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NetLogo 2.0.2 User Manual - Center for Connected Learning and

1. 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 41 42 NetLogo 2 0 2 User Manual Tutorial 2 Commands 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 calle
2. 104 HubNet Authoring Guide NetLogo 2 0 2 User Manual 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 sourc will contain 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 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 Note Si
3. e Wait until the setup button pops back up in other words turns blue again e Press the go button to start the simulation As the model is running what is happening to the wolf and sheep populations e Press the go button to stop the model Controlling the Model Buttons When a button is pressed the model responds with an action A button can be a once button or a forever button You can tell the difference between these two types of buttons by a symbol on the face of the button Forever buttons have two arrows in the bottom right corners like this Once buttons don t have the arrows like this Once buttons do one action and then stop When the action is finished the button pops back up Note If you do not wait for the button to pop back up before pressing any other buttons the model might get confused and you may get an error message 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 I
4. 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 gt ba 192 Primitives Dictionary NetLogo 2 0 2 User Manual 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 Bob 7 set mylist remove duplicates mylist 5 mylist is now 2 7 4 Bob remove item remove item index list remove item index string For a list reports a copy of ist 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 7 the turtle draws a circle replace item replace item index list value replace item
5. 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 Primitives Dictionary 151 NetLogo 2 0 2 User Manual 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 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 expected it s because in NetLogo a heading of 0 is north and 90 is east which is the reverse of how angles are usually defined in geometry Note In earli
6. 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 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 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 the agent in the agentset that reports the lowest value for the given reporter show min one of turtles xcor ycor 7 reports the turtle with the smallest sum of 7 its coordinates Primitives Dictionary 175 NetLogo 2 0 2 User Manual 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 1 See also remainder mod and remainder behave the same for positive n
7. NetLogo 2 0 2 User Manual NetLogo 2 0 2 User Manual Table of Contents What IS od Ro o 6 PAR T A vucenaac roses RR SR RD MERDA ARE RR 1 ESTO uri E RS RO NS NO RR ed 1 Copyright Information a 3 What s New2 a dalt ida 5 Version 2 0 2 August 6 2004 ococccccccccccncconononnnnnnnnnnnnnonnnonnnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnnnnrnnenineness 5 Version 2 0 1 May 7 2004 ooooccocccncncnnnonnnonononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnineniss 6 Version 2 0 0 December 10 20038 oooccccconcnccnccococonccocononncnoncnnnononcnnnononcnnonnoncnnnnnononennnnnanenanons 7 Version 1 3 1 September 2003 hidra 10 Versioniti3 June 200 rss aid 11 Version 1 2 March 2003 oocccoconcccccccocnnccococoncnnoncononnononnnnnononnnnnononrnnnononrnnnnnonrnnnnnencnninnonannnnns 11 Version 1 1 July 2002 unan iaa cil 11 Version 1 0 Aprii20O0 iia A dal aaa 12 System Requirements iii iia 13 System Requirements ApplicatiON oooooccccccnonnooonncnnnnnnonnnonnnnnnnnnnncnconnn ono nnnnnnccnnnnrnnnnnnnnnnn 13 WINAOWS du sans sas uia nal a A a EE EA ce euty 13 MacOS ti tt tai 13 Mac OS 8 and 9 ataca a da DO A e A a ds o a O e Re 13 Oth r platos ci aaa 13 System Requirements Saved AppletS ccccooonooocccccocccoccnononncncnnnnccconannnnonnnnnccnnnnnnnnnnnnnnnnns 13 Known issues cut aia ani lonas 15 Known bugs all SYSteMS ee 15 Windows o nly DUQS ovio 15 Macintosh on ly DUAS saias easier E dE CU ETA ER
8. NetLogo 2 0 2 User Manual 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 breed breed x 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 breeds Example breeds cats dogs 7 turtle code if breed cats show meow set breed dogs show woof Primitives Dictionary 143 NetLogo 2 0 2 User Manual 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 br
9. count turtles turtles user yes or no user yes or no value Reports true or false based on the user s response to value value may be of any type but is typically a string if user yes or no Set up the model setup V 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 Primitives Dictionary 211 NetLogo 2 0 2 User Manual 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 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 Del W wait 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
10. 148 Primitives Dictionary NetLogo 2 0 2 User Manual 7 all turtles with xcor greater than 20 die See also _ct diffuse diffuse patch variable number gt 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 ig Like diffuse but only diffuses to the four neighboring patches to the north south east and west not to the diagonal neighbors diffuse4 chemical 0 5 7 each patch diffuses 50 of its variable 77 chemical to its neighboring 4 patches Thus each patch gets 1 4 of 50 of the chemical from each neighboring patch display display Causes the graphics window to be updated immediately Also undoes the effect of the no display command so that if display updates were suspended by that command they will resume no display ask turtles jump 10 set color blue set size 5 display turtles move change color and grow with none of 5 their intermediate states vis
11. A variable can be a global variable a turtle variable or a patch variable If a variable is a global variable there is only one value for the variable and every agent can access it But each turtle has its own value for every turtle variable and each patch has its own value for every patch variable Some variables are built into NetLogo For example all turtles have a color variable and all patches have a pcolor variable The patch variable begins with p so it doesn t get confused with the turtle variable If you set the variable the turtle or patch changes color See next section for details Other built in turtle variables including xcor ycor and heading Other built in patch variables include pxcor and 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 exampl
12. Frequently Asked Questions 127 NetLogo 2 0 2 User Manual Unlimited numbers of agents and variables Double precision arithmetic AR E ES X Simplified language structure Agentsets make many programming tasks easier NA ESC Ea Exact on screen turtle positioning x Redesigned user intertace SSS x Text labels for turtles and patches S x Many new primitives o x APlforuserextensions S x API for controlling NetLogo from outside x _ BehaviorSpace a tool used to collect data from multiple runs of a model x _ HubNet participatory simulations using networked devices Has anyone written 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 2 0 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 f your model uses random numbers then in order to get reproducible behavior you must use the random seed command to set the random seed 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 comput
13. 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 FAQ Frequently Asked Questions 133 NetLogo 2 0 2 User Manual 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 Does NetLogo have a command like StarLogo s grab command We don t have such a command although we plan to add one or perhaps several In the meantime though you can use the without interruption primitive to arrange exclusive interaction between agents For example turtles own mate to setup ask turtles set mate nobody end to find mate turtle procedure locals candidate without interruption if mate nobody set 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 turt
14. 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 Currently there are two implementations of HubNet calculator HubNet and computer HubNet Calculator HubNet uses Texas Instruments calculators and requires TI s calculator network system called_Navigator Unfortunately the version of Navigator which is currently commercially available does not support HubNet In the future we hope that calculator HubNet will be supported on a commercially available version of Navigator Computer HubNet uses networked computers and does not require calculators or Navigator Computer HubNet is included in the NetLogo download and can be used without additional materials Please refer to the HubNet Guide for more information on computer HubNet Can run a NetLogo model from the command line Can run it without a GUI FAQ Frequently Asked Questions 131 NetLogo 2 0 2 User Manual At present there is no way to run without the GUI We plan to add this in a future version On X11 based systems such as Linux
15. iii ad 198 set d fa ult sha Ps ci si 199 set hiStograM NUM bDAS coococococcconononnoonnno nono n nono non css nn nnnnnnn nro nono nn non nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnos 199 SEt PlOt P ON COlON ee eee eeeecececceeceeeceeeceeeeee non cics sete crono rro nnn nn nn nn nn nn nn nn nn nn nn nn nn nnnnnnnnos 199 s t plot pen interval nsien ena ia aeh ea eaa rro nro n nn nn nn nn nn nn nn nn nn nn nn oaei 200 SEITE MO ias iia ia 200 set plot x range Set plol Y 1ANQl oooccccccccooccoononononononononnno nono nononnnnn nono nnnnnnnnnnnnnnnonnnnnnos 200 SN st A caco 200 Shade O nt re aa 200 Mes 201 SA PA AN 201 SHOWIUMIG S da 30244 EN a DA 2 A ee A a 201 A a ee 201 MM A ER SAR aac ta PAR cad RE OR PR 202 A O te 202 O 202 NetLogo 2 0 2 User Manual Table of Contents Primitives Dictionary SOR DY SN aiken RA 202 A ees cues heen ea aed erect econ eed hind segs deed rea bead ety Mata Danda eb ia hated taninos 203 A A O 203 A ah ree es eee hee ea le RL RR NR 203 standard devialiOn ici PP ST 203 SID ei A RR EDER 204 A 204 SUD iaa in 204 MM aio 204 A A O O 204 LA O A a De A TS Gd EA fas 205 ON E 205 O A A A 205 KORE NO 205 towards tOWALAS NOW AN cee ceecceecceecceeeceeeceeeeceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeteeeeeeeeeeeeeeeteeeeneeees 206 towardsxy tOWardSXY DNQWIAD occccccccccnccnnnnnnnnnnnnnnnnnnnnnnnnnnnrrnrrr nr rre 206 CNEL ce eB ate ered scarey o Soe ae eta RREO ODE SN RDNS ved detente 206 UE a ds dd da
16. jar NetLogo jJar 130 FAQ Frequently Asked Questions NetLogo 2 0 2 User Manual Can import a graphic into NetLogo At present this capability is not built in We plan to add it in a future version In the meantime though there are some possible solutions One is to convert the image data into a format that import world can understand then import it that way Another is to read and translate the image data yourself using file open and file read characters You may wish to first use another program to convert the image into a format that is easier to read that way such as PBM 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 display update after each run checkbox This allows the graphics window to skip frames which may speed up models which are display intensive See the Buttons section of the Programming Guide for a discussion of this e Use the display switch in the graphics control strip or the no display command to turn graphics off temporarily For example to go no display disp ias end e If your model is using all available RAM on your computer then installing more RAM should help If your hard drive makes a lot of noise while your model is running you probably need more RAM In many cases though if you want your model to run faster you may need to make some changes to the code
17. sprout 1 Programming Guide 73 NetLogo 2 0 2 User Manual 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 histogram 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 Code Exampl
18. though one possible workaround is to use X11 s virtual frame buffer feature which provides a virtual display for NetLogo to run on To open a model on startup you can just pass the open flag followed the pathname of the model on the command line as an argument to the executable Examples e Windows C Program Files NetLogo 2 0 NetLogo 2 0 exe open C myfiles mymodel nlogo e Mac OS X Applications NetLogo 2 0 NetLogo 2 0 app Contents MacOS NetLogo open Users me mymodel nlogo e Linux et al cd netlogo 2 0 java jar NetLogo jar open home me mymodel nlogo If you want the model to actually start running automatically once opened you have two options The easiest option is to add a procedure to the Procedures tab called startup For example to startup Setup repeat 100 go export world word get date and time csv end You can put any code you want in the startup procedure If you need to do something more sophisticated or if you don t want to have to add code to your model then a more advanced option is to use NetLogo s Java API for controlling NetLogo from external Java code See the Controlling section of the NetLogo User Manual for details Note that some light Java programming is required in order to take advantage of this API Can I have more than one model open at a time One instance of NetLogo can only have one model open at a time We plan to change this in a future ver
19. 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 turtleset containing one turtle from 7 each patch that has any turtles on it turtles from neighbors turtles here if run by a turtle or patch reports the set of all turtles on the neighboring eight patches note that 7 this could be written more concisely using turtles on 7 like this a turtles on neighbors See also patches from turtles on turtles here BREED here turtles here BREED here Reports an agentset containing all the turtles on the caller s patch including the caller itself if it s a turtle Primitives Dictionary 207 NetLogo 2 0 2 User Manual ca ert 10 ask turtle 0 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 gt 5 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 tur
20. 134 FAQ Frequently Asked Questions NetLogo 2 0 2 User Manual concurrently In these situations appropriate use of without interruption can be helpful How can use different patch neighborhoods circular Von Neumann Moore etc The in radius primitives lets you access circular neighborhoods of any radius The neighbors primitive gives you a Moore neighborhood of 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 The usual technique is to create a new breed of turtle whose shape is a line and position and size that turtle appropriately so that it appears to connect the two turtles you want to connect We plan to support this more directly in a future version of NetLogo How can 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 con
21. 2 0 2 User Manual 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 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 die die The turtle dies if xcor gt 20 die
22. 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 want 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 Cre 50 And then give these commands to the turtles to spread them out then change their shape fd random 15 set shape rabbit Voila Rabbits Note the use of double quotes around the shape name The set default shape command is also useful for assigning shapes to turtles 88 Shapes Editor Guide BehaviorSpace Guide This guide is broken up into three parts e BehaviorSpace Old and New An explanation of how BehaviorSpace changed between NetLogo 1 3 and 2 0 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 BehaviorSpace Old and New For NetLogo 2 0 the old BehaviorSpace tool from NetLogo 1 x was replaced with a new rewritten version which though functional is still under development The new version does not yet include all the functionality of the old one The biggest difference is that it does not include any of the data analysis capabilities the old version had Instead it is assumed that you will use other software Such as a spreadsheet program or scientific visualization to
23. Interface Elements Selecting To select an interface element drag a rectangle around it with your mouse A gray border will appear around the element to indicate that it is selected Selecting Multiple Items You can select multiple interface elements at the same time by including them in the rectangle you drag If multiple elements are selected one of them is the key item which means that if you use the Edit or Delete buttons on the Interface Toolbar only the key item is affected The key item is indicated by a darker gray border than the other items Unselecting To unselect all interface elements click the mouse on the white background of the Interface tab To unselect an individual element control click 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 Interface Guide 61 NetLogo 2 0 2 User Manual 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
24. O TS SS a 173 OO estadas Sa a aaa 173 DU asteri caio da SN de A ARO ES 173 A Ege ssa do aa ea SAL bas olle dto DE 173 MAD estas a eder Sa DA apaga paga aaa 173 MAX vee aceon ends under asas iscas A ad 174 MENEE i c3 A tos e a O A e ES TA or 174 A A E ee ee ree 174 MAMA TRA AA ee ae ee ee 175 MeEmbeR esate NA 175 ga a Beer ae o a et Da cn A des ers ae e ro 175 vii NetLogo 2 0 2 User Manual Table of Contents Primitives Dictionary viii TAT a o gt dai A a A E O ETT 175 Madonnan ven teen Wank fares ute aden db uited Needs sete aden Mamet O EUA DR en Mates UA 176 MmOdES LAA io E AS A AA BO BAe A ato Ao RA AS A ACAI A 176 MOUSE GOWN2s sta sine sia A aa seca 176 MOUSO XCOF MOUSC VCOL iva le 177 SO A A Aa 177 A e a a e odia ana one 177 A da a a ee 177 neighbors NEIGHDOIS4 inician ca a cad 178 NO CISDIAY 2 02 i e aean e aradstendterseeanedca DOR RR RR 178 No label 4 e A TA ud 20 o da ada At Oech ST Ad TA ad Lee he 178 NODO ARA RP ERP RR ERR NARRA RP OR O 179 MO A E VR O a eet SRU 179 FAS ESAS UIT a do O ia als pias ci GE pa CABER Dt ta ad 179 A den mus cal en eo chit eS ibe de doada do E a Ie nad alot cido E E ENO EEE SEE 180 E O RR RR SRA O ARC iO 180 ONO ORS oh RIR A SANDER ORNE END DRE NETO DUO NDA RR AS 180 o E SRD A A sr 180 other turiles here other BREED here streets renan 180 A EEE E RO NOR DNA E DRE SAR RO PRE PRE RN RR NR A NE ET 181 o sia es Seade ii a N N SETA eR IN atc aber 181 paich ahea
25. ORIN 164 DUDA CIDO ACA sete asda ecuador enn aie ee deco a Di ad 164 hubnet o6nter Message einet ee ae lada 164 RUDO MESS AO a E A 164 hubnet fetch message reias nrnnnnnnnnnnnnnnrrrnnnnnnnnnnnnnnnrnnnnrnninnnnnos 165 hubnet EET O e E E E adas 165 NUbNet MESSAGE SOUICE cccccccccseceeeccaecceceeeceeecececeneceeeceeeccaecceceeeceeeeeeeeseneseeeeeneeeees 165 DUDNet MESSage taQ cccccccccncconcnonononononononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnineninnnnss 165 hubnet Message WaltidQ oooococonnnccccnonooooonnnnccnnnnnnnnonnnnnnnnnnnnnnnonrnnnnnnnnrnnnnnn no rnnnnreninnnnos 165 DUDA CIS ld 166 NUDASIESENA E AA AA ee ee A A eee 166 hubnet set client inter ace occcccccncccccncnoccnnnononcnononononononanananononannnononannnn nana antennen canas 166 A A A EEPE CAE eons Niue Me ts de TESE T a 167 a A AR A ia 167 TONS Qe ars A AN ad ss SDS a a Rad 167 felse ValWBs ted vee tasa 168 anjo WOT cErRE dic 168 in radius in radius nowrap ee eeeeeeeaeraaeaaaaaaaaaana nana nanaranaranananaaana 169 ASPE naaa aaa 169 O 169 is agent is agentset is boolean is list is number is patch is patch agentset is string is turtle is turtle agentset 169 AAA a re A 170 A A A RT 170 A DR E E E 170 NAT 171 ADA A A IN AAA A IR E 171 EA A ON 171 e TE TA e a A 171 lt dl T E 172 OMA 172 MS at unas 172 Mera is A a A RA AA A O A o le 172 A o GUS RN 6 MD Na Ed Sri 172
26. User Manual e engine fixes fixed bug in the at points reporter that could cause an agentset with duplicates in itto be returned fixed obscure bug in the die command that caused some models such as Gas Chromatography to behave incorrectly What s New NetLogo 2 0 2 User Manual fixed bug where correct code using the reduce primitive would sometimes fail to compile fixed bug in Import World where if the import file contained the empty string the built in variable would be set to 0 0 without notifying the user this bug should only have affected users who edited a world file using another application e interface fixes compiler now gives a clearer error message if you try to use a non ASCII character in an identifier non ASCII characters are now permissible in some other contexts such as in strings where they weren t in NetLogo 1 3 fixed obscure bug where occasionally models were saved with turtle shapes in a format that couldn t be loaded on certain Java virtual machines fixed bug where hitting the close box in the dialog that opens when creating a new widget in the interface tab could cause a Java exception Version 1 3 June 2003 e graphics window control strip e choice widgets e Export World now inter operates properly with Excel and other programs e Edit menu now has items for commenting indenting e redesigned interface toolbar e strict math mode so results are identical on all platforms requires
27. a a RS labia Maen A ENEA 191 RES IE E Cos A A A ad E 191 EMANAN E Eola ae 192 TOMO ida 192 remove duplicates ooccccccccccconcnoncnnncnoncnnnonnncnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnnnnnnoss 193 FEMOVOE E ESI AREE tes de E Ok ye a o TE EA ui 193 POD SAL EEEE tua Moda ada doada Sun alia ne LE hs LOU aa SD dana AS Dica nada das led do dada aaa ada da dei 193 replaced Mia A dental av teh Ad 193 Odin A tne ed ee ta 194 A A A 194 AA E aeRO Ed O CO 194 A ET E E E 194 PQ A EAE E EA ERR E RR A RR E E 195 OUNAE A A O A aS A As R Do O A RR REET 195 EA EN DE PR RR T NPR ASS DO PA NR RR CRE DEN RD RR DOR PR E RS 195 HUMES UE soar os Ae che Recetas EN dA AA Ra SS Ga AE atl 195 PO ae ta a ea ua e a TB Aa o SU da pa Mais Sean cain Mata aad 196 SCAG HR CONOR seg es fect DE RO RU RR RR ERR es 196 screen edge x screen edge 4 lllllllli nnnnnn nono nono nono nonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnns 196 ANA eee eeeecececcceeeceeceee cece eeeeeeeaeeeaeaeeeeaeeeaeeeseeeqeeeseenseeneeesseenes 197 SO a cee recast TEE E A EEEE EAT ASN a qa 197 ASE MICOLON ias castro neta tant DEAR O E E ENE 197 Sent ncerse ecb etch tert hostess tela te URCA E soa Gia Ra Gba et a O wet hia Maks NO a a o 197 Si al AD AN Soca a dl 198 set current dIreCLOry s menisco rss insinico ines siesta rn daa nd i a eee sa aee dan end da nina Nani andina andado 198 U LELDE ONON REA EE E ii cee E E nn rn rra nn nn nn nn nn nn nnnnnnos 198 set current ploi Pen
28. 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 Predation time ticks sheep wolves grass 4 0 0 0 0 The monitor labeled time ticks tells us how much time has passed in the model The other monitors show us the population of sheep and wolves and the amount of grass Remember the amount of grass is divided by four to keep the graph 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 Tutorial 1 Models 27 NetLogo 2 0 2 User Manual introduced in Tutorial 2 Controlling the Graphics Window If you look at the graphics window you ll see a strip of controls along the top edge The control strip lets you control various aspects of the graphics window 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
