Allow multiple models to be open simultaneously each running in a different thread and hence on a different processor e Modify the BehaviorSpace tool to optionally do multiple model runs in parallel in a configurable number of separate threads so the runs would be spread across available processors Can distribute NetLogo model runs across a cluster of computers Many of the same comments in the previous
239. nts 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 you 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 110 BehaviorSpace Guide NetLogo 3 0 User Manual 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 tick 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 upd
240. nts or if the Mirror Plots on Clients checkbox in the HubNet Control Center is not checked then no plot updates are sent to the clients Clicking in the View on Clients If the View is included in the client it is possible for the client to send locations in the View to NetLogo by clicking in the client s View The tag reported by hubnet message tag for client clicks is the same as what is needed to send the View to a client the string View hubnet message reports a two item list with the x coordinate being the first item and the y coordinate being the second item So 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 round item 0 hubnet message and round item 1 hubnet message Text Area for Input and Display A few models use an experimental interface element in the HubNet client that allows the modeler to display text on the client that can change throughout the run of the activity Further it can allow users to send text back to the server If you are interested in using it in an activity please_contact us for further information HubNet Authoring Guide 127 NetLogo 3 0 User Manual 128 HubNet Authoring Guide 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
241. o 3 0 User Manual Unlike distance nowrap turtles and patches use the wrapped distance around the edges of the screen if that distance is shorter than the on screen distance distance nowrap distance nowrap agent k 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 Unlike distance this always reports the on screen distance never a distance that would require wrapping around the edges of the screen distancexy distancexy xcor ycor E Reports the distance from this agent to the point xcor ycor The distance from a patch is measured from the center of the patch Unlike distancexy nowrap the wrapped distance around the edges of the screen is used if that distance is shorter than the on screen distance if distancexy 0 0 gt 10 set color green 7 all turtles more than 10 units from 7 the center of the screen turn green distancexy nowrap distancexy nowrap 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 Unlike distancexy this always reports the on screen distance never a distance that would require wrapping around the edges of the screen downhill downhill patch variable 182 Primitives Dictionary NetLogo 3 0 User Manual Reports the turtle heading between 0 and 359 degrees in the direction of the mi
242. o 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 reading 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 98 Programming Guide NetLogo 3 0 User Manual The reading primitives include file read file read line file read characters and file at end Note
243. oad 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 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 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 FAQ Frequently Asked Questions 155 NetLogo 3 0 User Manual Usage Can run NetLogo from a CD Yes NetLogo runs fine on a read only file system How do change how many patches there are A quick method is to use the three sets of black arrows in the upper left corner of the 2D view Another method is as follows Select the 2D view by dragging a rectangle around it with the mouse Click the Edit button in the Toolbar A dialog will appear in which you may enter new values for Screen Edge X a
244. obLab Genetics Random Basic Advanced new system dynamics models Exponential Growth Logistic Growth Wolf Sheep Predation System Dynamics Wolf Sheep Predation docked new biology models Autumn Algae Moths Disease Solo Echo new physics amp chemistry models GasLab Circular Particles DLA Alternate DLA Alternate Linear Polymer Dynamics new cellular automaton model Life Turtle Based new computer science models Vants Merge Sort new math model Color Fractions new art models Sound Machines Optical Illusions new games Minesweeper Lunar Lander new code examples Neighbors Nowrap Example Halo Example Perspective Example 3D Shapes Example GoGoMonitor new perspective demos section with alternate versions of Ants Termites Flocking GasLab to demo new perspective features improved sample models Rugby bugfix GasLab Gas in a Box bugfix Vector Fields bugfix Virus bugfix Turtles Circling new look and controls Pursuit new look Rebellion new look Reactor X Section new look Sand better colors Virus better colors Shuffle Board Traffic Basic and most ProbLab models revamped code examples Shape Animation Example new look Random Seed Example now demonstrates new seed Image Import Example now demonstrates import pcolors and import drawing e features you can now view any model in 3D note though that the world remains 2D for 3D worlds use NetLogo 3D Preview 1 new follow ride and watch com
245. odel 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 26 Tutorial 1 Models NetLogo 3 0 User Manual 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 a Grass settings i Sheep settings Wolf settings Let s experiment with their effect on the behavior of the model 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 sheep 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 butto
246. of items show min values from turtles xcor 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 returns one random agent that meets the condition If you want all such agents use with 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 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 number1 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 0 See also_remainder mod and remainder behave the same for positive numbers but differently for 210 Primitives Dictionary NetLogo 3 0 User Manual negative numbers modes modes list Reports a list of the most common item or items in ist The input list may contain any NetLogo values If the input is an empty list 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 values from turtles pxcor 7 shows which columns of patches have the most turtles on them mouse down mouse down
247. off turtles are drawn as solid squares it takes less work for NetLogo to draw squares than special shapes so the model runs faster The freeze button freezes the view 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 unfreeze the view by turning the switch back on Most models run much faster when the view is frozen The size of the view is determined by three separate settings Screen Edge X Screen Edge 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 e Experiment with the three sets of black arrows on the left of the control strip What happens the first time you press one of them What happens after that Try all three sets of arrows The arrows give you a convenient way of changing the number of patches in the world NetLogo can t change the number of patches without starting the model over from the beginning so that s why it warns you the first time you press an arrow There are more world and view settings than there s room for in the control strip The Edit button lets you get to the rest of the settings 30 Tutorial 1 Models NetLogo 3 0 User Manual e Press the Edit button in the control strip A dialog box will open containing all the settings for the view e AOAO Screen edge X 25 of patches horizontally is twice this number plus one
248. oking at some of the sample models and code examples in the Models Library may help as well NetLogo 1 3 1 includes a StarLogoT model converter you just open the model from the File menu and NetLogo will attempt to convert it The converter doesn t do all that great a job though so the result will very likely require additional changes before it will work Note also that the model converter is no longer included in current versions of NetLogo so if you have models you want to use it on you will have to use NetLogo 1 3 1 to do the converting then open the model in a current version 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 160 FAQ Frequently Asked
249. old variable pen down new follow watch ride and follow me watch me ride me commands and subject reporter for focusing on individual agents new reset perspective command returns the observer to the default position and perspective the clear graphics command no longer exists in old models it is automatically replaced with cp ct all other commands with graphics in the name now use view instead e g export view new netlogo version reporter What s New NetLogo 3 0 User Manual new import pcolors and import drawing commands read image files in a variety of formats into the patch colors or drawing layer new in cone reporter lets you give a turtle a cone of vision new new seed reporter is useful for generating numbers to use as random seeds 4 new mouse inside reporter tells you whether the mouse pointer is in the view renamed get and date time to date and time the constant white is now defined as 9 9 not 9 9999 e engine fixes 4 fixed bug in random n of that favored earlier items in the list or agentset fixed bug where filter map foreach didn t always work properly inside run runresult fixed bug in importing worlds where an agentset stored in a global variable could be imported incorrectly if the import caused the world size to change the export view and export output Commands now work even when running headless from the command line when running headless from the command line paths are now
250. ommands Tutorial 3 Procedures In Tutorial 2 you learned how to use command centers 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 This tutorial leads you through the process of building a complete model built up stage by stage with every step explained along the way You ve already been exposed to the three types of agents you can give commands to in NetLogo turtles patches and the observer As you start to write your own procedures it ll be helpful to keep in mind how people usually think of these three different kinds of agents The turtles and patches usually don t use information about the whole world They mostly use information about what s close to them The observer on the other hand typically uses and accesses the whole world Also while patches can t move and often represent some sort of environment turtles can move around in the world Setup and Go To start a new model select New from the the File menu Then begin making your model by creating a once button called setup Here s how to make the button 1 Click on the button icon in the Toolbar 2 Click where you want the button to be in the empty white area of the Interface tab 3 When the dialog box for editing the properties of the button opens type setup in the box labeled Code e06 Button Agent s Observer C Forever Commands setup
251. ommunicate 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 ports 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 website 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 wi
252. on 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 specifics about writing procedures refer to the NetLogo Programming Guide Also You can continue with this model if you d like experimenting with different variables and algorithms to see what works the best what makes the most turtles reach the peaks 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 pleasant just to watch patches and turtles forming patterns or whatever Hopefully you will have learned a few things both in terms of syntax and general methodology for model building The entire code that was created above is shown below Appendix Complete Code The complete model is also available in NetLogo s Models Library in the Code Examples section It s called Tutorial 3 patches own elevation 7 elevation of the patch globals highest 7 maximum patch elevation lowest 7 Minimum patch elevation turtles moved so we know when to stop the model 7 We also have two slider variables number and 7 smoothness number determines the number of turtles and smoothness determines how erratic terrain becomes during diffusion of elevation 7 resets everythi
253. on 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 activity 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 Hub
254. once or twice 7 each turtle goes to the highest elevation in a radius of one to move to local max ask turtles set heading uphill elevation if elevation of patch ahead 1 gt elevation fd 1 end Now that you ve seen the uphill algorithm work in the model let s go through the new primitives involved If you haven t run the model yet since writing move to local max give it a try There are three new primitives here uphill of and patch ahead uphill elevation finds the heading to the patch with the highest value of elevation in the patches in a one patch radius of the turtle Then through the use of the command set heading the turtle sets its heading to that direction elevation of patch ahead 1 has each turtle look at the variable elevation in the patch on which the turtle would be if it went forward 1 If the test reports true the turtle moves itself forward 1 The test is necessary because if the turtle is already on the peak we don t want it to move off it Go ahead and type that in but before you test it out by pressing the go button ask yourself this question what do you think will happen Try and predict how a turtle will move where it will go and how long it ll take to get there When you re all set press the button and see for yourself Surprised Try to understand why the turtles converge to their peaks so quickly Maybe you don t believe the algorithm we ve chosen works cor
255. ontain the user name of the client that just logged on or off Also if hubnet message and hubnet message tag are used while hubnet enter message Or hubnet exit message are true a Runtime Error will be given Generally part of your go procedure will include checking for waiting messages and handling them to listen clients while hubnet message waiting 122 HubNet Authoring Guide NetLogo 3 0 User Manual hubnet fetch messag ifelse hubnet enter message create new student ifelse hubnet exit message remove student execute command hubnet message tag end Sending data It is also possible to send data from NetLogo to the clients For Calculator HubNet NetLogo sends the data to the Navigator server and then the calculators can then access it For Computer HubNet NetLogo is able to send the data directly to the clients The primitives for sending data to the server are 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 all the clients 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 hubnet send list of strings tag name value hubnet send string tag name value When using Calculator HubNet this primitive acts in e
256. operating systems Now that we know more about Agent Monitors we have three ways to change an individual turtle s color 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 turtles 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 42 Tutorial 2 Commands NetLogo 3 0 User Manual If you try to have the observer ask patch 0 set pcolor blue you
257. or plabel plabel color Example ask turtles set label who all the turtles now are labeled with their 7 id numbers ask turtles set label no label all turtles now are not labeled label color label color This is a built in turtle variable It holds a number greater than or equal to O and less than 140 This number determines what color the turtle s label appears in if it has a label You can set this variable to change the color of a turtle s label Primitives Dictionary 205 NetLogo 3 0 User Manual See also no label label plabel plabel color Example ask turtles set label color red 7 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 character string containing only the last character of the original string 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 random one of sheep her 1f prey nobody ask prey die 206 Primitives Dictionary NetLogo 3
258. orld Load a file that was saved by Export World Import Patch Colors Load an image into the patches see the impori pcolors ommand Import Drawing Load an image into the drawing see the import drawing ommand Quit Exits NetLogo On Macs this item is on the NetLogo menu instead Cut Cuts out or removes the selected text and temporarily saves it o the clipboard P u Copy Copies the selected text aste Places the clipboard text where cursor is currently located Delete _ Deletes selected text o Undo Undo last text editing action you performed Redo Redo last undo action you performed Select All Select all the text in the active window Find Finds a word or sequence of characters within the Information or Procedures tabs used Find with Shift Right ode Comment Used in the Procedures tab to add or remove semicolons from Uncomment ode semicolons are used in NetLogo code to indicate Halt Stops all running code including buttons and the command enter Warning since the code is interrupted in the middle of hatever it was doing you may get unexpected results if you ry to continue running the model without first pressing setup o start the model run over Globals Monitor Turtle Monitor Displays the values of all of the variables in a particular turtle ou can can also edit the values of the turtle s variables and issue commands to the turtle You can also open a turtle monito
259. ormation you want to send to the NetLogo model Further how those numbers are interpreted by the model is also up to you For more information on writing the calculator program portion of a HubNet Activity please_contact us Saving The data sent by calculators or NetLogo is saved in the order that the server receives the data 124 HubNet Authoring Guide NetLogo 3 0 User Manual Computer HubNet Information The following information is specific to Computer HubNet How To Make an Interface for a Client Open a new model in NetLogo Add any interface buttons sliders switches monitors plots choosers or text boxes that you want in the Interface Tab For buttons and monitors you only need to type a Display Name Any code you write in the Code or Reporter sections will be ignored The Display Name you give to the interface element is the tag that is returned by the hubnet message tag reporter in the NetLogo code For example if in the Interface Tab of the client interface you had 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 elemen tag t Move Left Move Left p size step size in one step ste all in one ste all in one step Location Location Be aware that this causes the restriction that you can only have one interface element with a specific name Having more