29. a row It does not return the line terminator characters Also note that the file open command must be called before this reporter can be used and there must be data remaining in the file Use the reporter filge at end to determine if you are at the end of the file file open myfile txt print file read line gt Hello World See also file open file show file show value Prints value to an opened file preceded by the calling agent and followed by a carriage return The calling agent is included to help you keep track of what agents are producing which lines of output 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 fle type and file write 158 Primitives Dictionary NetLogo 2 0 2 User Manual 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 nobod
30. 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 L show gt round With multiple lists runs commands for each group of items from each list So they are run once for the first items once for the second items and so on All the lists must be the same length In commands use_ 1 through_ n to 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 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 _ 160 Primitives Dictionary NetLogo 2 0 2 User Manual 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 fd 3 takes three See also_jump fput fput tem list Adds item to the beginning of a list and reports the new list 7 suppose mylist is 5 7 10 set mylist fput 2 mylist 7 mylist is now 2 5 7 10 G get date and time get 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
31. 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 senda generates a hubnet exit message See the HubNet Authoring Guide for details hubnet set client interface hubnet set client interface client type client info If client type is TI 83 client info is a list containing two items The first item is a string containing the name of the activity to enable on the TI Navigator web site hubnet set client interface TI 83 notifies the user to enable this activity The second item is a list of the tags for which to check The tag list sets which variables NetLogo expects from the calculators NetLogo will only check for these variables and will ignore all others If client type is COMPUTER client info is a list containing a string with the file name and path 166 Primitives Dictionary NetLogo 2 0 2 User Manual 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 MT L83t AAA Gridlock 1 3 L1 LOCS 7 notifies th
32. be applied to almost any subject What other emergent phenomena can you think of To see more examples and gain a deeper understanding of this concept and how NetLogo helps learners explore it you may wish to explore NetLogo s Models Library It contains models that demonstrate these ideas in systems of all kinds For a longer discussion of emergence and how NetLogo helps learners explore it see_ Modeling Nature s Emergent Patterns with Multi agent Languages Wilensky 2001 What s Next The section of the User Manual called_Tutorial 1 Running Models goes into more detail about how to use the other models in the Models Library If you want to learn how to explore the models at a deeper level Tutorial 2 Commands will introduce you to the NetLogo modeling 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 22 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 the
33. 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 Looking at some of the sample models and code examples in the Models Library may help as well NetLogo 1 3 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 NetLogo 2 0 so if you have models you want to use it on you will have to use NetLogo 1 3 to do the conversion then open the model in 2 0 If you need any help converting your StarLogo or StarLogoT model to NetLogo please feel free to get in touch with us at_feedback ccl northwestern edu The_NetLogo Users Group is also a good resource for getting help from other users 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 I 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 If you want the world to be a bounded rectangle you may need to add some code to your model to enforce this
34. by combining basic geometric figures 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 create a new shape edit copy or delete an existing shape or import shapes from other models Creating and Editing Shapes Pressing the New button will cause a new shape to be created and the editing window will appear allowing you to name and make the shape The shape you make will appear in the main drawing area and in the three smaller preview areas found on the left side of the editing window The preview areas show your shape at different sizes as it might appear within your model as well as how it looks while rotating The rotatable feature can be turned off if you want a shape that does not rotate as the turtle s heading changes There are four drawing tools select from four button icons each of which can be filled with color or not and a background grid to guide you You can move and size these basic shapes with the mouse pointer as a drawing tool The basic geometric figure created last will fall on top Geometric figures can be removed one at a time with the Remove Last button The Remove Last and Remove All buttons are the only way of correcting mistakes you can t go back to move or alter a geometric fig
35. can be compared using the lt gt lt and gt operators To concatenate strings that is combine them into a single string you may also use the plus operator like this Programming Guide 83 NetLogo 2 0 2 User Manual tur Ele gt turtle If you need to embed a special character in a string use the following escape sequences e n newline carriage return e t tab e double quote e backslash Turtle shapes In StarLogoT turtle shapes were bitmaps They all had a single fixed size and could only rotate in 45 degree increments 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 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 Use the Shapes Editor to create your own turtle shapes For more information see the Shapes Editor_section of this manual Code Examples Breeds and Shapes Example Shape Animation Example File I O In NetLogo there are a set of primitives that give the user the power to interact with outside files They all begin with the prefix file There are two main modes when
36. 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 e evation will result in darker shades The only part remaining in our new setup that is still undefined 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 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 48 Tutorial 3 Procedures NetLogo 2 0 2 User Manual Press setup again looks differe
37. cp clear turtles ct display no display no label screen edge x screen edge y screen size x screen size y HubNet primitives hubnet broadcast hubnet enter message hubnet exit message hubnet fetch message hubnet message hubnet message source hubnet message tag hubnet message waiting hubnet reset hubnet send hubnet set client interface Input output primitives clear output export graphics export interface export output export plot export all plots export world get date and time import world mouse down mouse xcor mouse ycor 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 fle 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 values from 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 ite
38. don t want them to move randomly about We want each turtle to look at the e evation 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 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 J 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
39. 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 Primitives Dictionary 199 NetLogo 2 0 2 User Manual 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 set plot pen mode number Sets the mode the current plot pen draws in to number The allowed plot pen modes are e 0 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 mode for new pens is 0 line mode set plot x range set plot y range set plot x range min max set plot y range min max Sets the minimum and maximum values of the x or y axis of the current plot The change is temporary and is not saved with the model When the plot is cleared the ranges will revert to their default values as set in the plot s Edit dialog setxy setxy xy The turtle sets its x coordinate to x and its y coordinate to y Equivale
40. enter You should then follow the instructions for the particular model found in the QuickStart Instructions monitor Most models will require you to press a forever button often called GO You as the leader should notify everyone that they may join For them to join you should give them the IP address for the computer that is running NetLogo The IP address of the server can be found in the HubNet Control Center which can be opened by choosing the HubNet Control Center option in NetLogo s Tools menu Every user will have to enter this IP address to be able to enter the activity On some systems the HubNet Client will automatically detect all the Computer HubNet activities currently being run On these systems instead of typing in the IP address everyone can select the activity from a list Each item in the list should contain the unique name you entered in the dialog when you first opened the HubNet model followed by the name of the activity followed by the IP address of the computer running NetLogo Every participant will also have to enter a unique user name If a participant types in a user name that someone else is already using they will be asked to choose a different name Joining a Computer Activity Once the leader has informed you that you can join you should open up the HubNet Client application This will prompt you for the IP address of the computer running NetLogo Enter the IP address that the leader gave you Alternately if
41. every 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 LEIL 7 turtle moves until it finds a patch that has 212 Primitives Dictionary NetLogo 2 0 2 User Manual 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 this variable a turile s id number never changes 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 cct 100 ifelse who lt 50 set color red set color blue 7 turtles 0 through 49 are red turtles 50 7 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 age
42. 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 I 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 it via Get Info in the Finder I m on a UNIX system and I can t untar the download Why Some of the files in the tarball have very long pathnames too long for the standard tar format You must use the GNU version of tar instead or another program which understands the GNU tar extensions On some systems the GNU version of tar is available under the name gnutar You can find out if you are already using the GNU version by typing tar version and seeing if the output says tar GNU tar Applets tried to run one of the applets on your site but it didn t work What should do The applets on the CCL web site have been upgraded to use NetLogo 2 0 which requires that yo
43. fixing this e file open doesn t work from models saved as applets we are already working on fixing this e Extensions don t work from models saved as applets we are already working on fixing this Windows only bugs e The User Manual item on the Help menu does not work on every machine Windows 98 is more likely to be affected newer Windows versions less so Macintosh only bugs e When opening a model from the Finder by double clicking on it or dragging it onto the NetLogo icon if NetLogo is not already running then the model may or may not open the bug is intermittent If NetLogo is already running the model always opens e On OS X 10 2 the User Manual item on the Help menu will sometimes launch a web browser other than your default browser Linux UNIX only bugs e User Manual always opens in Netscape not your default browser suggested workaround bookmark the file docs index html in your favorite browser e We have discovered a problem where the exp reporter sometimes returns a slightly different answer differing only in the last decimal place for the same input 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 we have determined that the problem is a bug in the Sun s Java VM and not in NetLogo itself we have reported the problem to Sun and are awaiting a response we hope that only the exp reporter is affected but we c
44. from patches own patches own var1 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 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 Primitives Dictionary 183 NetLogo 2 0 2 User Manual pen down pd pen up pu pen down pen up The turtle its pen down or up so that it draws leaves a trail when they move or doesn t Turtles draw by changing the color of the patches underneath them to their own color To change the color of the turtle s pen and the color of the turtle itself use set color Note When a turtle s pen is down only the commands forward and back cause drawing Note Theses commands are equivalent to setting the turtle variable pen down to true or false See also pen down pen down pen down This is a built in turtle variable It holds a boolean true or false value indicating whether the turtle s pen is cu
45. given reporter is run for each group of items from each list So it is run once for the first items once for the second items and so on All the lists must be the same length In reporter use_ 1 through_ n to refer to the current item of each list Some examples make this clearer show map 1 2 1 2 3 2 4 6 gt 3 6 9 show map 1 2 3 1 2 3 2 4 6 3 5 9 gt true false true See also foreach 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 show max one of patches count turtles here 7 prints the patch with the most turtles on it 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 174 Primitives Dictionary NetLogo 2 0 2 User Manual 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
46. 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 correctly 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 O 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 Another common tool to see what s going on is to write T 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 Tutorial 43 Procedures 51 NetL
47. has a higher percentage of people of the opposite sex than their tolerance allows then they become uncomfortable and leave the group to find another group For example if the tolerance level is set at 25 then males are only comfortable in groups that are less than 25 female and females are only comfortable in groups that are less than 25 male As individuals become uncomfortable and leave groups they move into new groups which may cause some people in that group to become uncomfortable in turn This chain reaction continues until everyone at the party is comfortable in their group Note that in the model tolerance is not fixed You the user can use the tolerance slider to try different tolerance percentages and see what the 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 Graphics Window 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
48. 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 Applets e tried to run one of the applets on your site but it didn t work What should do Usage e How do change the number of patches e How big can my model be How many turtles patches procedures buttons and so on can my model contain e Can import a graphic 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 graphics window e Can make a movie of my model Programming e How is the NetLogo language different from the StarLogoT language How do convert my StarLogoT model to NetLogo FAQ Frequently Asked Questions 125 NetLogo 2 0 2 User Manual 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 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 Can
49. high and low fitness that is sets of neighboring near black and near blue squares The landscape represents a 2 dimensional plane in the multi dimensional parameter space of the model since it accounts for all possible values of two sliders while the rest are held constant By changing the values of any constant sliders you are shifting that 2 D plane through the parameter space and by selecting new sliders to be the axes you are selecting a new plane entirely that is a plane through different dimensions e As you move your mouse over different squares in the grid the data from those runs will appear in the behavior plot to the left in addition to the line or curve that best fits the data if the add best fit line checkbox is selected e As your mouse passes over a square in the landscape information about the model run that square represents appears above the landscape This information consists of the value that each of the two selected sliders had during that run and the overall fitness of that run e The fitness of a run is an estimation of how good the run was according to the criteria you select in the menus listed above When the slope checkbox is selected fitness derives from the slope of the data as well as how well it fits a linear or exponential curve You can control the relative importance of these factors with the relative weight menu When the point statistic checkbox is selected the value that you see above the landsc
50. 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 7 Suppose mylist is 2 4 6 8 10 show item 2 mylist gt 6 show item 3 my shoe gt g 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 170 Primitives Dictionary NetLogo 2 0 2 User Manual L label label k This is a built in turtle variable It may hold a value of any type The turtle appears in the graphics window 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 color plabel plabel color Example ask turtles set label who 7 all the turtles now are labeled with their id numbers ask turtles set label no label all turtles now are not labeled label color label color This is a built in turtle vari
51. 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 computed by repeatedly running reporter In reporter use_ to refer to the number of the item currently being computed starting from zero Primitives Dictionary 177 NetLogo 2 0 2 User Manual show n values 5 1 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 1 4 9 16 See also_reduce filter neighbors neighbors4 neighbors neighbors4 Reports an agentset containing the 8 surrounding patches neighbors or 4 surrounding patches neighbors4 show sum values from neighbors count turtles here 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 no display no display Turns off all updating of the graphics window until the display command is issued This has two major use
52. in turtle variable It holds the color of the turtle You can set this variable to make the turtle change color See also_pcolor 146 Primitives Dictionary NetLogo 2 0 2 User Manual cos cos number Reports the cosine of the given angle Assumes the angle is given in degrees 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 w 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 create custom turiles number commands create custom lt BREED gt number commands 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 Primitives Dictionary 147 NetLogo
53. 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 show replace item 2 2 7 4 5 15 gt 12 7 15 5 show replace item 1 sat lo Primitives Dictionary 193 NetLogo 2 0 2 User Manual 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 See to report for a discussion of how to use them 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 7 mylist is 2 7 4 Bob set mylist reverse mylist 7 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 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 descri
54. of numbers in the list 1 1 it would be done as follows Set the value of the list to some numbers in this case 20 A and B where A and B are number variables that are set previously in the calculator code Then write 20 A B gt L1 1 L1 gt Stro Asm prgmSENDVAR The length of the list of numbers that a calculator sends depends on what information you want to send to the NetLogo model Further how those numbers are interpreted by the model is also up to you You can also receive data from the NetLogo model To do this use the following calculator code 106 HubNet Authoring Guide NetLogo 2 0 2 User Manual 4 Str6 1 gt Strod Asm prgmGETVAR Let s take a look at how the values of the string stro are set The first input in the string represents the type of variable that you are trying to get Since we are trying to get a string Str 6 we give the first input the value 4 See below for the values of legal data types The second input is the variable in which you would like to save the data received In this case we want to save the data to the variable str6 The third input tells how you would like to save this data into this variable See below for values of valid commands It should be noted that for sending a variable the command defaults to 0 i e no command data type number 0 list of numbers 1 command number command explanation 0 No Command 1 Collate Lists into a matrix real
55. 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 154 Primitives Dictionary NetLogo 2 0 2 User Manual 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 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 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 Primitives Dictionary 155 NetLogo 2 0 2 User Manual file close all file close all Closes all files if any that have been opened previously with file open S
56. or straight left and right Resizing Select the interface element then drag the black handles in the selection border Deleting Select the element or elements you want to delete then press the Delete button on the Interface Toolbar You may also delete an element by control clicking Macintosh or right clicking other systems it and choosing Delete from the popup menu If you use this latter method it is not necessary to select the element first To learn more about the different kinds of interface elements refer to the chart below Chart Interface Toolbar Description Buttons can be either once only buttons or forever buttons When you click ona 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 slider Sliders are global variables which are accessible by all agents They are used in models as a quick way to change a variable without having to recode the procedure every time Instead the user moves the slider to a value and observe what happens in the model E 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 Choices let the user pick a value for a global variable from a list of choices presented in a drop down menu Monitors display the value of any expression The expression cou
57. pen named penname a string If no such pen exists in the current plot a runtime error occurs 198 Primitives Dictionary NetLogo 2 0 2 User Manual set default shape set default shape turtles string set default shape breed string 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 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 77 new turtle s shape is default set default shape turtles circle create turtles 1 new turtle s shape is circle create cats 1 77 new turtle s shape is circle set default shape cats cat set default shape dogs dog create cats 1 7 new turtle s shape is cat ask cats set breed dogs all cats become dogs 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