260. ose coordinates 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 ID 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 and ask them to do something This involves a concept called agentsets The next section explains this concept in detail Agentsets An agentset is exactly what its name implies a set of agents An agentset can contain either turtles or patches but not both at once You ve seen the turtles primitive which reports the agentset of all turtles and the patches primitive which reports the agentset of all patches But what s powerful about the agentset concept is that you can construct agentsets that contain only some turtles or some patches For example all the red turtles or the patches with pxcor evenly divisible by five or the turtles in the first quadrant that are on a green patch 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
261. plementations At the same time we will also provide real mutable arrays as a separate data type Does NetLogo have associative arrays or lookup tables No but you can use lists to accomplish the same thing though less efficiently See e http groups yahoo com group netlogo users message 2344 e http groups yahoo com group netlogo users message 2346 e http groups yahoo com group netlogo users message 2354 How can use different patch neighborhoods circular Von Neumann Moore etc The in radius primitives lets you access circular neighborhoods of any radius 164 FAQ Frequently Asked Questions NetLogo 3 0 User Manual The neighbors primitive gives you a Moore neighborhood of radius 1 and the neighbors4 primitive gives you a Von Neumann neighborhood of radius 1 If you want a Moore or Von Neumann neighborhood of a different radius or a different kind of neighborhood altogether you can define it yourself using the at points primitive and or other techniques If the neighborhoods do not change over time then the most efficient way to use them is to compute the neighborhoods only once ahead of time and store them in agentsets See this URL for a discussion and example code http groups yahoo com group netlogo users message 377 Can connect turtles with lines to indicate connections between them Yes See Network Example in the Code Examples section of the Models Library We plan to support this more d
262. 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 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 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 Specifying a pen When you make a new plot it just has one pen 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
263. quence 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 92 Programming Guide NetLogo 3 0 User Manual You will always get the numbers 95 7 and 54 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 we change the random number generator For example NetLogo 2 0 has a different generator than NetLogo 1 3 did 2 0 s generator which is known as the Mersenne Twister is faster and generates numbers that are statistically more random than 1 3 s Java s built in linear congruential generator 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 And it never reports the same number twice in 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 random one of and so on aren t the only ones that use pseudo random numbers Some other primitives also make random choic
264. r e 0 is pure black 9 9 is pure white e 10 20 and so on are all so dark they appear black 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 Programming Guide 79 NetLogo 3 0 User Manual You can also view a similar chart and experiment with the colors by opening the Color Swatches from the Tools Menu 606 Color Swatches gray 5 6 7 a 9 9 9999 red 15 19 9999 orange 25 brown 35 yellow 45 green 55 ime 65 Cet 62 66 j 67 68 68 699999 turquoise 75 cyan 85 as as 9999 amp 2 282 8 amp E amp amp Pood 0 z e E 99 99 9999 sky 95 blue 105 108 109 109 9999 violet 115 118 119 119 9999 magenta 125 128 129 129 9999 pink 135 RE od Copy selected color black M Numbers o 10 0 50 0 1 Increment When you click on any one of the color swatches or the color buttons that color will be displayed against all of the other standard colors along the right edge of the dialog and black and white along the top In the bottom left corner the value of the currently selected color is displayed so you can copy the color and easily insert it into your code In the bottom right corner 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 differe
265. r 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 open file open string This command will interpret string 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 188 Primitives Dictionary NetLogo 3 0 User Manual 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 exist when opening a file in reading mode When opening a file in writing mode all new data will be appended to the end of the original
266. r 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 242 Primitives Dictionary NetLogo 3 0 User Manual 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 turtle 1 4 gt urt 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 180 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
267. r of random one of turtles here yellow 7 on every patch a random turtle turns yellow Local variables 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 1et 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 78 Programming Guide NetLogo 3 0 User Manual those brackets to swap colors turtlel turtle2 let temp color of turtlel set color of turtlel color of turtle2 set color of turtle2 temp end NetLogo represents colors 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 19 199 orange 25 28 29 29 9 brown 35 a5 39 399 yellow 45 48 49 49 9 green 55 58 59 59 9 lime 65 68 69 69 9 turquoise 75 78 79 79 9 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 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 colo
268. r via the View see the View section below Patch Monitor Displays the values of all of the variables in a particular patch ou 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 Hide Show Command Makes the command center visible or invisible Note that the ommand center can also be shown or hidden or resized with 3D View Opens the 3D view See the View section for more information Color Swatches O 2 Interface Guide NetLogo 3 0 User Manual Opens the Color Swatches See the_Color Section of the Programming Guide for details A Pe turtle shapes See the_Shapes Editor Guide for more information BehaviorSpace Guide for more information System Dynamics Opens the System Dynamics Modeler See the System Modeler Dynamics Modeler Guide for more details HubNet Control Center Disabled if no HubNet activity is open See the HubNet Guide or more information Larger Increase the overall screen size of the model Useful on large monitors or when using a projector in front of a group Normal Size Smaller Decrease the overall screen size of the model his menu offers keyboard shortcuts for each of the tabs On Macs it s Command 1 through Command 4 On Window it s Control 1 through Control 4 About NetLogo Information on the current NetLogo version the user is running On Macs this menu item is on the NetLogo
269. re working on a compiler Long answer NetLogo does include a compiler but the compiler does not produce native code or even Java byte code It produces a custom intermediate representation that can be interpreted more efficiently than the original code However we are working on a new compiler that will generate Java byte code Once that is done NetLogo will qualify as compiled not interpreted Since Java virtual machines have just in time compilers that in turn compile Java byte code all the way to native code the new compiler should substantially improve the speed of NetLogo We are not sure when the new compiler will be done 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 1 may require some small changes in order to run in the FAQ Frequently Asked Questions 153 NetLogo 3 0 User Manual 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 bugsccl 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 presen
270. reates 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 212 Primitives Dictionary NetLogo 3 0 User Manual movie status movie status Reports a string describing the current movie print movie status gt No movie movie start print movie status gt 0 frames Framerate 15 0 movie grab view print movie status 1 frames Framerate 15 0 Size 315x315 myself myself st a 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 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 values from value from turtles from patches from histogram from 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 values n values size reporter Reports a list of length size containing values comp