58. random one of or boolean or boolean2 Reports true if either boolean or boolean2 or both is true Note that if condition is true then condition2 will not be run since it can t affect the result if pxcor gt 0 or pycor gt 0 set pcolor red 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 180 Primitives Dictionary NetLogo 2 0 2 User Manual 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 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 gre
59. 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 red 7 the left half of the screen turns red and 7 the right half turns blue show n values 10 ifelse value lt 5 0 1 gt 000001111 1 show reduc ifelse valu 21 22 11 2211 T3025 3 83 20 gt 8 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 t
60. 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 ist Ai 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 7 does the same thing as nsum var sum values from neighbors4 var 7 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 Primitives Dictionary 179 NetLogo 2 0 2 User Manual 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 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 one of agentset If given a turtle 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
61. show random 3 0 iP Prints 0 TL OE 2 show random 3 5 prints 0p 2 03 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 for example 1 0897423196760796 random exponential random gamma random normal random poisson random exponential mean random gamma alpha lambda random normal mean standard deviation random poisson mean Reports an accordingly distributed random number with the mean and in the case of the normal distribution the standard deviation random exponential reports an exponentially distributed random floating point number random gamma reports a gamma distributed random floating point number as controlled by the floating point alpha and lambda parameters Both inputs must be greater than zero Note for results with a given mean and variance use inputs as follows alpha mean mean variance lambda 1 variance mean random normal reports a normally distributed random floating point number 188 Primitives Dictionary Ne
62. 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 e The on off switch lets you temporarily freeze the display The model keeps running but the contents of the graphics window don t change until you unfreeze it by flipping the switch again Most models run much faster when the graphics window is frozen Here are the settings for the Graphics Window accessible by editing the Graphics Window or by pressing the More button in the control strip 00 Editing Graphics Screen Edge X 17 Screen Edge Y 17 Patch Size pixels 9 0 Font Size of turtle and patch labels 10 Y Turtle Shapes Y Exact Turtle Positions amp Sizes Cancel Apply Co To change the size of the Graphics Window adjust the Patch Size setting which is measured in pixels This does not change the number of patches only how large the patches appear on the screen 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 var
63. sort a list according to a sort order define myself 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 convert an agentset to a list or vice versa e How does NetLogo decide when to switch from agent to agent when running code General What language is 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 ps 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 web 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 informati
64. the main interface e The only values the sliders can take are those that they actually had in the experiment Behavior plot Displays the data from individual runs as you move the mouse over their corresponding squares on the fitness landscape It s x axis is time clicks and its y axis is behavior that is the value reported by the behavior reporter entered in the setup window e The best fit line or curve can be added along with the data if the add best fit line checkbox is selected e Run data can be continually collected in the plot and superimposed on each other by selecting the superimpose plots checkbox e Only 14 plot pen colors are used so if more than 14 data sets are superimposed at a single time the system will begin reusing colors for the new pens e Automatically scales to show all data Add best fit line checkbox Adds the line or exponential curve that best fits the data to the behavior plot depending on whether linear or exponential was selected in the slope type menu Superimpose plots checkbox Stops old data from being removed from the behavior plot when new data is added resulting in increasing sets of data being superimposed on each other Unselected the checkbox causes all data to be removed Export Plot button Saves the data currently being displayed in the behavior plot to a file Export Behavior Data button Saves the behavior data gathered during all of the model runs to a file The data s
65. the model Can you see any other factors or variables that might affect the male to female ratio within each group Make predictions and test your ideas within this model Feel free to manipulate more than one variable at a time Sample Model Party 21 NetLogo 2 0 2 User Manual 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 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
66. the range 0 360 not 90 270 as they previously did fixed bug where numbers in sliders displayed in scientific notation could be shown with an incorrect exponent 4 fixed minor issue where remove primitive evaluated its arguments right to left instead of left to right e computer HubNet improvements computer HubNet is no longer alpha or beta but a normal release improved reliability greatly improved graphics window mirroring features and performance this is now no longer considered an experimental feature improved activity Tragedy of the Commons now out of unverified new unverified activities Polling Advanced Gridlock Alternate Beer Game Beer Game Alternate 1 Beer Game Alternate 2 server now asks for a name for the computer that is running the activity this can be the facilitator s name or some other name it is displayed on the clients in the server menu server menu on clients now only lists servers that are running a compatible version of NetLogo and the version is also checked when connecting you can now export data from a plot in a client by right or control clicking new feature text input widgets in clients enables clients to input text or NetLogo code into the simulation Version 1 3 1 September 2003 10 e system on Mac OS X systems running Java 1 4 1 Update 1 don t give spurious warning that the wrong version of Java is installed e documentation fixed some broken links in the
67. use hubnet send user name list Graphics Window Graphics Window 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 It should be mentioned that if there is no Graphics Window in the clients or if the Mirror Graphics Window on Clients checkbox in the HubNet Control Center is not checked then no graphics updates are sent to the clients NOTE Since Computer HubNet is still in the process of being developed the way that graphics updates take place including the syntax of sending the NetLogo Graphics Window using the hubnet broadcast and hubnet send primitives may change in a future release Plot Updates on the Clients Plots on the clients are updated in the following way If a change occurs on a NetLogo plot 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 HubNet Authoring Guide 109 NetLogo 2 0 2 User Manual 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 p
68. 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 BehaviorSpace Guide 89 NetLogo 2 0 2 User Manual configurations will yield the kind of behavior you are interested in This amounts to the question of where in its huge multi dimension parameter space does your model perform best For example suppose you want speedy synchronization from the agents in the Fireflies model The model has four sliders number cycle length flash length and number flashes that have approximately 2000 100 10 and 3 possible values respectively That means there are 2000 100 10 3 600 000 possible combinations of slider values Trying combinations one at a time is hardly an efficient way to learn which one will evoke the speediest synchronization BehaviorSpace offers you a much better way to solve this problem If you specify a subset of values from the ranges of each slider it will run the model with each possible combination of those values and during each model run record the results In doing so it samples the model s parameter space not exhaustively but enough so that you will be able to see relationships form between different sliders and the behavior of the system After all the runs are over a dat
69. 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 of blue cars The stream of cars are all moving in the same direction Every so often they pile up and stop moving This is modeling how traffic jams can form without any cause such as an accident a broken bridge or an overturned truck No centralized cause is needed for a traffic jam to form You may alter the settings and observe a few runs to get a full understanding of the model As you are using the Traffic Basic model have you noticed any additions you would like to make to the model Looking at the Traffic Basic model you may notice the environment is fairly simple a black background with a white street and number of blue cars and one red car Changes that could be made to the model include changing the color and shape of the cars adding a house or street light creating a stop light or even creating another lane of traffic Some of these suggested changes are cosmetic and would enhance the look of the model while the others are more behavioral We will be focusing more on the simpler or cosmetic changes throughout most of this tutorial
70. your network supports the server discovery feature you may instead choose the activity from the list shown Regardless of how you choose the Computer HubNet server you will also have to enter a User Name Please enter one The leader will give directions on how to choose one If no one else is using the one you enter NetLogo will send you the client interface and you can start playing If you didn t choose a unique User Name your client application will display a message indicating this 98 HubNet Guide NetLogo 2 0 2 User Manual You should keep trying new User Names until you are able to enter A good method for choosing a unique User Name is to use your first and last name together For example if your name is Joe Smith you might want to choose the User Name joesmith HubNet Control Center One feature of Computer HubNet is the HubNet Control Center You can open this using the HubNet Control Center option in the Tools Menu when a Computer HubNet Activity is open and the server is running The Control Center shows you useful information such as the IP address of the computer who is logged in etc It also allows you to disconnect clients from the activity and send out instructions or messages for all the clients to read In addition to these features the HubNet Control Center allows you to control whether debugging output is on or off Debugging output is useful when creating your own HubNet activity or to keep track of which part
71. 1 1t 45 fd 1 7 each turtle creates one new turtle 7 and the child turns and moves away 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 7 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 5 if turtle was showing it hides and if it was hiding 162 Primitives Dictionary NetLogo 2 0 2 User Manual 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 Removes points drawn by the current plot pen then draws a histogram of the values reported when all agents in the agentset run the given reporter It 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 p
72. 7 FIUIDNERACIVITIGS 2s suis ance aeee ue nao randy ada us La ia SRS A A EE Saad 97 Running an activity A 97 HubNet Authoring Guide ad 99 Computer HubNet Troubleshooting TipS cccoonoooccccccconoconononncnnonnnccnonanononnnnncccnannnnnoncnnnnnnns 99 Known Computer HUBNGEISSUGS acia 101 Known bugs all SYStemM5 occocccccccnnccnnccnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnninnnnss 101 HubNet Authoring Quide ii nenna nnmnnn ennan nnmnnn nnmnnn nnmnnn nnmnnn 103 General HubNet Information eee err tener tacar caras tan 103 NetLogo Primitives eae eeae rena rre 103 A casera taecaachoimectedshs tate A AE 103 Data Oxia CON sist sive ata A el Ae eee Fe dieses ae Bie leat 104 SOMO Cala fi E cai ee CG RUE cen Eat aba 105 EXIM PISS cacas qi DSR dd Sd dad DR O 106 Calculator HubNet Information retrata nono nano na naco non nana na nnnnannns 106 A OS 107 Computer HubNet Information ira adi s e 107 How To Make an Interface for a Cli8Nt ooocccccccncccncccnoconononoconononanacononanacanonanananonanananos 107 Graphics Window Updates on the ClientS ccccconnnooooccccnnnncccnonnanonnnnnncncnnnannnnncnnnnnnnns 109 Plot Updates on the Clients ida 109 Clicking in the Graphics Window on ClientS ccccconnnonooccncnnnnccnnnnnnononnnccccnnnnnnnnnnnnnnnnnns 110 Text Area for Input and DiSplaY ccccccccnnnoonccccnnonccononannnononnncccnnnnnnnnnnnnncnnnnnnnnnnnnnnnnnnnns 110 Net
73. 9 9999 The chart shows that e Some of the colors have names You can use these names in your code e Every named color except black and white has a number ending in 5 e On either side of each named color are darker and lighter shades of the color e 0 10 20 and so on are all black 9 9999 19 9999 29 9999 and so on are all white 70 Programming Guide NetLogo 2 0 2 User Manual Code Example The color chart was made in NetLogo with the Color Chart Example model 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 is available and you can either decrease the brightness darken or decrease the saturation lighten of those hues to get your desired color but you may not decrease both the brightness and saturation There are a few pr
74. A O AO IA DA Ra BP DAS CANA ERC REISS LOSER EE DA ROC ROT DO CA A 155 filg at end A A ate dene 155 IE A sda Doca tn Us ah ad SG oh Aa ns Bn N eg a A 155 Tile close al acata ie rea Poe ds Ses JRR 156 file del te E Bek Sec card dad E de ga SER Ca ra SR dea s dE a SG E EEE 156 TILE 0XISIS 2 5 O E SUS SRA Da REA A 156 SOPA es IES con DS DAE taa 156 MOS A A RR A 157 IEA A A U A E E PORO 157 file read CharacierS ui ia 158 OS AAN it A Seen A taal ale 158 THO AO a dad ed Dee tle 158 A O cman taeda ton 159 Oo WO nD A E E T Soa TA ab OLA had 159 Ma A nae Aira RE SEEN iS 159 TESTA Fe tratar ea dra ceded vane da et ral DA dh tee arg es ba dn a ah ci shied 160 TOO hers nenem her tire AA Bre Ad Ro A RA AD da o E a a a A AS 160 LOIRET e aE E A ER RR 160 forward isa A AAN RT E 161 A Ge hs 03 Bacto Ded ceed wba de E a EE 161 Eos Rand e el aes o toa E a AO A oa 161 Get date and timMe san o A conde 161 globals k aves diaria ara Dad O US teases Dairies eed dev bea eana di ad 161 aa ana et aceite Ts Mate tenet RN 162 Matei 2a 4d RA A EEEE Sd e eae SA ANA A A IIA 162 Nai caida naaa adas ida 162 faito e E1 a E ba IA AA anaes seas 162 A sts Bet ee atte as pices sae det teat etek 8 Moet dae Mase lia als pias ate Gp Sabie Dene ato De 163 STO ae OMT Us PNR AMEI Ed UR E O RUDE A PETS E ERR 163 NetLogo 2 0 2 User Manual Table of Contents Primitives Dictionary histograMalStiicitana aaa 163 A A ON 164 SD e os A RR A A e A A RO O
75. AGE REDE a Ea Da daN o 145 Clear Paiches Coscia notn nii ia bai 146 ClO Al DlO bee OSS AA EE a DRE ER PISAR PERDE evel eS 146 cear mies Cl a caso eee A a US ut CEC Ma ale E Sd ce da 146 COIOR ce rss mi te a AU Aes aaa PE as eta da Ned ED dado ae Ae 146 COS saio a e ARA EE 147 COUNT cust IRS AU TR PR DRE ND RB DR RAND RS NT DIC ONDE Sanayi S 147 create lturiles crt creatle lt BREEDA errante nana 147 create custom turtles cct create custom lt BREED gt cct lt BREED gt 147 create temporary plot pen eee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeegeeeeeeeeeeeeeeeeeeeseeeeeeeees 148 Di o dis ct a SE aide es aa Ps ed E et ca a ad Gaede da paca dd Oe SR 148 e 1 E A E DE E A di E DE SRA ENA 148 MA e neg a de EEE O 149 NetLogo 2 0 2 User Manual Table of Contents Primitives Dictionary vi o N O Koy A Ai ta A RR 149 A RR 149 CUS TANG Reet A A A a A A A Rd 150 distance NoWraD aiii iia 150 OISTANCO Vitis A A A nadie 150 CUSTANCOX Y NOW AD ii idas 151 GOW MMI sc eet aa Tita co sae 151 o LON AALA TIl L APEE Pe a rr ia isa 152 dX dY arpe NC RT DR e NS E CI RIR IR E E ER RE 152 RS 152 O 152 MA en ne 152 OVEN A ein ied RO RP DOR 153 O 153 export graphics export interface export output export plot export all plots OXDOM WONG iia ae 153 EXC SD A A a RA NO DE RN A 154 Si GD ws tesyzccvdases era ieee headaches dass rent tea Pagan Ra dette cbc bent caga died real ad eg ahaa 155 Esad REE IC
76. E Programs grant numbers REC 9814682 and REC 0126227 For random number generation NetLogo uses the MersenneTwisterFast class by Sean Luke The copyright for that code is as follows Copyright c 2003 by Sean Luke Portions copyright c 1993 by Michael Lecuyer All rights reserved Redistribution and use in source and binary forms with or without modification are permitted provided that the following conditions are met e Redistributions of source code must retain the above copyright notice this list of conditions and the following disclaimer e Redistributions in binary form must reproduce the above copyright notice this list of conditions and the following disclaimer in the documentation and or other materials provided with the distribution e Neither the name of the copyright owners their employers nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS AND ANY EXPRESS OR IMPLIED WARRANTIES INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED IN NO EVENT SHALL THE COPYRIGHT OWNERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT INDIRECT INCIDENTAL SPECIAL EXEMPLARY OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES LOSS OF USE DATA OR PR
77. Java 1 3 or higher e new primitives run runresult map foreach filter reduce sort by self asin acos e some primitives such as 1 ist now accept a variable number of inputs e many improvements to usability and reliability of computer HubNet Version 1 2 March 2003 e models run faster now e beta level support for running as a native application on Mac OS X e running the full authoring environment as an applet in a web browser is no longer supported saving individual models as applets is still supported however 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 many new primitives and other language improvements e display of coordinates when mousing over plots Version 1 1 July 2002 e models run faster now e Save as Applet lets you embed your model in any web page e printer support e Procedures menu e scrollable Interface tab e contextual menus in Interface tab e improved agent monitors e experimental Turtle Sizes and Exact Turtle Positions options What s New 11 NetLogo 2 0 2 User Manual e many new primitives e improved HubNet support improved activities Version 1 0 April 2002 e initial release after a series of betas 12 What s New System Requirements NetLogo is designed to run on almost any type of computer but some older or less powerful systems ar
78. Logo 2 0 2 User Manual Table of Contents EXTENSIONS E e EA e nen EE E E E E A 111 Using Extension S dea a a a a a a a a e E a aa e d 111 Applets e a e E Eae aee ae a ae PINA r aae Ooa eia ashes 112 Writing Extensions c ccscceeeeeseeeseeeeeeeeeeeeeeeaeeeeeeeeeeeaeeaeeeaeeeeseeeseaeeaeaeeeaeeeaeeeseenseesseeseeeees 112 SUI a cas 112 TUlO loci a a a a a cs 112 Extension development tipS cocccccccccccnnncnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnninnniss 115 CONCIUSION Last das a rd ARCA EN ID E E da EE Da SOS dl dianas 116 Controlling UI O ciao 117 AQUEX Olarte ae eA ARRE A aa 117 COTS OTIS At a cucu Tedeanene a 118 GONGCIUSION E nn NERD REDE ARA PROERD RR a 118 NeiLogo Sound Extensi dd 119 USING the SOUNGE NISMS ON A AA AA RR da Ga lous 119 PrIMIIVES Sas esa ethos Pos Leda Dig le hl E E E o R e Sata Ea E AS 119 O LU La o FARA ARA ORA NERD DE vg doves ee DSR RS DE OD SN RDNS MS 119 INSIFUMENTS siso ede i wine disease a eles Maine Sheed shuld Yt retin iu Mate hub thee 119 PIV SOU a HS ANPR RA EEE EES E rusts aah PIERRE RDNS REPETIR ES AS SEER 120 PV DO ii GU RPA RR E RODE DR RN RR RSS RI 120 STAN OB ita ai NA RR A RR eae a 120 1e o EE OIEA E O 120 SOSA eE A EEEE EEE E A E A E 121 SOPAS Clean 121 SOUNA NAMOS ia A da tao 121 A La pia iodo san cena ca a Slate a ange tyatiuettas A 121 Instruments 4 cena ca sev A ae A E io a E eed E E O DR o Cn 2 121 FAQ Frequently Asked QuUestiONS coc
79. Net Activity got a dialog that said Could not start the Computer HubNet server Another program may be using the port that is needed Another program perhaps another copy of NetLogo is using a port or some other resource that HubNet needs Check to see if you have another copy of NetLogo open that is running Computer HubNet If you do quit it and then try reopening the model If you don t you can try quitting other HubNet Guide 99 NetLogo 2 0 2 User Manual programs and reopening the model until you are able to start the Computer HubNet server successfully Somehow two or more HubNet Clients are controlling the same agents in the simulation and they aren t supposed to What can do to fix this problem Remove all of the clients from the simulation by either by having the people exit the activity or by using the Kick Client feature in the HubNet Control Center to forcibly remove them If you wish them to still be in the simulation they all should log back in with different user names had run and then stopped a HubNet model changed windows or minimized NetLogo or did something else to obscure or redraw the Graphics Window When came back to the NetLogo the Graphics Window was all gray What happened Is all my data lost Most likely what has happened is that the Graphics Window is not longer being updated because the no display primitive was called or the freeze unfreeze display button in the Graphics Window Control Str
80. NetLogo 2 0 2 User Manual 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 et broadcast A 3 14 et send Jimmy A 3 14 et broadcast STR1 et sends TIZ TIS SiR HERE I HERE t send t broadcast L2 t message source L2 t broadcast t send suzy 3 4 1 et broadcast hubnet send teacher user names jimmy user names Jjimmy 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 calculator sends and receives data by storing a set of parameters in the string St ro Depending upon what type of data you are trying to send or receive St ro will have different values For instance if the modeler wanted to create and send a list
81. OFITS 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 provided that the above copyright Copyright Information 3 NetLogo 2 0 2 User Manual 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 4 Copyright Information What s New Feedback from users is very valuable to us in designing and im
82. T and NetLogo The original StarLogo was developed at the MIT Media Lab in 1989 1990 and ran on a massively parallel supercomputer called the Connection Machine A few years later 1994 a simulated parallel version was developed for the Macintosh computer That version eventually became MacStarLogo StarLogoT 1997 developed at the Center for Connected Learning and Computer Based Modeling CCL is essentially an extended version of MacStarLogo with many additional features and capabilities Since then two multi platform Java based multi agent Logos have been developed NetLogo from the CCL and a Java based version of StarLogo from MIT The NetLogo language and environment differ in many respects from MIT StarLogo s Both languages were inspired by the original StarLogo but were redesigned in different ways NetLogo s design was driven by the need to revise and expand the language so it is easier to use and more powerful and by the need to support the HubNet architecture NetLogo also incorporates almost all of the extended functionality of our earlier StarLogoT You can use the chart below to help familiarize yourself with the new features NetLogo has to offer StarLogoT NetLogo Features O O O E Fully programmable Powerful and flexible plotting system E ane Agent Monitors for inspecting agents x Cross platform runs on MacOS Windows Linux etal X_ Models can be saved as applets to be embedded inawebpage FAQ
83. 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 observer Refer to the Interface Guide for details explaining the different parts of the Command Center Tutorial 2 Commands 33 NetLogo 2 0 2 User Manual In Traffic Basic e Press the setup button e Locate the Command Center e Click the mouse in the white box at the bottom of the Command Center e Type the text shown here Command Center Clear O gt ask patches set pcolor yellow e Press the return key What happened to the Graphics Window You may have noticed the background of the Graphics Window 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 a
84. WINDOW 323 339 638 108 HubNet Authoring Guide NetLogo 2 0 2 User Manual 459 Command Center For more examples study the models and interface files in the HubNet Computer Activities section of the Models Library Disease nlogo and Disease client nlogo are good ones to start with Graphics Window Updates on the Clients Currently there are two ways of sending the clients the Graphics Window The first way is done automatically by NetLogo and HubNet when Graphics Window mirroring is enabled Whenever a patch or turtle is redrawn in the NetLogo Graphics Window it will be redrawn on all the clients 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 using the no display and display primitives A second way of sending the clients the Graphics Window is to use the hubnet broadcast and hubnet send primitives hubnet broadcast and hubnet send both send the entire Graphics Window to the clients instead of just the patches that need to be redrawn This makes them less efficient but sometimes better for a particular model To send the Graphics Window to the clients using this scheme you must use the following NetLogo code hubnet broadcast Graphics Window Graphics Window to send to all the logged in clients To just send the Graphics Window to a subset of all the clients
85. a from multiple runs of a model Export and import functions export data save and restore state of model 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 specific prior permission must be obtained from Uri Wilensky The software models and documentation shall not be used rewritten or adapted as the basis of a commercial software or hardware product without first obtaining appropriate licenses from Uri Wilensky We make no representations about the suitability of this software for any purpose It is provided as is without express or implied warranty To reference this software in academic publications please use Wilensky U 1999 NetLogo http ccl northwestern edu netlogo Center for Connected Learning and Computer Based Modeling Northwestern University Evanston IL The project gratefully acknowledges the support of the National Science Foundation REPP and ROL
86. able 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 See also no label label plabel plabel color Example ask turtles set label color red all the turtles now have red labels last last list last string On a list reports the last item in the list On a string reports a one character string containing only the last character of the original string Primitives Dictionary 171 NetLogo 2 0 2 User Manual 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 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 75 or similar list show list 5 gt 5 show list random 10 1 2 3 random 10 gt 4 1 2 3 9 7 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 Locals is a keyword used to declare local variables in a procedure that is variables that are usable only with
87. activities Tragedy of the Commons bugfix Gridlock Alternate bugfix improvements Sampler bugfix server discovery is now off by default in the client since we suspected it of causing problems on some configurations fixed bug where the list of servers contained duplicates fixed assorted bugs with plots displaying incorrectly fixed bugs that caused the clients graphics to sometimes be out of sync with the server 6 What s New NetLogo 2 0 2 User Manual Version 2 0 0 December 10 2003 e system NetLogo now requires Java 1 4 1 or higher on non Macintosh systems 1 4 2 is preferred NetLogo now fully supports Mac OS X not beta anymore Mac OS X 10 2 users are strongly encouraged to get Java 1 4 1 Update 1 through Software Update NetLogo no longer supports Windows 95 MacOS 8 or MacOS 9 however we will continue to support NetLogo 1 3 x which works on those systems our user interface now uses Java s Swing toolkit and not the older AWT toolkit increased overall reliability NetLogo now functions more smoothly in many respects on Linux and probably other Unix systems our recommended Java VM on Windows is now Sun 1 4 2 instead of IBM 1 1 8 we offer an installer that includes this VM e content new biology models Fur Sunflower new physics model Turbulence new chemistry model B Z Reaction new computer science models CA Continuous CA Stochastic new social science model Gridlock non Hu
88. 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 E fa 1 1 7 only the turtles on the patches at the 7 distances 2 4 1 2 and 10 15 relative to the caller mov 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 is on for the current plot false otherwise 142 Primitives Dictionary
89. ample Here is a small but complete program that starts NetLogo opens a model moves a slider and runs the model for a few seconds import org nlogo app App import org nlogo compiler CompilerException import java awt EventQueue public class Example public static void main String argv App main argv try Event Queue invokeAndWait new Runnable public void run App app open models Sample Models Earth Science Fire nlogo 13 App app command set density 62 App app command setup for int i 0 i In order to compile and run this NetLogo 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 Controlling Guide 117 NetLogo 2 0 2 User Manual 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 Other Options When your program controls NetLogo using the App class the entir
90. an t be entirely certain of this we do not know if the problem is specific to Linux or can occur on Solaris and other Unixes as well NetLogo users are encouraged to visit http developer java sun com developer bugParade bugs 5023712 html registration required and vote for Sun to fix this bug Known Issues 15 NetLogo 2 0 2 User Manual Known issues with computer HubNet See the_HubNet Guide for a list of known issues with computer HubNet Planned features This is only a partial list of features we plan to add Periodically new versions of NetLogo will be available from our web site e Export World and Import World save and restore the contents of plots too e Declaring constants in the procedures tab e Models detect and react to individual keystrokes e Let command for introducing a new local variable anywhere in the code e Add arrays as a distinct data type from lists e Optional randomized agent scheduler e Ability to have multiple models open e Making a QuickTime movie of your model e Parenthesis and bracket matching in the editor Unimplemented StarLogoT primitives The following StarLogoT primitives are not available in NetLogo Note that many StarLogoT primitives such as count turtles with are intentionally not included in this list because NetLogo allows for the same functionality with the new agentset syntax e maxint minint maxnum minnum e beep e readlist e import turtles import patches import tu
91. ape is not the fitness of the run but the value of the chosen statistic For instance the minimum value of the run is shown when minimum value is selected in the point statistic type menu This value is not necessarily the fitness of the run however since the goodness of a particular value changes when you make a new selection in the point statistic value menu e The grid has a maximum height and width which is reached when there are more than 5 squares in either direction and cannot be resized e Squares turn gray when there is insufficient information to construct a grid this happens when either axis has not been assigned a slider one axis is sufficient if a model only has one slider Set of sliders components held constant These sliders consist of all those not present as axes of the fitness landscape Since all the model runs represented on the landscape have the same value for these sliders namely the one currently selected on the slider components they are considered held constant for the landscape By changing the value of a single one of these sliders BehaviorSpace Guide 93 NetLogo 2 0 2 User Manual the whole landscape changes because it now represents a whole new set of runs If you changed a slider from 10 to 12 say then all the runs in which that slider had the value 10 are replaced by those in which it had the value 12 e Changing the value of these sliders does not affect the value of the sliders on
92. appened 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 Note in addition to sliders and switches some models have a third kind of setting called a choice 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 graph 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
93. are that this causes the restriction that you can only have one interface element with a specific name Having more than one interface element with the same Display Name in the client interface will cause funny things to happen 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 Be aware that if you wish to have a Graphics Window in the client for a model the Graphics Window 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 Graphics Window on the client will not display information sent by the server If you wish to make a client without a Graphics Window 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 in a 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 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 CHSHCHS HE CC
94. ariable 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 Primitives Dictionary 215 NetLogo 2 0 2 User Manual 2 21 22 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 1 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 216 Primitives Dictionary
95. aset is generated which you can open in a different tool such as a spreadsheet or scientific visualization application and explore The idea behind BehaviorSpace is that the way to truly understand a model is to run it multiple times with different parameter slider settings in order to see the whole range of behaviors the system is capable of producing Only then is it possible to investigate when and why certain behaviors arise Isolated trials are insufficient for this purpose because you have no reason to assume that the model will always demonstrate the particular behaviors you see It s like eating in one restaurant in New York and then claiming you ve seen all that the city has to offer By enabling you to explore the entire parameter space of a model and thus its entire space of behaviors BehaviorSpace can be a powerful tool for model understanding How It Works To begin using BehaviorSpace open your model then choose the BehaviorSpace item on NetLogo s Tools menu A small window will appear containing Edit Experiment Setup and Run Experiment buttons Press Edit Experiment Setup to begin setting up your experiment Setting up an experiment In the dialog that appears you ll need to specify the following information Vary variables as follows This is where you specify which settings you want varied and what values you want them to take Settings can be sliders switches choices or any global variable in your model You ma
96. atches 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 can use On other operating systems the ceiling is determined by your Java VM Here s how to raise the limit if you need to e Windows Edit this section of the NetLogo lax file in the NetLogo folder LAX NL JAVA OPTION JAVA HEAP SIZE MAX allow the heap to get huge lax nl java option java heap size max 536870912 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 VMOptions lt key gt lt string gt XX PrintJavaStackAtFatalState Xms16M Xmx512M lt string gt 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
97. ated with the keyboard dialog boxes support cut copy and paste using keyboard shortcuts the command center and the Procedures and Errors tabs now use the exact same syntax highlighting editor resolving many small issues and inconsistencies in behavior added a Go to User Community Models web page button to the Models Library dialog fixed longstanding Windows bug where the output area of the command center could only hold 25K there is now no known limit the graphics window and plots are flicker free now plots containing very large numbers of points are faster now you can now press the Enter or Return key to close dialog boxes when turtle shapes are off if the patch size is at least 5 then turtles are now drawn slightly smaller than the patches so if a turtle is in the center of its patch you can still see the patch color around its edges agent monitors now report syntax errors to you instead of silently ignoring them graphics control strip icons have tooltips now improved the automatic sizing and positioning of the main NetLogo window so that available screen real estate is more fully utilized changed the keyboard shortcuts for zooming indenting and commenting to more standard choices fixed bug where if you made changes to your code in the Errors tab and then saved your model without switching tabs first your changes wouldn t be saved e language changes changes in random number generation N
98. aved for each model run includes the slider settings for that run how many time ticks the run lasted the minimum maximum average and final value for the behavior reporter and the value of the behavior reporter at each time tick during the run Note that the fitnesses are not exported only the raw behavior data In a future version of BehaviorSpace the fitness data will be exported as well Note The export buttons create files in plain text comma separated values csv format CSV files can be read by most popular spreadsheet and database programs as well as any text editor gt 94 BehaviorSpace Guide HubNet Guide 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 TI 83 calculator or a networked computer 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 calculator or computer For more information on participatory simulations and their learning potential please visit the Participatory Simulations Project web site e About HubNet HubNet Types What do need to get started 4 Calcu
99. b 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 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 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 ca
100. bNet version new ProbLab model Random Basic new code examples One Turtle Per Patch Example Look Ahead Example Grouping Turtles Example User Interaction Example Neighborhoods Example Partners Example Random Seed Example models improved Plant Growth bugfix Fireflies interface changes Decay made flashing optional Fire new turtle based version is much faster Percolation much faster Ants bugfix Rugby bugfix improved code Segregation bugfix improved code models improved and promoted out of unverified Sand bugfix Wandering Letters overhauled Lattice Gas Automaton Dining Philosophers Turing Machine 2D Division CA Continuous CA Stochastic Vector Fields Random Basic Prob Graphs Basic Stochastic Patchwork new sections in Programming Guide on Random Numbers Buttons and Math restored missing punctuation marks in PDF version of User Manual e features the Exact Turtle Positions and Turtle Sizes settings have been merged into a single option and they are now much faster more reliable and flicker free so much so in fact that they are now on by default turtle and patch labels are much faster now too a full of suite of primitives for reading and writing external files is now included see the File I O section of the Programming Guide in the User Manual for details strict math mode is now always on so model results are reproducible cross platform new Export Graphics a
101. bar 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 lowest elevations are and where they can be found a o 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 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 50 Tutorial 3 Procedures NetLogo 2 0 2 User Manual end But now we
102. because i 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 pseudorandom 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 sequence of random numbers from then on For example if you run these commands random seed 137 show random 100 show random 100 show random 100 You will always get the numbers 95 7 and 54 Code Example Random Seed Example 82 Programming Guide NetLogo 2 0 2 User Manual 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 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
103. 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 e Press setup to get the red car to reappear e If you are on a Macintosh hold down the Control key and click on the red car On other operating systems click on the red car with the right mouse button e From the popup menu that appears choose inspect turtle 0 A turtle monitor for that car will appear 38 Tutorial 2 Commands NetLogo 2 0 2 User Manual Taking a closer look at this turtle monitor we can see all of the variables that belong to the red car A variable is a place that holds a value that can be changed Remember when it was mentioned that all colors are represented in the computer as numbers The same is true for the agents For example 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
104. changes when opened in the new version 0 dropped support for pc as an alias for pcolor 0 renamed any to any and user yes or no lo user yes or no 0 renamed histogram to histogram from 0 dropped support for set plot pen as an alias for create temporary plot pen e engine fixes fixed bug where using report or stop inside a repeat or foreach loop could cause incorrect results or a Java exception What s New 9 NetLogo 2 0 2 User Manual fixed bug where some primitives including value from of distance towards and inspect did not deal properly with dead turtles fixed bug where every didn t work as expected when used inside an explicit without interruption 4 fixed issue where using without interruption always caused an agent s turn to end after the code inside ran fixed bug where under certain very obscure circumstances dead turtles could continue to execute code for a short time after dying fixed obscure bug where if a turtle agentset was stored in a variable and in a turtle in the set died then under certain circumstances code that subsequently tried to use the agentset could cause a Java exception fixed bug where using hat ch with a negative number could cause a Java exception now it just does nothing fixed bug where min and max didn t signal a runtime error in every case if given an list with no numbers in it fixed towards and towards nowrap towardsxy and towardsxy nowrap to return numbers in
105. 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 example extension manifest txt Extension Name exampl Class Manager SampleExtension etLogo Version 2 0 2 114 Extensions Guide NetLogo 2 0 2 User Manual 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 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 Comma
106. cncncccnononnonnnonnnnnonnnnnnnnnnnnnnronnnnnnnnnnrerrnnnnnnnnnnnnnnnss 28 The Models LibralV asin aene a rae aaae sd 31 sample Models niusi a eri n a na a 32 Gurricuilar Models EASE A oda Gece adn eet EN E E A 32 Gode EXAMINAR 32 HubNet Calculator 8 Computer ActIV tIOS ccooooooocccncccccononononncncccnnnnnannnncncnnnnnnnnnnnnnnnos 32 VA ARTE AM NOX ai A A AR E A SR RR 32 Tutorial f2 ComimandS ssa sas a EEE sciatica E da eed eee aie ee et anal la ee 33 Sample Model Traffic Basica ASSADA ae ba LA ama 33 The Command Genter viii di A inane wee 33 NV orking Nin GOLOS ams sara Sb A E T tne leateseaeane tes 36 Agent Monitors and Agent COMIMANUEeIS cooooocccccnccccnonononononcncccnnnnnnnonnnnncnnnnnnnnnnrnnrnnnnrnnnnnnnnnss 38 AAT dias TESA cP eee eo AE EE S ds tal ARS pedal A 41 Tutorial 3 e AS 43 SONATA DO dia one tea RENT SR A a ias 43 Patches and Varnables bodas he 47 An Uphill Algorithm taa 50 Some More DetaiS ss ad ties a e a E E E 54 AAEE N ENAA E E EE E E AA E re E A 55 Appendix Complete Code presin a a La 56 Interface GUIDE r ssa aa e a a FRA daa aida 59 O es TCO a RNID pi do A NNR sa A O a 59 MAIN WINDOW zi os 61 Interiace Tab a A eet ace T 61 Procedures Tai iS ibd iene tee di Sa SE 64 Information Taba sta cok A Sevageeuscioasseuees 65 Errors a e DE 66 Programming GUIAS A at ae ented 67 PACING Ae A NGO E E AE QU OA O Rd O E 67 PrOCOQUIeS Aa Sted ee et AS ST SD 68 Nadal RR PoE A A A AAA A A 69 UM o ie ca
107. ctions e If you are on a wireless network or sub LAN the IP address in the HubNet Control Center is not always the entire IP address of the server e Authoring new HubNet activities is more arcane and difficult than it should be e Computer HubNet has only been tested on LANs and never via dial up connections or WANs e Sometimes servers displayed in the list of servers in the HubNet client may be repeated When this occurs it doesn t matter which one you choose HubNet Guide 101 NetLogo 2 0 2 User Manual 102 HubNet Guide HubNet Authoring Guide This explains how to use NetLogo to modify the existing HubNet activities 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 Graphics Window Updates on the Clients Plot Updates on the Clients 4 Clicking in the Graphics Window 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 In the model the modeler uses a set of commands to set the model up to use a type of HubNet extract data from and send data to the Navigator system or the computer clients Below you can find explanations of each of the NetLogo primitives