271. rectly There s a simple procedure you can make to test it write a procedure recolor patches so that it says to recolor patches ask patches set elevation pycor set pcolor scale color green elevation 0 screen edge y screen edge y end Press setup The model looks the same as it did before because recolor patches hasn t been run yet Instead of making a button that calls your testing procedure let s do something different Type observer gt recolor patches into the command center the procedure gets called Now when you press go see that the turtles all head for the highest elevation the top of the screen Tutorial 43 Procedures 53 NetLogo 3 0 User Manual Another common tool to see what s going on is to write turtles gt pd in the Command Center Then each turtle traces its path with its color This will show you where the turtle has been Our turtles rapidly arrive at local maxima in our landscape Local maxima and minima abound in a randomly generated landscape like this one Our goal is to still get the turtles to find an optimal maximum which is one of the white patches Part of the problem is that our terrain is terribly lumpy Every patch picked a random elevation and then we diffused these values one time This really doesn t give us a continuous spread of elevation across the view as you might have noticed We can correct this problem to an arbitrary degree by diffusing more times Replace the line
272. ree different serial ports In that case try to open each of them until the connection is successful NetLogo GoGo Extension 141 NetLogo 3 0 User Manual output port coast output port coast Turns off the power of the active ports When attached to motors does not apply a braking force as output port off does Therefore the motor will gradually slow down before stopping completely This will have the same effect as output port off on most output devices other than motors The output ports effected by this command are determined by the talk to output ports command The following code will will turn on output port a for 1 second and then stop the motor gradually talk to output ports a output port on wait 1 output port coast output port off 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 talk to output ports command output port reverse output port reverse Reverses the direction of the output ports The output ports effected by this command are determined by the talk to output ports command output port that this way output port thatway 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 talk to output ports command Note that this is diff
273. ring 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 and the contents of the output area if one exists to an external file given by the string filename The result file can be read back into NetLogo with the impori world primitive export plot export all plots and export world save files in in plain text comma separated Primitives Dictionary 185 NetLogo 3 0 User Manual 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 that the functionality of these primitives is also available directly from NetLogo s File menu export world fire csv 7 exports the stat
274. rmation about loaded extensions eprint _ dump extension prims prints information about loaded extension primitives 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 extensions directory of the NetLogo installation Whenever an extension is imported NetLogo makes all the JARs in this folder available to the extension If you plan to distribute your extension to other NetLogo users make sure to provide installation instructions that describe which files should be copied to their extensions directory 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 Extensions Guide 133 NetLogo 3 0 User Manual The extensions facility is considered experimental This initial API doesn t include everything you might expect 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
275. rns 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 screen updates You might want to change lots of things on the screen 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 independently of the switch in the view control strip that freezes the view See also display no label no label This is a special value used to remove labels from turtles and patches When you set a turtle s label to no label or a patch s plabel to no label then a label will no longer be drawn on top of the turtle or patch See also label label color plabel plabel color nobody nobody This is a special value which some primitives such as turtle random 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 You only get nobody back in situations where you were expecting a single agent not a whole agentset set other random one of other turtles her i
276. rns right at points agentset at points x1 y1 x2 y2 Reports a subset of the given agentset that includes 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 fa 1 7 only the turtles on the patches at the distances 2 4 1 2 and 10 15 relative to the caller mov 172 Primitives Dictionary NetLogo 3 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 0 show atan 1 1 gt 315 0 autoplot autoplot Reports true if auto plotting
277. rst any previous points drawn by the current plot pen are removed The reporter should report a numeric value Any non numeric values reported 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 to 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 As of NetLogo 2 0 2 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 from turtles color 5 draws a histogram showing how many turtles there are of each color Note using this primitive amounts to the same thing as writing histogram list values from agentset reporter but is more efficient histogram list histogram list list Histograms the values in the given list after first removing any previous points drawn by the current plot pen See histogram from above for more information home home k The calling turtles moves to the origin 0 0 Equivalent to setxy 0 0 hsb hsb hue saturation brightness Reports a number in the range 0 to 140 not including 140 itself that represents the given color specified
278. rtle agentset reports the turtle in the set with the lowest numbered ID If given a patch agentset reports the patch in the set with the highest pycor and if a tie breaker is needed with the lowest pxcor If the agentset is empty reports_nobody See also random one of or boolean1 or boolean2 Reports true if either boolean1 or boolean2 or both is true Note that if condition is true then condition 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 turtles here other BREED here other turtles here other BREED here Reports an agentset consisting of all turtles on the calling turtle s patch not including the caller itself If a breed is specified only turtles with the given breed are included 7 suppose I am one of 10 turtles on the same patch show count other turtles her gt 9 Example using breeds breeds cats dogs show count other dogs here 7 prints the number of dogs that are not me on my patch See also_turtles here output print output show output type output write Primitives Dictionary 217 NetLogo 3 0 User Manual 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
279. rtles with lines to indicate connections between them 164 How can convert an agentset to a list or vice versa ii rreemaea 165 What if want to ask an agentset in random order eee 165 How does NetLogo decide when to switch from agent to agent when running code 165 FAQ Frequently Asked Questions is ssciieeessseseseeneenenasasessseneennnnananssacananaa 165 AAA cect ecexescvccetncccucsscecsorscasteevssusvccencesseerereete 167 Categories of PrimiliVeS 2 j ancsitosccnadiiuetedesvtieiansthwennnbyeteascapw s 167 Wurtle related sur asiss ias a a hare ta cosa dad Sea dani a ras bra e a atid 167 Patch related primitives te ara rara aaa a ana aerea ana aanaaanaaananananana 167 Agentsel PrIMILIVEOS cnc sieved Sra SENTA a area Dea dada arcada 167 Color PARMA E OS ARGS 168 Control flow and logic prMIVOS visa A its 168 World primitives ereta creer 168 Perspective primitives rare aerea ara aara rara nana nana ana aanaa nana ERK 168 HubNet prime iii daa dae ad ita a 168 Input output primitives rea tees rre 168 EIG prIMILIVES ad A a AEE 168 List DrIMIIVES oo aaa dades 168 Sting priMitV S rad tada 169 Mathematical priMitiVES oocccccccccccnccnncnnncnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnness 169 Plotting PriMitiVES ccocccccccnncnnncnnnnnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
280. s 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 and the addition operator also functions as a string concatenation operator see example below Primitives Dictionary 171 NetLogo 3 0 User Manual If you are not sure how NetLogo will interpret your code you should insert parentheses show 5 6 6 3 gt 32 show 5 6 6 3 gt 20 show tur tle gt turtle asin asin number Reports the arc sine inverse sine of the given number The input must be in the range 1 0 to 1 0 The result is in degrees and lies in the range 90 0 to 90 0 ask ask agentset commands ask agent commands Takes a list of commands that will be run by the specified agent or agentset 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 tu