108. d 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 EE AA eoo iaaa O Agent s Observer HJ Display Name setup o Code Forever Y Force display update after each run Checking this box causes smoother screen updates but may make the button run more slowly 4 Press OK to dismiss the dialog box 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 Tutorial 3 Procedures 43 NetLogo 2 0 2 User Manual At this point both the new button and the Errors tab have turned red That s because there is no procedure called setup If you want to see the actual error message switch to the Errors tab interface Information Procedures Errors fee 5 FR i abc Button Slider 13 Switch Em Choice 25 Monitor 1 gt qi More 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 easi
109. d usa atrai aida ie a CA CU UU a wee 181 DAC Nat a6 AN DR RR RR RO ERROR asus ORA O RS RR EEN ARE PEER 181 patch at heading and distance erre ear arara ease ease eeaaeesanesaeeano 182 Patch a at isa ve Ds aa A A A da a 182 patch left and ahead patch right and ahlead cccccccononococononcconannonnnnnnnnnnnnnnnananonnnnos 182 PalcheS Sat da Catv E EURO TRENS VE A aa 183 PATCHES Ma 183 PalCheS OWA iteitscc tita na ici A A eee 183 DCOIOM ti A A ard wea waited anaes 183 pen down pd pen up Pl ee 184 PENSO aid ienes terror R a a a 184 9 1 o 5 PRAENEOPROS SONORO DRE ORDENS GESTAO AA 184 plabel COlOL assuste as oa a e Rd sides du aaa 184 A snc ae O A e E A cetera as een 185 PIO NAME snsc Abi 185 plot pen down ppd plot pen up PU ccccccnccnccnncnnnnnnnnnnnnnnnnnnnnnnnnnnnnennnnrnnrnnnrrnnr ranas 185 plot pen resel saias AAA A A Cte aed 185 10 61 PVA E NO 185 plot x min plot x max plot y Min plot y max essere 186 POSI A AA Ad 186 POCO A O Aa 186 E SE S 187 PXCOl DY CO iii E 187 A A ita da Ea 187 MAA a o at dado lis Ra IS 187 ca ae AS alas Ld Gide a wate O SELO DANA AA DE aa T DU S aaa 188 NetLogo 2 0 2 User Manual Table of Contents Primitives Dictionary random exponential random gamma random normal random poisson 188 FANGOM i O TO Ate a same eras Grab ta bi 189 random n 0L asas A i A A Ae e A ONG Se 189 A dan 190 random sSeCA ias a A N tn 190 TOA MOM ASIN e
110. d 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 NetLogo s Models Library Primitives drums instruments play drum play note start note stop n
111. da a SRS 206 A 207 TUNES TOM ii A E acne 207 turtles here BREED here errar nan cnn nacen cananea 207 turtles 0n BREE Dns ioc da es chee ie lite 208 turtles own BREED QOWDO coonccccnccccncononncoconcnnonncononannonannonnnano narran nnnnn narra narran rea arena 208 WM A 209 6 JRR ONE ADRs NO E SEEE A x Sea cere Mg ele ge cbc sate Ra ane RAND 0 SRS NR 209 TP RR RR DEU RU RE RR nits aari 209 CEA as seh Ara a O NS E DR AE AE 209 WAE EEE ei 210 USEr ChOOSE dIFECION iaa 210 DIa oeae eae nsec E E E AE N E E E E 210 US r ChHOOSE NEW FiIO cc ccecececceeeeceeceeeeeeeseeeuceseceeeseceesuenseeeeseuseeeeeensceeesaneaseseauaaeeasenes 210 USEF input ida 211 USE MOSS AN licua 211 USERS O NO asd nad EE rain pe GEE enar e eee aA EAEE A ea eui ass 211 A ae mR SoD TB A ARA 211 VALE OM a RR RR 211 VOEO AAE E iS A A AA A ees 212 Ve it ds 212 Minas E OA actA sd 212 Md e a E La Lada 212 Wisin cows abuts 212 WO NNE TETEE EEr TET es ds Cia cdas 213 WINE Ret A eos a DO MA AS IB SS ON Aa A 213 wiihout interrupPllON cionado lidad dal 213 WO ia A RE A eae ie AI AS 214 Wrap Colo amada raised 214 MI ro 214 NetLogo 2 0 2 User Manual Table of Contents Primitives Dictionary xi NetLogo 2 0 2 User Manual xii 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 instr
112. de NetLogo allows users to write new commands and reporters in Java and use them in their models This section of the User Manual introduces this facility The first part discusses how to use an extension in your model once you have written one or once someone has given you one The second part is intended for Java programmers interested in writing their own extensions 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 extensio
113. 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 can be read into NetLogo On the other hand writing allows data to flow out of NetLogo and into a file When working with files always begin by using the primitive 1 1e open This specifies which file you will be interacting with None of the other primitives work unless you open a file first The next file primitive you use dictates which mode the file will be in until the file is closed reading or writing To switch modes close and then reopen the file The reading primitives include file read file read line file read characters and file at end Note that the file must exist already before you can open it for reading 84 Programming Guide NetLogo 2 0 2 User Manual 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 When you are finished using a file you can use the command file close to end your session with the file If you wish to remove the fil
114. di 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 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 e random and turtles are primitive reporters random takes a single number as an input and reports a random integer that is less than the input in this case between 0 and 9 turtles reports the agentset consisting of all the turtles We ll explain about agentsets later 68 Programming Guide NetLogo 2 0 2 User Manual setup and go can be called by other procedures or by buttons Many NetLogo models have a once button that calls a procedure called set up 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 Variables Variables are places to store values such as numbers
115. diately became visible So NetLogo waits until a certain amount of time has passed usually about 1 20 of a second and then redraws the world 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 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 the user 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 screen 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 d
116. display box temporarily stores all of the commands that are entered into the Command Center This area is strictly for reference commands cannot be accessed or changed from this box To clear this box click clear in the top right corner 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 64 Interface Guide NetLogo 2 0 2 User Manual Interface Information Procedures Errors al a 4 Compile Y Find Y Find Again Compil
117. e 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 procedure 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 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 elevation variable to that number Tutorial 43 Procedures 47 NetLogo 2 0 2 User Manual 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
118. e globals ticks breeds sheep wolves turtles own energy sheep own grabbed used to prevent two wolves from eating the sc patches own countdown Procedures w to setup ca set ticks O 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 clc if random 2 O half the patches start out with grass set pcolor brown To determine if the code has any errors press the Compile button If there are any syntax errors the Errors tab will come to the front of the screen and turn red 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 compiled and any errors will be shown so if you switch tabs pressing the Compile button first isn t necessary To find a fragment of code in the procedures click on the magnifying glass on the Procedures Toolbar Then enter the text you are looking for and hit the Find button The Find Again button finds the next location of the word or fragment of code throughout the procedure 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 Shif
119. e 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 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 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 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 turtle s breed like this if breed wolves 74 Programming Guide NetLogo 2 0 2 User Manual 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
120. e other BREED here patch ahead patch here patch left and ahead patch right and ahead pen down pd pen up pu right rt self set default shape setxy showturtle st sprout stamp 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 inspect is patch myself neighbors neighbors4 no label nobody 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 value from Agentset primitives any ask at points BREED at BREED here BREED on count histogram from in radius min one of neighbors neighbors4 one of other turiles here other BREED here patches patches from random n of random one df turtles with turtles at turtles from turtles here turtles on values from Color primitives extract hsb extract rgb hsb rgb scale color shade of wrap color Primitives Dictionary 137 NetLogo 2 0 2 User Manual Control flow and logic primitives and end foreach if ifelse ifelse value locals loop map not or repeat report run runresult semicolon stop startup to to report wait while without interruption xor Display primitives clear all ca clear graphics cg clear patches
121. e 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 Programming Guide 69 NetLogo 2 0 2 User Manual 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 7 turtle with ID number 5 turns red set pcolor of patch 2 3 green 77 patch with pxcor of 2 and pycor of 3 turns green ask turtles set pcolor of patch at 1 0 blue every turtle turns the patch to its east blue ask patches with any turtles here set color of random one of turtles here yellow 7 on every patch a random turtle turns yellow Colors 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 9999 gray 5 8 9 9 9999 red 15 MA 19 19 9999 orange 25 28 29 29 9999 brown 35 38 39 39 9999 yellow 45 48 49 49 9999 green 55 58 59 59 9999 lime 65 T68 69 69 9999 turquoise 75 78 79 79 9999 cyan 85 8 amp 8 89 89 9999 sky 95 98 99 99 9999 blue 105 100 02 108 109 109 9999 violet 115 110 3 118 119 119 9999 magenta 125 120 12 22 3 128 129 129 9999 pink 135 130 13 33 138 139 13
122. e E SE E AT 70 AS A o a ado a Oe Rie e O ans at e ae a a A ana ani 71 Agentsets ui iii 73 Breeds A a 74 DUO e ESATEN EIEE pos ASA E EEEE EE ti ada oa ora de a ta da ala VEE qa a a Lai aaa dao 75 Synchronization eae den eiia a tases dase s exam te STE NAAA Macedntuadciuaania de 77 Procequres advance aid 77 MS A AS EN ATA mnie ots 78 Mall Es a a a in e de e de las Bi ere tat a 81 Random NUM A E AEE 82 NetLogo 2 0 2 User Manual Table of Contents Programming Guide SIMI ado 83 TUS SADO ido id e SUE eSEE ATI 84 ool 521 FAG Sudia rasas aon Bee a A UR IC EE do OD A CSO a 84 Shapes Editor Guide a 87 CAB TEL INCEST A SS GE eae vie ulna tawny 87 Creating and Editing ShApes ccccccononocoonccnccononanonnncnnonnnnnnnnnnnnnnnnnnnrcnnnnnnnnnnnnnnccnnnnnnnnnnnnnnnnn 87 Using Shapes ina Mod crisis aaa E E E A 88 BehaviorSspace Guide pras li ates ress A A te eee oes 89 BehaviorSpace Old and NOW cccccccccsssssesensceceeeeeessscneceeeeeeeeseeeeeneeeeeeeeeeessseensaeeeeeeeeneees 89 Whatis Behavior pace ada aii da 89 HOWE WOTKS toria A eae A ld eee ec cee et ee 90 Setting Upa EXPONEN a Ea 90 NS A 91 Conclusion is 92 Hubb Net Gide coccion dde dida ld ci 95 About HlubNet ens ea o me AF A e A DA A PAE A D O e 95 HubNet Types esse eri id 95 What do ne edie g t started iia a 96 First time NetLogo USERS A A a 96 Teacher workshops nn nnrrmnnnnns 96 Getting Started With HUB 97 USING NOIA CAES eU eins eae eee a 9
123. e 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 We are also working on making it possible to run NetLogo headless that is with no GUI at all but at present this is not possible 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 118 Controlling Guide NetLogo Sound Extension The NetLogo Sound Extension provides primitives to add sound to NetLogo models The extension simulates a 128 key electronic keyboard with 47 drums an
124. e Stick 61 Low Bongo 38 Acoustic Snare 62 Mute Hi Conga 39 Hand Clap 63 Open Hi Conga 40 Electric Snare 64 Low Conga 41 Low Floor Tom 65 Hi Timbale 42 Closed Hi Hat 66 Low Timbale 43 Hi Floor Tom 67 Hi Agogo 44 Pedal Hi Hat 68 Low Agogo 45 Low Tom 69 Cabasa 47 Open Hi Hat 70 Maracas 47 Low Mid Tom 71 Short Whistle 48 Hi Mid Tom 72 Long Whistle 49 Crash Cymbal 1 73 Short Guiro 50 Hi Tom 74 Long Guiro 51 Ride Cymbal 1 75 Claves 52 Chinese Cymbal 76 Hi Wood Block 53 Ride Bell 77 Low Wood Block 54 Tambourine 78 Mute Cuica 55 Splash Cymbal 79 Open Cuica 56 Cowbell 80 Mute Triangle 57 Crash Cymbal 2 81 Open Triangle 58 Vibraslap Instruments Piano Reed 1 Acoustic Grand Piano 65 Soprano Sax 2 Bright Acoustic Piano 66 Alto Sax 3 Electric Grand Piano 67 Tenor Sax 4 Honky tonk Piano 68 Baritone Sax 5 Electric Piano 1 69 Oboe 6 Electric Piano 2 70 English Horn 7 Harpsichord 71 Bassoon 8 Clavi 72 Clarinet NetLogo Sound Extension 121 Chromatic Percussion 9 Celesta LO Glockenspiel L1 usic Box 12 Vibraphone 13 Marimba L4 Xylophone L5 Tubular Bells L6 Dulcimer Organ 17 Drawbar Organ 18 Percussive Organ 9 Rock Organ 20 Church Organ 21 Reed Organ 22 Accordion 23 Harmonica 24 Tango Accordion Guitar 25 Nylon String Guitar 26 Steel Acoustic Guitar 27 Jazz Electric Guitar 28 Clean Electric Guitar 29 Muted Electric Guita
125. e afterwards use the primitive i le delete to delete it To close multiple opened files one needs to first select the file by using i1e open before closing it 7 Open 3 files file open myfilel txt file open myfile2 txt file open myfile3 txt Now close the 3 files file close file open myfile2 txt file close file open myfilel txt file close Or if you know you just want to close every file you can use file close all Two primitives worth noting are file write and file read These primitives are designed to easily save and retrieve NetLogo constants such as numbers lists booleans and strings file write will always output the variable in such a manner that file read will be able to interpret it correctly file open myfile txt Opening file for writing ask turtles file write xcor file write ycor file close file open myfile txt Opening file for reading ask turtles setxy file read file read file close Letting the user choose It should be noted also that 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 Programming Guide 85 86 NetLogo 2 0 2 User Manual Programming Guide Shapes Editor Guide The Shapes Editor allows you to create and save turtle designs NetLogo uses fully scalable and rotatable vector graphics which means it lets you create designs
126. e colors It contains only certain discrete hues and for each hue either saturation or brightness may vary but not both at least one of the two is always 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 enter message hubnet enter message Reports true if a new computer client just entered the simulation Reports false otherwise hubnet message source will contain the user name of the client that just logged on See the_HubNet Authoring Guide for details and instructions hubnet exit message 164 Primitives Dictionary NetLogo 2 0 2 User Manual hubnet exit message Reports true if a computer client just exited the simulation Reports false otherwise hubnet message source will contain the user name of the client that just logged off See the_HubNet Authoring Guide for details and instructions hubnet fetch message hubnet fetch message If there is any new data sent by the clients this retrieves the next piece of data so that it can be accessed by hubnet message hubnet message source and hubnet message tag This will cause an error if
127. e 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 instead We plan to continue to support NetLogo 1 3 Mac OS X e OS X version 10 2 6 or later e 128 MB RAM 256 MB RAM 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 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 instead We plan to continue to support NetLogo 1 3 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 preferr
128. e 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 be 25 or so Then change your code to repeat smoothness diffuse elevation 1 Experiment with the turtles performance in different terrains 52 Tutorial 3 Procedures NetLogo 2 0 2 User Manual 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 ta
129. e range of the histogram fixed minor bug where exported world files sometimes contained a incorrectly formatted timestamp e interface fixes shift clicking to close an agent monitor now closes all open agent monitors you can now put blank lines in a text box and they will survive being saved and loaded errors in procedures defined first are now reported first improved appearance of models library dialog on Windows 4 fixed 2 x only bug where Net LogoLite jar was not double clickable fixed bug in BehaviorSpace where if you only specified one value for a variable e g foo 3 that value was ignored 4 fixed Mac only bug where control clicking a button would trigger it as well as opening the contextual menu e computer HubNet changes fixed bug that could cause a Java exception in some circumstances e extensions API changes new convenience classes DefaultReporter and DefaultCommand ClassManager methods now throw ExtensionException What s New 5 NetLogo 2 0 2 User Manual Version 2 0 1 May 7 2004 e system our bundled Java VM on Windows is now Sun 1 4 2_04 was 1 4 2_02 e features new experimental extensions API lets users write new commands and reporters in Java see new Extensions section of User Manual previously unpublished controlling API lets users control NetLogo from external Java code such as for automating multiple runs see new Controlling section of User Manual e content
130. e user to enable the activity 7 AAA Gridlock 1 3 and looks for the calculator j lists Ll and LOCS on the Navigator server hubnet set client interfac COMPUTER clients Disease client nlogo 7 when clients log in they will will get the interface described in the file clients Disease client nlogo relative to 7 the location of the model Future versions of HubNet may support other client types and or change the meaning of the second input to this command 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 turtles on the right half of the screen 7 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 The reporter may report a different value for different agents so some agents may run commands1 while others run commands2 Primitives Dictionary 167 NetLogo 2 0 2 User Manual 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
131. ead of always using 100 turtles you can have a variable number of turtles Make a slider variable say number A e AA f Editing Slider Global Variable Ram Minimum 0 Increment 1 Maximum 99 Value 55 Units optional d 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 54 Tutorial 3 Procedures NetLogo 2 0 2 User Manual globals highest 7 maximum patch elevation lowest 7 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 pai 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 What s Next So now you have a nice framework for exploring this problem of hill climbing u
132. ean 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 black 0 white 9 9999 gray 5 8 9 9 9999 red 15 18 19 19 9999 orange 25 28 29 29 9999 brown 35 38 39 39 9999 yellow 45 48 49 49 9999 green 55 58 59 59 9999 lime 65 68 69 69 9999 turquoise 75 78 79 79 9999 cyan 85 88 89 89 9999 sky 95 i os 99 99 9999 blue 105 100 108 109 109 9999 violet 115 110 111 118 119 119 9999 magenta 125 120 121 128 129 129 9999 pink 135 130 131 138 139 139 9999 Tutorial 2 Commands 37 NetLogo 2 0 2 User Manual 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 eType set pcolor red 2 By adding to red you make it lighter You can use this technique on any of the colors listed in the chart Agent Monitors and Agent Commanders In the previous activity we used the set command to
133. ed If you have trouble please contact us see above 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 System Requirements 13 NetLogo 2 0 2 User Manual 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 14 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 gracefully e The run and runresult primitives do not work properly if their input contains any uses of the special variables 21 22 etc e The stop command does not work properly if used inside without interruption 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
134. ee 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 user Also the file cannot be open Use the command file close to close an opened file before deletion Note that the string can either be a file name or an absolute file path If it is a file name it looks in whatever the current directory is This can be changed using the command set current directory It is defaulted to the model s directory file exists file exists string Reports true if string is the name of an existing file on the system Otherwise it reports false Note that the string can either be a file name or an absolute file path If it is a file name it looks in whatever the current directory is This can be changed using the command set current directory It defaults to to the model s directory file 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 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 fi
135. eed 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 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 turtles 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 last On strings but first and but last report a shorter string omitting the first or last character of the Original string 7 mylist is 2 4 6 5 8 12 set mylist but first mylist 7 mylist is now 4 6 5 8 12 set mylist but last mylist 7 mylist is now 4 6 8 show but first string 144 Primitives Dictionary NetLogo 2 0 2 User Manual 77 prints tring show but last string 7 prints strin C 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 Kills all turt
136. en 7 turns the patch 1 in front of the calling turtle ao green note that this might be the same patch ve 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 5 if Caller is the observer turn the patch Hee at 1 1 green 7 if Caller is a turtle or patch turns the Primitives Dictionary 181 NetLogo 2 0 2 User Manual a patch just southeast of the caller green See also patch patch ahead patch left and ahead patch right and ahead patch at heading and distance patch at heading and distance patch at heading and distance heading distance k 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 A 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 No
137. en 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 7 draws a histogram showing how many turtles there are 77 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 Removes points drawn by the current plot pen then draws a histogram of the values in the given list See histogram from above for more information Primitives Dictionary 163 NetLogo 2 0 2 User Manual home home Moves the turtle to the origin 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 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 possibl
138. eporter lt takes an input list and another reporter Note that unlike foreach the reporter comes first like this show map round 1 2 2 2 2 7 7 prints 1 2 3 map reports a list containing the results of applying the reporter to each item in the input list Again use to refer to the current item in the list 80 Programming Guide NetLogo 2 0 2 User Manual 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 1 and 2 are used in place of Here is an example of sort by show sort by 1 lt 2 4 1 3 2 pp 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 in
139. er for others to read as well Interface Information Procedures Errors E Find 2 Find Again o 2 Compile Procedures w to setup ca crt 100 ask turtles fd random screen edge x 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 initialize any variables you might have to 0 and remove all turtles 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 fd random screen edge x is a command that also uses reporters Reporters as o
140. er versions of NetLogo these primitives were used in many situations where the new patch ahead primitive is now more appropriate E empty empty list empty string Reports true if the given list or string is empty false otherwise Note the empty list is written The empty string is written end end Used to conclude a procedure See to and to report 152 Primitives Dictionary NetLogo 2 0 2 User Manual 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 the same ask or button press or command typed in the Command Center So it doesn t make sense to write ask turtles every 0 5 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 se
141. ers or even on the same computer since the model may run at a different speed Such models are rare these two commands are common but using them in a way that affects the outcome is not e In order to reproduce model runs exactly you must be using the exact same version of NetLogo The details of the agent scheduling mechanism and the random number generator may change between NetLogo versions and other changes bugfixes in the engine language changes and so forth may also affect the behavior of your model Then again they may not e We have expended every effort to make NetLogo model runs fully reproducible but of course this can never truly be an iron 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 128 FAQ Frequently Asked Questions NetLogo 2 0 2 User Manual 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 present no If this is a problem for you contact us at feedback ccl northwestern edu downloaded and installed NetLogo but the Models Library has few or no models in it How can
142. etLogo now uses the research grade Mersenne Twister algorithm to generate all random events 0 added new random gamma primitive for generating gamma distributed random numbers 0 added new random float primitive that always returns a floating point number changed randon primitive so it always returns an integer not a floating point number What s New NetLogo 2 0 2 User Manual 0 added new random int or float primitive that behaves the way random used to when opening an old NetLogo 1 x model all uses of random will automatically be changed to random int or float but we suggest you edit the model and change every occurrence to either random or random float as appropriate 4 atan O 0 is now a runtime error and so is using towards and towardsxy and so on to ask for the heading from a point to that same point we now support unary minus if you put parentheses around it so for example you can now write x added new n values reporter for conveniently constructing lists by repeatedly running a reporter added new reporters patch ahead patch right and ahead patch left and ahead and patch at heading and distance helpful for giving turtles vision among other uses added new shuffle reporter for shuffling a list added new modes reporter for finding the most frequently appearing items in a list added new remove item primitive for removing an item from a list or string at a specified position added new turtles
143. fe helper methods such 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 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 DefaultClassManager import org nlogo api PrimitiveManager 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
144. format that has your model embedded in itas a Java applet ends the contents of the currently showing tab to your printer xport World Saves all variables and the current state of all turtles and patches to a file Export Plot Saves the data in a plot to a file Export All Plots Saves the data in all the plots to a file Export Graphics Save a picture of the graphics window to a file in PNG format O pen odels Librar lt 9 ep rint m Save Interface Guide 59 NetLogo 2 0 2 User Manual xport Output Save the contents of the output section of the command center to a file mport World Load a file that was saved by Export World Exits NetLogo On Macs this item is on the NetLogo menu instead Cuts out or removes the selected text and temporarily saves it to the lipboard Copies the selected text aste Places the clipboard text where cursor is currently located elete Deletes selected text Undo last text editing action you performed Finds a word or sequence of characters within the Information Procedures or Errors tab ind Again Find the next occurrence of the word or sequence you last used Find with Shift Right ode Uncomment ode semicolons are used in NetLogo code to indicate comments Stops all running code including buttons and the command center Warning since the code is interrupted in the middle of whatever it was doing you may get unexpected results if you try to continue run
145. groups for example party games or school like activities But in a non structured atmosphere people tend to group in a more random manner Is there any type of pattern to this kind of grouping Let s take a closer look at this question by using the computer to model human behavior at a party NetLogo s Party model looks specifically at the question of grouping by gender at parties why do groups tend to form that are mostly men or mostly women Let s use NetLogo to explore this question What to do 1 Start NetLogo 2 Choose Models Library from the File menu NetLogo 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 19 NetLogo 2 0 2 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 Graphics Window 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 a
146. gt 1352 4 123 4 5 12 3 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 k This is a built in turtle variable It holds a number that is the turtle s apparent size in the graphics window The default size for a turtle 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 All turtles appear the same size in the graphics window unless the Turtle Sizes checkbox in the graphics window edit dialog is checked If that checkbox is not checked you can still use this variable but it will not have any visible effect Note the Turtle Sizes feature is currently considered experimental It may cause your model to run much more slowly and it may cause display anomalies 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 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 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 202 Primitives Dictionary NetLogo 2 0 2 Use
147. h a future release version of Tl Navigator Computer HubNet e A networked computer with NetLogo installed and optionally an attached projector for the leader This computer will run NetLogo and act as the server for the HubNet Clients The projector if attached will project the simulation for class viewing NOTE By default the NetLogo Graphics Window and plots are not mirrored to the HubNet clients For instructions on how to make a HubNet model mirror the NetLogo Graphics Window or plots to clients please refer to the Computer HubNet portion of the Running an activity section e A networked computer with NetLogo installed for each participant Be aware that Computer HubNet has only been tested on LANs and never via dial up connections or WANS It performance is unknown using these types of networks First time NetLogo user 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 if you choose 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 h
148. he file you wish to import See export world for an example 168 Primitives Dictionary NetLogo 2 0 2 User Manual in radius in radius nowrap agentset in radius number agentset in radius nowrap number 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 7 each turtle makes a red splotch around itself inspect inspect agent Opens an agent monitor for the given agent turtle or patch inspect patch 2 4 an agent monitor opens for that patch inspect random one of sheep 77 an agent monitor opens for a random turtle from 7 the sheep breed 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 is patch agentset Primitives Dictionary 169 NetLogo 2 0 2 User Manual 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
149. iable 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 choice e A variable belonging to the calling agent e If the calling agent is a turtle a variable belonging to the patch under the turtle e An expression of the form VARIABLE of agent set current directory set current directory string Sets the current directory that is used by the primitives file delete file exists and file open The current directory is not used if the above commands are given an absolute file path This is defaulted to the user s home directory for new models and is changed to the model s directory when a model is opened Note that in Windows file paths the backslash needs to be escaped within a string by using another backslash CN The change is temporary and is not saved with the model Note in applets this command has no effect since applets are only allowed to read files from the same directory on the server where the model is stored set current directory C NetLogo Assume it is a Windows Machine file open myfile txt 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
150. iables The Turtle Shapes checkbox performs the same function as the shapes button in the control strip discussed above In most NetLogo models turtles are visible at their exact locations and may vary in size If you turn off the Exact Turtle Positions checkbox then e Every turtle is drawn at the same size e Every turtle is drawn as if it were standing on the center of its patch Interface Guide 63 NetLogo 2 0 2 User Manual e Only the top turtle on a patch is visible This makes a model appear is it would have in earlier versions of NetLogo which did not support turtle sizes and exact turtle positions This checkbox does not change behavior of a model only its visual appearance 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 Cleai T gt set color red P gt set pcolor white O gt ask turtle 10 set color blue O gt ask turtle 1 set color blue o gt crt 10 You will notice there is a large display box an agent popup menu O gt a clear button and the history popup menu with the little black triangle The top large
151. ial 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 Procedures with local variables A local variables is defined and used only in the context of a particular procedure To add a local variable to your procedure use the locals keyword It must come at the beginning of your procedure For example to swap colors turtlel turtle2 locals temp set temp color of turtlel set color of turtlel color of turtle2 set color of turtle2 temp end 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 The Primitives Dictionary has a section that lists of all the list related primitives Constant Lists You ca
152. ible to the user only their final state Primitives Dictionary 149 NetLogo 2 0 2 User Manual 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 display 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 7 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 display update takes place once the agent is done running without interruption Note that display and no display operate independently of the switch in the graphics window control strip that freezes the display See also no display distance distance 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 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 now
153. icipant sent what data when Any output is sent to the log txt file on Windows machines or the Console to Macs The Control Center also allows you to control whether the NetLogo Graphics Window and plots are mirrored on the clients These options are useful if there are a lot of changes to the Graphics Window or plots or if you just don t wish the clients to see what is happening on the clients By default these options are turned off since they are not suited for all models HubNet Authoring Guide If you wish to learn more about authoring or modifying HubNet activities you should look at the HubNet Authoring Guide Computer HubNet Troubleshooting Tips Here are some things that have been known to go wrong and ways of fixing or working around them have tried quitting a HubNet Client but it just sits there and won t quit no matter how many times I try You will have to force the client to quit On Macs force quit the application Command Option Esc On Windows open the Windows Task Manager Ctrl Alt Delete select Hubnet and press End Task Then you should inform the leader of the simulation to use the HubNet Control Center to kick your client out of the simulation We believe that we have resolved all instances of these problems with the exception of the client trying to quit when it has lost its network connection If you encounter this problem and still have a network connection please let us know When open a Computer Hub
154. icult to develop an intuition about what reduce does here are some simple examples which while not useful in themselves may give you a better understanding of this primitive show reduce 1 2 1 2 3 gt 6 show reduce 1 22 1 2 3 gt 4 show reduce 2 21 1 2 3 gt 2 show reduce 1 1 2 3 gt sd show reduce 2 1 2 3 gt 3 show reduc sentence 1 2 1 2 3 4 5 gt 1 2 3 4 5 show reduce fput 2 1 fput 1 2 3 4 5 gt 5 43 2 1 Here are some more useful examples find the longest string in a list to report longest string strings report reduce ifelse valu length 1 gt length 2 1 2 strings end Primitives Dictionary 191 NetLogo 2 0 2 User Manual 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 number show remainder 62 5
155. ils and examples The_values from primitive lets you construct a list from an agentset It reports a list containing the 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 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 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 Programming Guide 79 NetLogo 2 0 2 User Manual set mylist lput 42 mylist mylist is now 2 7 10 Bob 3 0 2 42 But what if you changed your
156. imitives 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 shade of orange 27 is true because 27 is 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 zgb 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 t
157. in that procedure It must appear at the beginning of the procedure before any commands A local variable may not have the same name as an existing observer turtle or patch variable See to and_to report 172 Primitives Dictionary NetLogo 2 0 2 User Manual to hunt turtle procedure locals prey set prey random one of other turtles her if prey nobody eat prey end log log number base Reports the logarithm of number in base base show log 64 2 gt 6 See also In 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 user can click the button to stop the loop Iput Iput value list Adds value to the end of a list and reports the new list 7 suppose mylist is 2 7 10 Bob set mylist lput 42 mylist 7 mylist now is 2 7 10 Bob 42 map map reporter list map reporter list 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 Primitives Dictionary 173 NetLogo 2 0 2 User Manual gt 1 2 3 show map 1 2 3 gt 1 4 9 With multiple lists the
158. ion lowest turtles moved 7 minimum patch elevation 77 so we know when to stop the model 7 We also have two slider variables number and 7 smoothness number determines the number of 7 turtles and smoothness determines how erratic 5 terrain becomes during diffusion of elevation 7 resets everything 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 highest max set ask patches if elevation set pcolor if elevation set pcolor set pcolor scale color green elevation 1000 9000 values from patches elevation lowest min values from patches elevation gt highest 100 white lt lowest 100 black end 7 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 1f not turtles moved stop end 56 Tutorial 3 Procedures NetLogo 2 0 2 User Manual 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 fa 1 set turtles moved t
159. ional identifier to help make servers discovered on the client more different and unique If you don t wish to enter a name just press the Cancel button hubnet set client interface client type client info If client type is TI 83 client info is a list containing two items The first item is a string containing the name of the activity to enable on the TI Navigator web site hubnet set client interface TI 83 notifies the user to enable this activity The second item is a list of the tags for which to check The tag list sets which variables NetLogo expects from the calculators NetLogo will only check for these variables and will ignore all others Currently the valid types that NetLogo will be able to receive from the calculator are the following 0 Valid calculator lists such as L1 or PLOTS 0 Valid calculator matrices such as A or B 0 Valid calculator strings such as Str1 or Str5 O Numbers such as A or B 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 TI 83 AAA Gridlock 1 3 L1 LOCS 7 notifies the user to enable the activity AAA Gridlock 1 3 and looks for the 7 Calculator lists Ll and LOCS on the Navigator server hubnet set client interface COMPUTER clients Disease clien
160. ip is pressed Try using the display primitive in the NetLogo Command Center or toggling the freeze unfreeze display button My computer went to sleep while running a HubNet activity When woke the computer up got an error and HubNet wouldn t work anymore We have had reports that if a computer goes to sleep while running Computer HubNet either the HubNet Client or the server sometimes things do not work after the computer wakes up Please send us the error message along with the situation that caused it However we suggest that people keep their computers from sleeping while running an activity In my HubNet client see the same server displayed multiple times in the list of available servers Which one should pick These all refer to the same server Pick any of them to select that server The clients Graphics Windows are not mirroring the NetLogo Graphics Window properly What is the problem There are a few things that could be wrong e Be sure that the clients actually have a Graphics Window The clients won t mirror the model s Graphics Window if they don t have one themselves e Ensure that Graphics Window mirroring is on by verifying that the Graphics Mirroring mirroring option is checked in the HubNet Control Center e Make sure that the display is on in the model If the display isn t on the client Graphics Windows will not be updated e Verify that the size of the Graphics Window in the NetLogo model and the Gra
161. itially 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 plotxy Primitives Dictionary 185 NetLogo 2 0 2 User Manual 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 range Their default values are set from the plot Edit dialog position position item list position string1 string2 On a list reports the first position of item in list or false if it does not appear On strings reports the position of the first appearance string1 as a substring of string2 or false if it does not appear Note The positions are numbered beginning with 0 not with 1 7 suppose mylist is 2 7 4 7 Bob show position 7 mylist gt 1 show position 10 mylist gt false show position rin string gt 2 See also_member precision precision number places Reports number rounded to places decimal places If places is negative the rounding takes place to the left
162. king 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 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 36 Tutorial 2 Commands NetLogo 2 0 2 User Manual Command Center Clear T gt set color yellow ERROR You can t use COLOR ina patch context because COLOR is turtle only 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 m
163. l 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 5 turtle with id number 5 turns red ask turtle 5 set color red 7 another way to do the same thing turtles turtles Reports the agentset consisting of all turtles show count turtles 206 Primitives Dictionary NetLogo 2 0 2 User Manual 7 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 setxy 2 3 show count dogs at 2 3 gt 5
164. lator HubNet Computer HubNet First time NetLogo user Teacher workshops e Getting Started With HubNet How to use NetLogo About the activities Running an activity 4 Calculator HubNet Computer HubNet e HubNet Authoring Guide e Computer HubNet Troubleshooting Tips e Known Computer HubNet Issues About HubNet HubNet Types Currently there are two types of HubNet available One called Calculator HubNet was created in conjunction with Texas Instruments and makes use of the TI Navigator system This type of HubNet uses TI 83 graphing calculators as the clients the devices used to control a portion of a NetLogo model The second type of HubNet is Computer HubNet This is adapted from the calculator version and uses laptop or desktop networked computers as the clients In the future we hope to add more types of HubNet that support other types of clients such as PDA s Personal Digital Assistants HubNet Guide 95 NetLogo 2 0 2 User Manual What do I need to get started Calculator HubNet e A computer with an attached projector This computer will run NetLogo and project the simulation for class viewing e A classroom set of Tl 83 graphing calculators e Ti Navigator wireless calculator network NOTE TI Navigator recently became commercially available To learn more about the TI Navigator system visit Texas Instruments site However HubNet does not work with this version of TI Navigator it might only work wit
165. ld 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 A Text Box lets you create text labels in the Interface tab Graphics Window The Graphics Window initially appears as a large black square on the Interface tab This is the graphical world of NetLogo s turtles and patches Some NetLogo models let you interact with the turtles and patches with your mouse by clicking and dragging in the Graphics Window The Graphics Window provides an easy way to open a turtle monitor or patch monitor 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 Turtle and patch monitors can also be opened from the Tools menu or by using the inspect command 62 Interface Guide NetLogo 2 0 2 User Manual There are a number of settings associated with the Graphics Window There are two ways of changing the settings by using the control strip along the top edge of the Graphics Window or by editing the Graphics Window as described in the Working With Interface Elements section above Or pressing the More button in the control strip is an alternate and quicker way gt HON More The controls in the control strip work as follows e The three sets of black arrows let you change the