281. s own fur cage dogs own hair puppies See also globals patches own breeds lt BREED gt own type type value Prints value in the Command Center not followed by a carriage return unlike_print and 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_show type 3 type print 4 gt 3 4 See also_print show and_write See also output type U uphill uphill patch variable x Reports the turtle heading between 0 and 359 degrees in the direction of the maximum value of the variable patch variable of the patches in a one patch radius of the turtle This could be as many as eight or as few as five patches depending on the position of the turtle within its patch If there are multiple patches that have the same greatest value a random one of those patches will be selected 248 Primitives Dictionary NetLogo 3 0 User Manual If the patch is located directly to the north south east or west of the patch that the turtle is currently on a multiple of 90 degrees is reported However if the patch is located to the northeast northwest southeast or southwest of the patch that the turtle is currently on the direction the turtle would need to reach the nearest corner of that patch is reported See also_uphill4 downhill downhill4 uphill4 uphill4 patch variable x Reports the turtle heading between
282. s 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 Xmx512M 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 spreadhseet lt filename gt argument specified that spreadsheet 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 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 Xmx512M cp NetLogo jar
283. s 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 4 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 in cone in cone nowrap agentset in cone distance angle agentset in cone nowrap distance angle This reporter lets you give a turtle a cone of vision in front of itself The cone is defined by the two 202 Primitives Dictionary NetLogo 3 0 User Manual inputs the vision distance radius and the view angle The view 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
284. ser 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 list2 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_2n 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 See also foreach 208 Primitives Dictionary NetLogo 3 0 User Manual max max list Reports the maximum number value in the list It ignores other types of items show max values from turtles xcor 7 prints the x coordinate of the turtle which is farthest right on the screen 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 comm
285. server 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 turtle If the turtle dies the view will return to the default position See also reset perspective watch follow subject ride me ride me k 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 232 Primitives Dictionary NetLogo 3 0 User Manual 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 in
286. ses 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 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 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 4 Copyright Information NetLogo 3 0 User Manual 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
287. set of all the clients use hubnet send view user name list where user name liist is either a single string or a list of strings of the user names of clients that you want to send it to 126 HubNet Authoring Guide NetLogo 3 0 User Manual If there is no View in the clients or if the Mirror 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 their behaviors 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 Plot Updates on the Clients When 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 If there is no plot with the exact same name in the clie
288. ships 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 exhibit BehaviorSpace can be a powerful assistant to the modeler BehaviorSpace Guide 107 NetLogo 3 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 se
289. son 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 Primitives Dictionary 225 NetLogo 3 0 User Manual lambda 1 variance mean 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 52 show random poisson 3 4 7 prints a Poisson distributed random integer with a mean of 3 4 random int or float random int or float number NOTE This primitive should not be used in new models It is included only for backwards compatibility with NetLogo 1 x It will not necessarily continue to be supported in future versions of NetLogo When
290. ss 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 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 118 HubNet Guide NetLogo 3 0 User Manual not always the entire IP address of the server e Authoring new HubNet activities is more arcane and difficult than it should be e Computer HubNet has only been tested on LANs and not on dial up connections or WANs Calculator HubNet Requirements To use
291. st 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 7 mylist is now 4 6 8 show but first string fi prints ering show but last string 7 prints strin C carefully carefully commands1 commands2 Runs commands1 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 Primitives Dictionary 175 NetLogo 3 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 w Resets all global variables to zero and calls clear turtles 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
292. st elevations are and where they can be found g setup go a highest lowest 0 0 An Uphill Algorithm Okay Finally we re ready to start hill climbing To rehash we ve got some turtles randomly spread out from the origin and we ve got a landscape of patches whose primary attribute is their elevation Lastly we have two kinds of tools to help us understand the patch landscape each patch has a color depending on its value of elevation and we have a pair of monitors telling us what the highest peak and lowest valley are What we need now is for the turtles to wander around each trying to get to the patch that has the highest elevation 52 Tutorial 43 Procedures NetLogo 3 0 User Manual Let s try a simple algorithm first We ll assume three things 1 that the turtles cannot see ahead farther than just one patch 2 that each turtle can move only one square each turn and 3 that turtles are blissfully ignorant of each other Before we had a procedure move turtles like this to move turtles ask turtles set heading random 360 fd 1 end But now we don t want them to move randomly about We want each turtle to look at the elevation of each patch directly around it and move to the patch with the highest elevation If none of the patches around it have a higher elevation than the patch it is on it ll stay put This new procedure should replace move turtles inside of go Type in the following code and run it
293. st keep the extension in the same folder as the model that uses it You can also use extensions that are not installed in your NetLogo extensions folder by providing a path relative to the directory that contains the model or an absolute path __ extensions lib sound jar 7 relative path _ extensions jars sound jar relative path extensions c myfiles sound jar absolute Windows path extensions Users me sound jar absolute Mac Unix path You may also use an extension which is stored on an Internet server instead of your local computer Extensions Guide 129 NetLogo 3 0 User Manual Just use the URL where you have stored the extension For example __extensions http yourdomain net jars sound jar 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 To use more than one extension list each extension seperately For example extensions sound jar speech jar Some extensions depend on additional files Check the instructions that come with the extension to see if you need to keep any other files with the extension Applets Models saved as applets using Save as Applet on NetLogo s File menu cannot make use of extensions We plan to fix this in a future release
294. 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 non existent client using hubnet send view generates a hubnet exit message Primitives Dictionary 199 NetLogo 3 0 User Manual 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 hubnet set client interface client type client info If client type is COMPUTER client info is a list containing a string with the file name and path relative to the model to the file which will serve as the client s interface This interface will be sent to any clients that log in hubnet set client interfac COMPUTER clients Disease client nlogo 7 when clients log in they will will get the 7 interface described in the file clients Disease client nlogo relative to 7 the location of the model 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 set color blue 7 t
295. sum values from 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 List sentence normally takes two inputs but can accept any number of inputs if the call is surrounded by parentheses Changing List Items Technically only one command changes a list set This is used in conjunction with reporters 88 Programming Guide NetLogo 3 0 User Manual For example to change the third item of a list to 10 you could use the following code set mylist 2 7 5 Bob 3 0 2 mylist is now 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 nest