166. le in reading mode When opening a file in writing mode all new data will be appended to the end of the original file If there is no original file a new blank file will be created in its place 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 156 Primitives Dictionary NetLogo 2 0 2 User Manual 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 ca
167. lename 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 to an external file given by the string filename The result file can be read back into NetLogo with the import world primitive export plot export all plots and export world save files in in plain text comma separated values csv format CSV files can be read by most popular spreadsheet and database programs as well as any text editor If the file already exists it is overwritten If you wish to export to a file in a location other than the model s location you should include the full path to the file you wish to export Use the forward slash as the folder separator Note that the functionality of these primitives is also available directly from NetLogo s File menu export world fire csv 7 exports the state of the model to the file fire csv located in the NetLogo folder export plot Temperature c My Documents plot csv 7 exports the plot named 5 Temperature to the file plot csv located in 77 the C My Documents folder 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
168. les resets all global variables to zero and calls clear patches and clear all plots clear all plots clear all plots is Clears every plot in the model See clear plot for more information clear graphics cg clear graphics gt Kills all turtles and clears all patches Combines the effect of clear turtles and_clear patches clear output cc clear output ig Clears all text from the output portion of the Command Center Primitives Dictionary 145 NetLogo 2 0 2 User Manual clear patches cp clear patches io Clears the patches by resetting all patch variables to their default initial values including setting their color to black clear plot clear plot In the current plot only resets all plot pens deletes all temporary plot pens resets the plot to its default values for x range y range etc and resets all permanent plot pens to their default values The default values for the plot and for the permanent plot pens are set in the plot Edit dialog which is displayed when you edit the plot If there are no plot pens after deleting all temporary pens that is to say if there are no permanent plot pens a default plot pen will be created with the following initial settings e Pen down e Color black e Mode O line mode e Name default e Interval 1 0 See also clear all plots clear turtles ct clear turtles e Kills all turtles See also_die color color k This is a built
169. les to choose the same mate l 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 keep two turtles from occupying the same patch How to best accomplish this depends somewhat on the details of how your model works The following techniques may be helpful e A turtle can test whether there are other turtles on the patch it is standing on with any other turtles here e A turtle can test whether there are other turtles on the patch it is facing with any turtles on patch ahead 1 This checks the patch that the turtle would land on if it executed fd 1 Note however that if the turtle s heading isn t a multiple of 90 then fd 1 will not necessarily take the turtle to a new patch it might only move from one corner of a patch to the opposite corner of the same patch Sometimes code that looks like it should prevent two turtles from ever being on the same patch can fail because of unexpected interactions between the turtles as they all execute the code
170. lider 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 Within this tab you will find an explanation of the model suggestions on things to try and other information You may want to read the Information tab before running a model or you might want to just start experimenting then look at the Information tab later What would happen to the sheep population if there was more initial sheep and less initial wolves at the beginning of the simulation 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 26 Tutorial 1 Models NetLogo 2 0 2 User Manual What h
171. ll to file read will skip past both leading and trailing whitespace Note that strings need to have quotes around them Use the command file write to have quotes included Also note that the file open command must be called before this reporter can be used and there must be data remaining in the file Use the reporter_file at end to determine if you are at the end of the file 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 Primitives Dictionary 157 NetLogo 2 0 2 User Manual 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 7 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
172. lotting messages to be sent to the clients It should be mentioned that if there is no plot with the exact same name in the clients 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 Graphics Window on Clients If the Graphics Window is included in the client it is possible for the client to send locations in the Graphics Window to NetLogo by clicking in the client s Graphics Window The tag reported by hubnet message tag for client clicks is the same as what is needed to send the Graphics Window to a client the string Graphics Window 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 Graphics Window ask patches with pxcor round item 0 hubnet message and pycor round item 1 hubnet message set pcolor red 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 110 HubNet Authoring Guide Extensions Gui
173. m reverse substring word Mathematical primitives log max mean median min mod modes 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 sum tan variance 138 Primitives Dictionary NetLogo 2 0 2 User Manual 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 ppd 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 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 Keywords breeds end globals locals patches own to to report turtles own Constants Mathematical Constants e 2 718281828459045 pi 3 141592653589793 Boolean Constants false true Color Constants The allowable range of values for colors is 0 up to but not including 140 Each color ranges from black to white over a scale of ten Thus the color red goes from black 10 to dark red 11 to red 15 to light red 19 to white 19 9999 The scale is discon
174. m 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 andom seed 47823 how random 100 gt 57 show random 100 gt 91 lo K 190 Primitives Dictionary NetLogo 2 0 2 User Manual 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 value nobody Useful in conjunction with the_user input primitive for converting the user s input into usable form show read from string 3 read from string 5 gt 8 show length read from string 1 2 3 gt 3 crt read from string user input Make how many turtles 7 the number of turtles input by the user are created reduce reduce reporter list Reduces a list from left to right using reporter resulting in a single value This means for example that reduce 1 22 1 2 3 4 is equivalent to 1 2 3 4 If 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 diff
175. mation on the current NetLogo version the user is running On Macs his menu item is on the NetLogo menu instead ser Manual Opens this manual in a web browser o 0 Interface Guide NetLogo 2 0 2 User Manual Main Window At the top of NetLogo s main window are four tabs labeled Interface Information Procedures and Errors 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 Errors f Edit 3 Delete abe Button Stl Slider IE 1 1 a 5 7 Choice BS Monitor Plot Abe al g Text L 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 Graphics Window 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 5 aa nd Lae Es Supe SPA f Edic Delete Pac Button i Y Switch Choice BS Monitor I Plot E Text The buttons in the toolbar are described below Working With
176. mber show random int or float 3 7 prints 0 1 or 2 show random int or float 5 0 7 prints a number at least 0 0 but less than 5 0 for example 4 686596634174661 random n of 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 Primitives Dictionary 189 NetLogo 2 0 2 User Manual 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 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 rando
177. mice own cheese to setup ca create custom mice 50 set color white set cheese random 10 create custom frogs 50 set color green 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 the user presses 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 the user presses the button again to stop it If the user stops 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 featu
178. mind The but 1ast b1 for short reporter reports all the list items but the last set mylist but last mylist mylist is now 2 7 10 Bob 3 0 2 Suppose you want to get rid of item 0 the 2 at the beginning of the list set mylist but first mylist mylist is now 7 10 Bob 3 0 2 Suppose you wanted to change the third item that s nested inside item 3 from 2 to 9 The key is to realize that the name that can be used to call the nested list 3 0 2 is item 3 mylist Then the replace item reporter can be nested to change the list within a list The parentheses are added for clarity set mylist replace item 3 mylist replace item 2 item 3 mylist 9 mylist is now 7 10 Bob 3 O 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 i ext gt 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 foreach 1 2 3 ask turtles fd 5 turtles move forward 6 patches foreach true false true true ask turtles if fd 1 1 turtles move forward 3 patches map is similar to foreach but it is a r
179. n for use by any model put the extension file for example sound jar in the extensions directory inside the NetLogo directory Or you can just 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 111 NetLogo 2 0 2 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 Applet
180. n 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 51 The empty list is written by putting nothing between the brackets like this 78 Programming Guide NetLogo 2 0 2 User Manual Building Lists on the Fly If you want to make a list in which the values are determined by reporters as opposed to being a series of constants use the List reporter The 1i st reporter accepts two other reporters runs them and reports the results as a list If wanted a list to contain two random values might use the following code set random list list random 10 random 20 This will set random 1i st to a new list of two random integers each time it runs To make longer 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 1 2 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 deta
181. n 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 data 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 Tutorial 3 Procedures 53 NetLogo 2 0 2 User Manual Turtles at Peaks Pens 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 inst
182. nce NetLogo must send the data to the Navigator server in Calculator HubNet it is not currently possible to send data from NetLogo directly to only an individual calculator However once the server has the data any connected calculator can grab it This is done using the calculators communication facilities rather than through NetLogo 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 send list of strings tag name value hubnet send string tag name value When using Calculator HubNet this primitive acts in exactly 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 0 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 Note sending a message to a non existent client using hubnet send generates a hubnet exit message For both of these primitives when using Calculator HubNet value may be a number a string a list of numbers or a matrix a list of lists of numbers For Computer HubNet you may send any kind of HubNet Authoring Guide 105
183. nd Export Interface menu items and export graphics and export interface primitives let you save the contents of the graphics window or the whole interface tab to disk as a bitmap in PNG format also enabling the creation of movies of model runs 4 4 4 4 4 4 What s New 7 NetLogo 2 0 2 User Manual the old BehaviorSpace tool has been scrapped a replacement version still under development is included it does not yet have all the functionality of the old tool but is already useful and already has the following advantages over the old version 0 you can vary any global variables not just sliders but also switches and choices and any variable declared in the procedures tab and the values they range over can be any values not just numbers anymore you can enter arbitrary code for setup and go now you re not tied to using buttons that exist in your model 0 you can vary variables in any order you want rather than BehaviorSpace choosing the order for you you can collect any result type you want not just numbers anymore added new Update screen each iteration checkbox for forever buttons for controlling whether a screen update is forced each time through the button new primitive set current directory lets you set the folder that file operations take place in e user interface improvements improved look and feel throughout the application mouse scroll wheels now work models library dialog can be navig
184. nd 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 information 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 Extensions Guide 115 NetLogo 2 0 2 User Manual 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 extensi
185. nd blocks inside some commands such as cct and hat around them tch have an implied without interruption 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 136 FAQ Frequently Asked Questions Primitives Dictionary ABCDEFGHIJLMNOPRSTUVWXY Categories Turtle Patch Agentset _Color Control Logic Display HubNet Input Qutput Files List erg Mee Plotting Special Variables Keywords _Constants Categories of Primitives This is an approximate grouping Remember that a turile 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 forward fd hatch hideturtle ht home inspect is turtle jump left It myself no label nobody of other turtles her
186. nd invited 150 people You are wondering how people will gather together Suppose 10 groups form at the party How do you think they will group Instead of asking 150 of your closest friends to gather and randomly group let s have the computer simulate this situation for us What to do 1 Press the go button Pressing go again will stop the model manually 2 Observe the movement of people until the model stops 3 Watch the plots to see what s happening in another way Now how many people are in each group Originally you may have thought 150 people splitting into 10 groups would result in about 15 people in each group From the model we see that people did not divide up evenly into the 10 groups instead some groups became 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 20 Sample Model Party NetLogo 2 0 2 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
187. ndard 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 then write x All of the comparison operators also work on strings and the addition operator also functions as a string concatenation operator see example below 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 Primitives Dictionary 141 NetLogo 2 0 2 User Manual all turtles move forward one step ask patches set pcolor red all patches turn red ask turtle 4 rt 90 7 Only the turtle with id 4 turns right at points
188. new social science models Scatter El Farol Minority Game new earth science model Erosion new code examples Hex Cells Example Hex Turtles Example Patch Clusters Example improved models Koch Curve revamped Binomial Rabbits bugfix Ant Lines bugfix Shepherds better code Prob Graphs Basic simplified interface Random Basic usability improvements Random Balls bugfix minor updates to the User Manual e engine fixes fixed bug where recompiling the model undid the effects of set default shape 4 fixed the ile read command so it skips trailing whitespace which makes it more convenient to use in conjunction with fi le at end fixed bug where using the mouse primitives could freeze NetLogo under certain unusual circumstances code of the form lt breed gt in radius now runs much faster e interface fixes fixed bug where turtle monitors were sometimes blank fixed bug where unfreezing the display from the graphics control strip sometimes caused a graphics update even when the no display command was in effect fixed bug where saving the model would close files opened by file open fixed shapes editor bug where changes to shapes weren t always immediately visible in the graphics window fixed shapes editor bug where renaming a shape would cause the shape to be duplicated fixed Windows only bug where code sometimes disappeared from buttons containing multiple lines of code e computer HubNet changes improved
189. ng only the turtles on my patch or only the turtles on some other particular patch There s also turtles on so you can get the set of turtles standing on a given patch or set of patches or the set of turtles standing on the same patch as a given turtle or set of turtles Here are some more examples of how to make agentsets 7 all red turtles turtles with color red all red turtles on my patch turtles here with color red 7 patches on right side of screen patches with pxcor gt 0 all turtles less than 3 patches away turtles in radius 3 7 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 7 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
190. ning the model without first pressing setup to start the model run over lobals Monitor Displays the values of all global variables urtle Monitor Displays the values of all of the variables in a particular turtle You can can also edit the values of the turtle s variables and issue commands to the urtle You can also open a turtle monitor via the Graphics Window see the Graphics Window section below Displays the values of all of the variables in a particular patch You can can also edit the values of the patch s variables and issue commands to the patch You can also open a patch monitor via the Graphics Window see he Graphics Window section below hapes Editor Draw turtle shapes See the Shapes Editor Guide for more information BehaviorSpace Guide for more information HubNet Control Disabled if no HubNet activity is open See the_HubNet Guide for more information Find Q C MZ o O op T O T CIUlvIO O Ol 5 im D O 5 O E fa 2 3 Q O D 3 o E D gt aca Patch Monitor lus arger Increase the overall screen size of the model Useful on large monitors or hen using a projector in front of a group ormal Size Reset the screen size of the model to the normal size maller 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 Infor
191. ns 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 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 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 Tu
192. nt 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 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 elevatio
193. nt 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 Primitives Dictionary 195 NetLogo 2 0 2 User Manual 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 scale color scale color color number range1 range Reports a shade of color proportional to number If range1 is less than range2 then the larger the number the lighter the shade of color But if range2 is less than range7 the color scaling is inverted If number is less than 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 Graphics Window screen edge x and y are the half width and half height of the NetLogo world the distances from the origin to the edges screen size is the same as 2
194. nt 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 200 Primitives Dictionary NetLogo 2 0 2 User Manual shade of color color2 Reports true if both colors are shades of one another false otherwise show shade of blue red gt false show shade of blue blue 1 gt true show shade of gray white gt true shape shape 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 See also set default shape 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 showturtle st showturtle The turtle becomes visible again Note This command is equivalent to setting the turtle variable hidden to false See also hideturile shuffle shuffle list Reports a new list containing the same items as the input list but in randomized order Primitives Dictionary 201 NetLogo 2 0 2 User Manual show shuffle gt 5241 3 show shuffle
195. nter the name of a procedure that sets up the model typically setup But it is also possible to include other commands as well Step model with these commands This is where you enter the commands that will be run to advance to the model to the next step Typically this will be the name of a procedure such as go but you may include any commands you like Stop after this many steps This lets you set a maximum length for each run If you don t want to set any maximum but want the length of runs to be controlled by the next setting setting instead enter 0 Stop if this reporter becomes true This lets you do model runs of varying length ending each model 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 enter false here Running an experiment When you re done setting up your experiment press the OK button followed by the Run BehaviorSpace Guide 91 NetLogo 2 0 2 User Manual Experiment button A window will appear titled Running Experiment In this window you ll see a progress report of how many runs have been completed so far and how much time has passed If the reporter you entered for Measure runs using this reporter reports a number then you ll see a plot of how that number varies over the course of each run You can watch your model r
196. nts 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 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 Primitives Dictionary 213 NetLogo 2 0 2 User Manual 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 7 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 b 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 itself If it is not wrap color wraps the numeric input to the O to 140 range The wrapping is done by repeatedly adding or subtracting 140 from the given number until it i
197. o api DefaultCommand DefaultReporter requires that we implement Object report Argument args Context context throws ExtensionException Since our reporter takes an argument we also implement Syntax getSyntax Here s the implementation of our reporter in a file called IntegerList java import org nlogo agent LogoList import org nlogo api Argument import org nlogo api ExtensionException import org nlogo api DefaultReporter import org nlogo api Syntax public class IntegerList extends DefaultReporter this reporter takes a number as an argument and returns a list public Syntax getSyntax return Syntax reporterSyntax new int Syntax TYPE_NUMBER Syntax TYPE_LIST public 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 throw org nlogo api ExtensionException to signal a NetLogo runtime error to the modeler throw new ExtensionException input must be positive populate the list for int i 1 i lt n i list add new Integer 1 return list Extensions Guide 113 NetLogo 2 0 2 User Manual Notice e To access arguments use org nlogo api Argument s typesa