296. t no If this is a problem for you contact us at feedback ccl northwestern edu I 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 future version but to troubleshoot it we need help from users 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
297. t is now 2 5 7 10 G globals globals var1 var2 This keyword like the breeds lt BREED gt own patches own and turiles 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 used in many parts of the program H hatch hatch lt BREED gt hatch number commands hatch lt BREED gt number commands This turtle creates number new turtles each identical to its parent and asks the new turtles to run commands You can use the commands to give the new turtles different colors headings or whatever If the hatch lt BREED 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 the new turtles cannot interact with any other agents until they are fully initialized In addition no screen updates take place until the commands are done This ensures that the new turtles are never drawn on screen in an only partly initialized state hatch 1 1t 45 fd 1 7 this turtle creates one new turtle 7 and the child turns and moves away hatch sheep 1
298. t will 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 Primitives Dictionary 191 NetLogo 3 0 User Manual 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 reporter use to refer to the current item of list 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 w Similar to ride but in the 3D view the view 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 192 Prim
299. tem 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 use of Xmx to specify a maximum heap size of 512 megabytes If you don t specify a maximum heap size you will get your VM s default size which may be unusably small 512 megabytes is an arbitrary size which should be more than large enough for most models you can specify a different limit if you want BehaviorSpace Guide 111 NetLogo 3 0 User Manual The model 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 it a name Here s another example that shows some additional optional arguments java Xmx512M cp NetLogo jar org nlogo headless HeadlessWorkspace model Fire nlogo xperiment experiment2 screen edge x 100 screen edge y 100 no results Note the use of the optional screen edge x and screen edge y 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 screen edge x and screen edge y if they are specified by the experiment 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 i
300. terprets 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 to the values of local variables myself and so on See also_runresult 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 See also_run S scale color scale color color number range1 range Reports a shade of color proportional to number Primitives Dictionary 233 NetLogo 3 0 User Manual If range 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 range1 then the darkest shade of color is chosen If 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 screen edge x screen edge y screen edge x screen edge y These reporters give the maximum x coordinate and maximum y coordinate respectively of the world screen edge x and y are the half width a
301. th edges checkbox controls the use of anti aliasing in the 3D view only It will make the lines appear less jagged but it will slow down the model Turtle and patch 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 66 Interface Guide NetLogo 3 0 User Manual the approriate item in the turtle submenu Turtle and patch 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 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 r
302. th 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 to 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 To communicate with the GoGo Board through the serial port the GoGo Extension uses Sun Microsystem s Java Communications API In each platform PC Mac Linux the procedures for installing the software needed to enable serial communication are slighly different Mac OS X There is no official implementation of the Java Communications API for OS X but the RXTX project provides an open source implementation You can download the RXTX installer for OS X from SourceForge Be sure to follow all the directions in the installer to create lock file directories and make sure your user is in the appropriate groups to use the lock files There are several commercial implementations of the Java Communications API for OS X which have not been tested with the GoGo extension but in theory should work Please contact us if you NetLogo GoGo Extension 139 NetLogo 3 0 User Manual succesfully use them or run into problems trying Windows Sun prov
303. th 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 Macintosh 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 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 t
304. 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 When you are finished using a file you can use the command ile close to end your session with the file If you wish to remove the file afterwards use the primitive ile delete to delete it To close multiple opened files one needs to first select the file by using file 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 ile 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
305. the same directory on the server where the model is stored set current directory C NetLogo j Assume it is a Windows Machine file open myfile txt 77 Opens file C NetLogo myfile txt set current plot set current plot plotname Sets the current plot to the plot with the 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 set default shape turtles string set default shape breed string gt 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 236 Primitives Dictionary NetLogo 3 0 User Manual The specified breed must be either turtles or a breed defined by the breeds 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 7 new turtle s shape is default set default shape turtles circle create turtles 1 new turtle s shape is circl
306. there are three types of agents turtles patches 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 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 Patches have coordinates The patch in the center of the world has coordinates 0 0 We call the patch s coordinates pxcor and pycor Just like in the standard mathematical coordinate plane pxcor increases as you move to the right and pycor increases as you move up Programming Guide 75 NetLogo 3 0 User Manual The total number of patches is determined by the settings screen edge x and screen edge y When NetLogo starts up both screen edge x and screen edge y are 17 This means that pxcor and pycor both range from 17 to 17 so there are 35 times 35 or 1225 patches total You can change the number of patches by editing NetLogo s view 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 b
307. 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 show sensor 1 7 will show the value of sensor 1 foreach 1234567 8 show word Sensor sensor 7 will show the value of all sensors in the Command Center if 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 forever if sensor 1 lt 500 ask turtles fd 10 7 will continuously check sensor 1 s value and 7 move all turtles 10 steps forward every time 7 that the sensor value is less than 500 NetLogo GoGo Extension 143 NetLogo 3 0 User Manual set output port power 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 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 talk to motors Tat Mb HEM gu set motor power 4 7 will lower the power of all output ports by half of the full power 144 NetLogo GoGo Extension NetLogo Sound Extension The NetLogo Sound Extension provides primitives to add sound to NetLogo models The extension simulates a 128 key electronic
308. thods on App import org nlogo headless HeadlessWorkspace import org nlogo compiler CompilerException 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 J System out println workspace report burned trees 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 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 136 Controlling Guide NetLogo 3 0 User Manual 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
309. tionally not included in this list because NetLogo allows for the same functionality with the new agentset syntax e maxint minint maxnum minnum e import turtles import patches import turtles and patches note that NetLogo adds import world though ebit bitand bitneg bitor bitset bitstring bitxor make bitarray rotate left rotate right shift left shift right e camera brightness camera click camera init camera set brightness enetlogo directory project directory project name project pathname save project 18 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 staff and our various research activities Feedback Questions Etc If you have general feedback suggestions or questions write to feedback ccl northwestern edu If you need help with your model you should also consider posting to the NetLogo users group at http groups yahoo com group netlogo users 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
310. tionary xiv O ee ease USCL CNOICOS crias ra donas pt a be a AE ad idade a RD e ea AT SS user choose directory re eereeaeaeaeaaaeaaaaaana nana cana nana rananananananana USEr ChOOSe Tile sas O aba aa user choose new file rara arena a arena a VAIS STOMA ds Avie PEE TE AAIE o sea ia cents E na ra E SOU Marit da ae ees ao VAISS TrOM srs o ad EN 249 What is NetLogo NetLogo is a programmable modeling environment for simulating natural and social phenomena It is particularly well suited for modeling complex systems developing over time Modelers can give instructions to hundreds or thousands of independent agents all operating concurrently This makes it possible to explore the connection between the micro level behavior of individuals and the macro 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 modi
311. to draw so your model runs faster if NetLogo can skip some of them But skipping frames may be bad if the frames skipped contained information that you wanted to see Sometimes the way a model looks when frames are being skipped can be misleading Even when the checkbox is on for a button NetLogo will still skip frames while the code in the button is running Checking the box only ensures that NetLogo will draw a frame when the code is done In some contexts you may want to force NetLogo to draw a frame even in the middle of button code To do that use the display command that forces NetLogo to refresh the view immediately In other contexts you may want to force NetLogo never to draw a frame in the middle of button code only at the end To ensure that put no display at the beginning of the code and display at the end Note also that NetLogo will never draw on screen when inside a without interruption block Turtle and patch forever buttons There is a subtle difference between putting commands in a turtle or patch forever button and putting the same commands in an observer button that does ask turtles oOrask patches 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 and patch forever buttons Since ask was not
312. togram of the agentset using the histogram from command e Use values from 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 the richest turtle is you could say show max values from turtles sum assets e Use turtles from and patches from reporters to make new agentsets by gathering together the results reported by other agents This only scratches the surface see the Models Library for many more examples and consult the Primitives Guide and Primitives 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 Programming Guide 83 NetLogo 3 0 User Manual Code Example Ask Agentset Example Breeds NetLogo allows you to define different breeds of turtles 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
313. ts of other colors don t change For example you could create cars that always have yellow headlights and black wheels but different body colors Shapes Editor Guide 105 NetLogo 3 0 User Manual 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 affected 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 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 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 For example suppose you wa
314. tton or monitor fixed bug where if a chooser had lots of choices some would disappear off the edges of the screen fixed bug where deleting a button or monitor with a syntax error halted the model in saved applets you can now copy from an output area on all web browsers as far as we know fixed bug where a generated movie file could disappear when you quit NetLogo editing a slider switch or choice no longer halts the model unless you change the variable name general miscellaneous improvements to look and feel o What s New 9 NetLogo 3 0 User Manual e HubNet changes new activity Dice Stalagmite improved activity Beer Game Alternate 2 in computer HubNet the Graphics Window tag for receiving mouse events from clients has changed to View existing activities that use this feature must be updated in order to work 4 hubnet message waiting sleeps so HubNet activities don t hog the CPU e Java API changes controlling API can now run BehaviorSpace experiments controlling API now includes new resizeWorld getDrawing getGraphics halt methods 4 fixed bug in extensions API where the unload method was not being called the LogoList and LogoExcept ion classes have been relocated to the org nlogo api package in the extensions API the runonce method in the ClassManager now takes an ExtensionManager which allows the extension to specify that it uses HubNet and also to store an Object that is
315. tual code would be confusing to your users 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 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 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 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
316. tup 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 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 screen edge x and screen edge y and random seed These are not strictly speaking variables but BehaviorSpace lets you vary them as if they were Varying screen edge x y lets you explore the effect of world size upon your model Varying random seed lets you repeat runs by using 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 cis OO SOs OO ONT 108 BehaviorSpace Guide NetLogo 3 0 User Manual Or to give it only the values of
317. u 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 shapes that are included by default in every new NetLogo model ADPRHE I cee oor Soe At 01 ELXOSA A EOX First row default airplane arrow box bug butterfly car Second row circle circle 2 cow face happy face neutral face sad fish Third row flag flower house leaf line pentagon person Fourth row plant square square 2 star target tree triangle Fifth row triangle 2 truck turtle wheel x Shapes Editor Guide 103 NetLogo 3 0 User Manual Shapes library And here are the shapes in the shapes library including all of the default shapes too Creating and Editing Shapes Pressing the New button will make a new shape Or you may select an existing shape and press Edit 104 Shapes Editor Guide NetLogo 3 0 User Manual 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
318. u 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 Calculator amp 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 34 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 Traffic 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 o
319. ucible cross platform e Environment View your model in either 2D and 3D Scalable and rotatable vector shapes Turtle and patch labels 4 Interface builder w buttons sliders switches choosers monitors text boxes What is NetLogo 1 NetLogo 3 0 User Manual Control strip including speed slider Powerful and flexible plotting system Info area 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 BehaviorSpace tool 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 extensions and the 3D view What is NetLogo Copyright Information Copyright 1999 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 sp
320. uption command This ensures that the new turtles cannot interact with any other agents until they are fully initialized In addition no screen updates take place until the commands are done This ensures that the new turtles are never drawn on screen until they are fully initialized sqrt sqrt number Reports the square root of number stamp stamp The calling turtle 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 Primitives Dictionary 241 NetLogo 3 0 User Manual 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 values from turtles energy 7 prints the standard deviation of the variable energy 7 from all the turtles startup startup 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 cct hatch sprout Only the current procedure stops not all execution for the agent 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 foreve
321. urtles on the right half of the screen 5 turn blue 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 200 Primitives Dictionary NetLogo 3 0 User Manual 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 7 the left half of the screen turns red and 7 the right half turns blue ifelse value ifelse value reporter reporter reporter2 Reporter must report a boolean true or false value If reporter reports true the result is the value of reporter If reporter 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 ted 1 the left half of the screen turns red and the right half turns blue show n values 10 ifelse value 2 lt 5 0 1 gt 000001111 1 show reduc ifelse valu 71 gt 72 21 221 1 3 2 5 3 83 22 gt 8 import drawing import drawing filename Reads an image file into the drawing scaling it to the size of the world while retaining the original aspect ratio of the image The image is centered in
322. using an experiment setup saved in the model or specified separately in XML you can create multiple experiment setups and they are saved in your model for later reuse there are now two output format options spreadsheet and table the latter is new and is more suitable for use with statistics and database software you can now use multiple reporters to measure each run you can also use none which is useful if you are recording the results some other way such as with export world 0 you can now vary the world size during an experiment by varying screen edge size x y as if they were variables you can now vary the random seed during an experiment by varying random seed as if it were a variable you can now choose to measure runs only at the end not every tick O you can now vary no variables at all during an experiment this is useful for doing many runs with the current settings e language changes pen and drawing related changes 0 turtle pens draw in the drawing layer instead of changing patch colors as before 0 a turtle s pen if it is down now draws regardless of how the turtle moves even if it s with set xy or jump 0 a pen may also erase using the new pen erase pe command 0 the stamp command now stamps the turtle s shape on the drawing rather than setting the patch color use set pcolor to set the patch color 0 added new commands clear drawing cd import drawing added new turtle variables pen mode and pen size removed
323. uted by repeatedly running reporter In reporter use_ to refer to the number of the item currently being computed starting from zero show n values 5 1 Primitives Dictionary 213 NetLogo 3 0 User Manual gt 1 1 1 1 1 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 14 9 16 See also_reduce filter neighbors neighbors4 neighbors neighbors4 x Reports an agentset containing the 8 surrounding patches neighbors or 4 surrounding patches neighbors4 show sum values from neighbors count turtles here 7 prints the total number of turtles on the eight 7 patches around the calling turtle or patch ask neighbors4 set pcolor red turns the four neighboring patches red netlogo version netlogo version Reports a string containing the version number of the NetLogo you are running show netlogo version gt 3 0 new seed new seed Reports a number suitable for seeding the random number generator The numbers reported by new seed are based on the current date and time in milliseconds and lie in the range 2147483648 to 2147483647 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 214 Primitives Dictionary NetLogo 3 0 User Manual no display no display Tu
324. vities or build your own new HubNet activities e General HubNet Information e NetLogo Primitives Setup Data Extraction Sending Data e Calculator HubNet Information e Computer HubNet Information How To Make an Interface for a Client View Updates on the Clients Plot Updates on the Clients 4 Clicking in the View on Clients Text Area for Input and Display General HubNet Information If you are interested in more general information on what HubNet is or how to run HubNet activities you should refer to the HubNet Guide NetLogo Primitives This section will introduce the set of primitives used to turn a NetLogo Model into a HubNet Activity These commands allow you to send data to and receive data from the clients Setup In order to make a NetLogo model into a HubNet Activity it is necessary to first indicate whether the clients are computers or calculators and then establish a connection between the server your computer and the clients the students calculators or computers using the following primitives hubnet set client interface client type client info If client type is COMPUTER client info is a list containing a string with the file name and path relative to the model to the file which will serve as the client s interface This interface will be sent to any clients that log in hubnet set client interface COMPUTER clients Disease client nlogo when clients log in they will get the interfac
325. w polygon num sides size pd repeat num sides fd size 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 ID number ask turtles draw polygon 8 who Reporter procedures 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 0 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 Programming Guide 77 NetLogo 3 0 User Manual 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
326. work for me Can 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 l install NetLogo on Windows 2003 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 Usage e Can run NetLogo from a CD e How do change the number of patches 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 FAQ Frequently Asked Questions 149 NetLogo 3 0 User Manual e Can import an image into NetLogo e Can import GIS data into NetLogo e My model runs slowly How can speed it up e want to try HubNet Can 1 e Can run a NetLogo model from the command line Can run it without a GUI e Can have more than one model open at a time e Can copy or save a picture of the view e Can I make a movie of my model e Does NetLogo support multiple processors e Can distribute NetLogo model runs across a c
327. xactly the same manner as hubnet broadcast For Computer HubNet it has the following effects 0 When string is the first input this sends value from NetLogo to the tag tag name on the client that has string for a user name O When list of strings is the first input 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 0 All the information for the current state of the View is sent at this time regardless of whether the clients Views were already up to date Note Sending a message to a non existent client using hubnet send generates a hubnet exit message hubnet send view string hubnet send view list of strings For Calculator HubNet does nothing For Computer HubNet it acts as follows 0 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 0 For a list of strings this sends the current state of the 2D View in the NetLogo model to all the Computer HubNet clients that have a user name that is in the list of strings 0 All the information for the current state of the view is sent at this time regardless of whether the clients views were already up to date Note Sending the View to a non existent client using hubnet send view generates a hubnet exit message HubNet Authoring Guide 123 NetLogo 3 0 User Manual When using Calculator HubNet the hubnet send and the hubn
328. xpected 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 Primitives Dictionary 183 NetLogo 3 0 User Manual empty empty list empty string Reports true if the given list or string is empty false otherwise Note the empty list is written The empty string is written end end Used to conclude a procedure See to and to report 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 at most every number seconds 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 every only limits how often the commands run More technically its exact behavior is as follows When an agent reaches an every it checks a timer to see if the given amount of time has passed since the last time the same agent ran the commands in the every in the same context If so it runs the commands otherwise they are skipped and execution continues Here in the same context means during t
329. y e The stop and report commands do not work properly if used inside without interruption we are already working on fixing this e If you use Export World to suspend a model run and then resume it later with Import World this may change the outcome of the model run if your model involves turtles dying and new turtles being born because the export import may change what who numbers get assigned to new turtles we are already working on fixing this e Export World does not include the contents of plots we are already working on fixing this e Extensions 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 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 Macintosh on
330. y facexy nowrap facexy number number facexy nowrap number number Set the caller s heading towards the point x y If the wrapped distance around the edges of the screen is shorter than the on screen distance facexy will use the heading of the wrapped path facexy nowrap never uses 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 myfile 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 Primitives Dictionary 187 NetLogo 3 0 User Manual 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 file delete file delete string Deletes the file specified as string string must be an existing file with writable permission by the use
331. y nsum nsum4 of patch patch at patch ahead patch at heading and distance patch here patch left and ahead patch right and ahead patches patches from patches own self sprout sprout BREED subject value from Agentset primitives any ask at points BREED at BREED here BREED on count histogram from in cone in cone nowrap in radius in radius nowrap is agent is agentset is patch agentset is turile agentset max one of min one of neighbors neighbors4 one of other turtles here other BREED here patches patches from random n of random one of turtles with with max with min turtles at turtles from turtles here turtles on values from Primitives Dictionary 167 NetLogo 3 0 User Manual Color primitives color extract hsb extract rgb hsb import pcolors pcolor rgb scale color shade of wrap color Control flow and logic primitives and 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 without interruption xor World primitives clear all ca clear drawing cd clear patches cp clear turtles ct display import drawing import pcolors no display no label screen edge x screen edge y screen size x screen size y Perspective primitives follow follow me reset perspective rp ride ride me subject watch watch me HubNet primitives hubnet broadcast hubnet broadcast view hubnet enter message hubnet exit message

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