198. o run that activity Click the Next gt gt gt button to advance to the next instruction HubNet Guide 97 NetLogo 2 0 2 User Manual We suggest doing a few practice runs of the activity before trying it in front of an actual class If you have any questions about running the activities feel free to E mail us You can reach us at feedback ccl northwestern edu Calculator HubNet When you open the first Calculator HubNet activity for each session of NetLogo you will be prompted by the TI Navigator Login dialog This prompts you to enter information such as User Id or Password that is necessary for connecting to the TI Navigator system and running the HubNet activity If you don t actually want to run the model just press the Cancel button For more information about how to log in to the calculators and other details of using Calculator HubNet please refer to the Participatory Simulations Guide which can be found on the Participatory Simulations Project web site Computer HubNet Setting up a Computer Activity Opening a Computer HubNet model will cause NetLogo to start a server which will allow people to join the activity A dialog will prompt you to enter a unique name that will help participants identify the activity you are running This name will appear if the server is discovered on the clients While this is not necessary entering a name is recommended since it can help reduce confusion over which activity participants should
199. oad RO DOT teens 15 Linux UNIX only bugs e cece eee e inner tetter mms 15 Known issues with computer HubNet eee eeteee eee tee teaeeeaaeeeeeeeeeeseeeseeeeeeeeeeees 16 Planned features nas a 16 Unimplemented StarLogoT priMitiVeS cccoooooocccnncccnnnnnononncnnnnnnnnnnnonnnnnnnnnnccnnnnnnnnnnnnnccnnnnnns 16 ContactinQ US ni 17 WeOD SO a A A A tte E NE SE 17 Ecedback Questions ElC sa reste eis satin Caia site Dra 17 ReportingiBUAS sem feces cases Sta E dad SANS suspends cawadinas tata AD E E Era a 17 Sample Model Rar ara 19 ACP A a SUNS UNS na UT pai dd 19 BRA DR ER E DTD RR CEO ERREI ROO AR RR 21 Thinking With Models ee a ia e Sosa Usb emma ganas 22 Wihats NOXI ia A as E sda O A tad EEE LTDA US Minuet aman 22 Tutorial41 ModelS sis iss eck Sas dace ahead eh lenda antas in Soo da ea Fole pin Seiad ata Lewd no ined a deen da sda de IA 23 Sample Model Wolf Sheep Predation cccccccccsssscccceeeceeeesseseenneeeeeeessseseseeeeeeeeeeeessssaaes 23 Controlling the Model Buttons caia dei 24 Adjusting Settings Sliders and Switches ccccccccsssssssscsceeessssscesesseeesesssssssssseeeesessseeessees 25 Gathering Information Plots and MONItOFS cccconncononcconnnonocnnnnanononononcccnnnnnnnoncncnnnnnnnnnnnnnnnos 27 NetLogo 2 0 2 User Manual Table of Contents Tutorial 1 Models POTS sh escrv A A eck cee RR ce ed 27 MONTOS it 27 Controlling the Graphics WiNdOW cccccononocon
200. occccccnnocononnonoccccnonnnnnnncncnncnconnnnnnnnennrrrnnnnnnnnnnnr rr rnnnnnnnannnnnes 125 Generals scarce e sadia te pes a DOS A ad dedo Ru SR a care ST Esq ET Sa 126 DOWMIOAINO Las e A E siden AGUAS RIA CNGR E adh TOR READ SRS Cn AGO AA 129 ADDICTS ii id 129 USADO A AAA dr 130 A A RO 133 Primitives Dictionna Ve coca 137 Calsqones OL PARTIES ui a 137 Tones aea ai o a AOR OG El 137 Patch related priMitiVeS cooccccccncccnnccnnncnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnineninnniss 137 Agentset primitiVeS iii le ai 137 Col ries andadas 137 Control flow and logic PEMIIVOS omar ici il ereta 138 Display priMitiVES oooooocococcconccnncconnnonnnonnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnnninenss 138 HubNet priMilIVeSc ainda aaa add lidia 138 INPUVOUTPUE primitive Se pnan a ei piada atoa A lived a 138 Elle PriMIIVOS a e aa eds dda ces an E a linea a a a ais 138 ASINADA EAEE E E A A E E E EA E T 138 NetLogo 2 0 2 User Manual Table of Contents Primitives Dictionary Stringi priMiliV is 138 Mathematical priMitiVES ccooccoccconcconcconccnnnnnnnnnnnnonononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnss 138 Plotting PriMitiVES ccocccccccnncnnncnnncnnnnnnnennnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninneinnniss 139 BUEN AA ida 139 clearcallel asia AAA GA 145 ClEAr OFapNGS CO esses asi gerrieri EE AR shank Canute site GRASS ag 145 CICALSQUIDU CO A ara E R
201. odel or code you are having trouble with If possible attach a complete model e Your system information NetLogo version OS version Java version and so on This information is available from NetLogo s About NetLogo menu item 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 17 18 NetLogo 2 0 2 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
202. oes ask turtles orask 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 used each turtle or patch runs the given code over and over again so they can become and remain out of sync with each other At present this capability is very rarely used in the models in our Models Library A model that does use the capability is the Termites model in the Biology section of Sample Models The go button is a turtle forever button so each termite proceeds independently of every other termite and the observer is not involved at all This means that if for example you wanted to add a plot to the 76 Programming Guide NetLogo 2 0 2 User Manual 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 the user presses 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 un
203. of the decimal point 186 Primitives Dictionary NetLogo 2 0 2 User Manual show precision 1 23456789 3 gt 17235 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 pxcor pycor pxcor pycor 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 directly accessed by any turtle standing on the patch See also_xcor ycor R random random number If number is positive reports a random integer greater than or equal to 0 but strictly less than number If number is negative reports a random integer less than or equal to 0 but strictly greater than number If number is zero the result is always 0 as well 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 Primitives Dictionary 187 NetLogo 2 0 2 User Manual show random 3 7 prints 0 1 Or 2 show random 3 po prints 0 L or 2
204. of the turtle you want to inspect into the who field and press return The 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 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 Tutorial 2 Commands 39 NetLogo 2 0 2 User Manual 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 Graphics Window 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
205. 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 pseudorandom numbers Some other primitives also make random choices 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 models runs can be reproducible 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 Gq 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
206. ogo 2 0 2 User Manual 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 graphics window as you might have noticed We can correct this problem to an arbitrary degree by diffusing more times Replace the line 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 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 Mayb
207. ogo 2 0 2 User Manual Turtles have coordinates too xcor and ycor A patch s coordinates are always integers but a turtle s coordinates can have decimals This means that a turtle can be positioned at any point within its patch it doesn t have to be in the center of the patch 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 ert 10 7 make 10 new turtles end to go ask turtles E
208. ol to analyze your results However the new version already has the following advantages over the old one e you can vary any global variables not just sliders but also switches and choices and any variable declared in the procedures tab and the values they range over can be any values not just numbers anymore e you can enter arbitrary code for setup and go now you re not tied to using buttons that exist in your model e you can vary variables in any order you want rather than BehaviorSpace choosing the order for you e you can collect any result type you want not just numbers anymore The documentation for the the new version is still sketchy if you have questions please write feedback ccl northwestern edu 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 The need for this type of experiment is revealed by the following observations Models often have many settings each of which can take a range of values Together they form what in mathematics is called a parameter space for the model whose dimensions are the number of settings and in
209. ombone 59 Tuba 60 Muted Trumpet 61 French Horn 62 Brass Section 63 Synth Brass 1 64 Synth Brass 2 NetLogo Sound Extension NetLogo 2 0 2 User Manual 122 123 124 129 126 127 128 Breath Noise Seashore Bird Tweet Telephone Ring Helicopter Applause Gunshot 123 NetLogo 2 0 2 User Manual 124 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 What language is 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 written a model of lt x gt e Are NetLogo models runs scientifically reproducible Downloading e The download form doesn t 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
210. on so it s important that you provide adequate documentation 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 Occl northwestern edu with questions as we may be able to find a workaround or provide additional guidance where our documentation is thin Hearing from users of this API will also allow us to appropriately focus our efforts for future releases We are committed to making NetLogo flexible and extensible and we very much welcome your feedback 116 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 Caution The controlling facility is still in an early stage of development Therefore it is considered experimental It is likely to continue to change and grow Code you write using it now may need changes in order to continue to work in future NetLogo versions e An Example e Other Options e Conclusion The NetLogo API Specification contains further details An Ex
211. on 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 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 126 FAQ Frequently Asked Questions NetLogo 2 0 2 User Manual 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 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 For example NetLogo 2 0 1 now includes APIs so that NetLogo can be controlled from external Java code and users can write 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 StarLogo
212. 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 display button are useful if you re impatient and want a model to run faster When shapes are turned 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 display button freezes the display The model continues to run in the background and plots and monitors still update but if you want to see what s happening in the graphics window you need to unfreeze the display by turning the switch back on Most models run much faster when the display is frozen The size of the Graphics Window 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 Graphics Window 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
213. on primitive for collecting the set of turtles or turtles of a particular breed standing on a patch or set of patches added new i felse value reporter lets you put conditionals in reporters this is the same as what StarLogoT called i felse report added new in radius nowrap reporter like in radius but doesn t wrap around screen edges the display primitive now has the additional function of forcing an immediate screen update since the graphics window in NetLogo 2 0 sometimes skips frames new primitives turt les from and patches from provide a powerful new way to construct agentsets 4 random one of and random n of now work on lists too not just agentsets the show primitive now puts double quotes around strings so you can distinguish them from other values there is also a new write primitive that behaves the same way but doesn t show the agent 4 butfirst and but last now cause a runtime error if given an empty list as input the color constants red blue and so on are now floating point numbers not integers since turtle and patch colors are always floating point the display and no display commands may now be used by turtles and patches as well as by the observer primitives such as import world and hubnet set client interface now interpret relative pathnames as relative to the location of the model not relative to the location of the application old models will automatically be updated to reflect the following
214. oother screen updates but may make the button run more slowly 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 end 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 turtles 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 O degrees at twelve o clock north fd 1 Each turtle moves forward one step in the new direction it just set its heading to 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 hap
215. orSpace Guide NetLogo 2 0 2 User Manual positive the slope the better decreasing the more negative the better or constant the closer to 0 the better Relative weight menu Determines the relative importance of the slope of the data compared to how well it fits a line or exponential curve see slope type menu If 60 is chosen then 60 of the data s rank comes from its slope how much it is increasing decreasing or constant and 40 comes from line and curve fitting error So a value of 100 means only slope is considered while a value or O means only the error is considered e If you do not care about seeing strictly linear or exponential behavior in the run data you should use high relative weight values and otherwise use low ones Fitness landscape Consists of a grid of squares each of which represents the model run whose slider values were the current values of the constant sliders below and the ith and jth values of the two sliders on the grid s axes where i is the horizontal index of the square and is the vertical The entire grid thus represents all runs in which the constant sliders had their current values the current values being the ones displayed on the set of slider components held constant below the grid This grid earns the name fitness landscape because the squares of which it is composed each has a fitness value expressed by the color of the square enabling you to see a landscape of colors denoting regions of
216. ote stop instrument stop music drums drums Reports a list of the names of the 47 drums for use with play drum instruments NetLogo Sound Extension 119 NetLogo 2 0 2 User Manual instruments Reports a list of the names of the 128 instruments for use with play note start note and stop note 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 60 120 NetLogo Sound Extension NetLogo 2 0 2 User Manual stop instrument stop instrument instrument Stops all notes of an instrument 7 stop all cello notes stop instrument CELLO stop music stop music Stops all notes Sound names Drums 35 Acoustic Bass Drum 59 Ride Cymbal 2 36 Bass Drum 1 60 Hi Bongo 37 Sid
217. pen 46 Tutorial 3 Procedures NetLogo 2 0 2 User Manual 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 once 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 T 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 T gt P gt or O gt 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 T gt commands is identical to O gt ask turtles commands and P gt commands is identical to O gt ask patches commands Play around It s easy and the results are immediate and visibl
218. phics Window on the clients are not exactly the same the Computer HubNet clients will not mirror the model s Graphics Window If you verified that none of the above conditions apply and mirroring is still not working for you please contact us We may be able to help you solve the problem or it might be a bug 100 HubNet Guide NetLogo 2 0 2 User Manual If your situation does not fall into one of the above problem descriptions please_send us a bug report Known Computer HubNet Issues If HubNet malfunctions please send us a bug report See the Contact Us section for instructions Known bugs all systems 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 Increasing the number of clients can increase the response time for clients e There are situations that require the clients to force quit the client application For example If the network connection is lost by the clients or the server even just for a few minutes the clients and or the server might need to be forcibly quit 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 conne
219. ppened to the shape of the Graphics Window e Press the setup button Now you can see the new patches you have created e Edit the Graphics Window again e Change the patch size to 20 and press OK What happened to the size of the Graphics Window Did its shape change Editing the Graphics window also lets you change three other settings the font size of labels whether the Graphics Window uses shapes and whether turtles are drawn in their exact positions or whether they snap to fixed grid positions Feel free to experiment with these 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 31 NetLogo 2 0 2 User Manual Sample Models The Sample Models section is organized by subject area and currently contains more than 140 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 model
220. pposed 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 of steps in the direction of its heading The steps are 44 Tutorial 3 Procedures NetLogo 2 0 2 User Manual 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 on the Graphics Window 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 45 NetLogo 2 0 2 User Manual gt 994 More Editing Button Agent s Observer HA Display Name go Code v Forever Y Force display update after each run Checking this box causes sm
221. press return What happens Just as there are Turtle Monitors there are also Patch Monitors Patch monitors work very similarly to Turtle Monitors Can you make a patch monitor and use it to change the color of a single patch If you try to have the observer ask patch 0 set pcolor blue you ll get an error message Command Center Clear ERROR Expected a number here rather than a list or block O gt ask patch set pcolor blue 40 Tutorial 2 Commands NetLogo 2 0 2 User Manual 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
222. proving 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 2 0 2 August 6 2004 e system our bundled Java VM for Windows is now Sun 1 4 2_05 was 1 4 2_04 e content improved models Buffer no longer unverified Random Balls bugfix all Code Examples now have a copyright notice that clarifies that use of the code in them is unrestricted new code examples Network Example Vision Cone Example Sound Workbench Percussion Workbench Beatbox Composer GasLab With Sound e features 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 our extensions API documentation and code examples for the sound extension are included and the Java source code is available from our website e engine fixes extension jars can now be stored in the extensions folder in the NetLogo folder making them available to all models 4 fixed 2 0 1 only bug in ile read primitive that caused it to fail on larger files fixed bug in sort by primitive where the original list was altered instead of a copy being made fixed bug in histogramming where values equal to the x max were assigned to the previous bin this was arguably acceptable for floating point data but simply incorrect for integer data such values are now considered to fall outside th
223. ption 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 194 Primitives Dictionary NetLogo 2 0 2 User Manual right rt right number The turtle turns right by number degrees If number is negative it turns left round round number Reports the integer nearest to number If the decimal portion of number is exactly 5 the number is rounded in the positive direction Note that rounding in the positive direction is not always how rounding is done in other software programs In particular it does not match the behavior of StarLogoT which always rounded numbers ending in 0 5 to the nearest even integer The rationale for this behavior is that it matches how turtle coordinates relate to patch coordinates in NetLogo For example if a turtle s xcor is 4 5 then it is on the boundary between a patch whose pxcor is 4 and a patch whose pxcor is 5 but the turtle must be considered to be in one patch or the other so the turtle is considered to be in the patch whose pxcor is 4 because we round towards the positive numbers show round 4 2 gt 4 show round 4 5 gt 5 show round 4 5 gt 4 run run string This agent interprets the given string as a sequence of one or more NetLogo commands and runs them The code runs in the agent s curre
224. puts 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 range will not cause runtime errors but will produce 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 Programming Guide 81 NetLogo 2 0 2 User Manual Floating point accuracy When using floating point numbers you should be aware that due to the limita
225. r 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 122 NetLogo 2 0 2 User Manual Pipe 73 Piccolo 74 Flute 75 Recorder 76 Pan Flute 77 Blown Bottle 78 Shakuhachi 79 Whistle 80 Ocarina Synth Lead 81 Square Wave 82 Sawtooth Wave 83 Calliope 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 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 NetLogo Sound Extension 58 Tr
226. r Manual In reporter use 21 and 2 to refer to the two objects being compared reporter should be true if 21 comes strictly before 2 in the desired sort order and false otherwise 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 Mar Woo Ay sprout sprout number commands 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 breeds or whatever sprout 1 set color red 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 until they are fully initialized sqrt sqrt number Reports the square root of number stamp stamp color Sets the color of the patch under the turtle to the given color repeat 30 stamp yellow fd 3 rt 6 7 the turtle records its arched path contrast to the 7 effect of pen down standard deviation standard deviation list Reports the unbiased statistical standard deviation of a list of numbers Ignores other t
227. rap agent k E 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 150 Primitives Dictionary NetLogo 2 0 2 User Manual distancexy xcor ycor Reports the distance from this agent to the point xcor ycor The distance from a patch is measured from the center of the patch 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 Reports the turtle heading between O and 359 degrees in the direction of the minimum 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
228. re if you think the actual 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 may 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 Buttons and display updates Programming Guide 75 NetLogo 2 0 2 User Manual When you edit a button there is a checkbox called Force display 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 care more about smooth animation than raw speed you should uncheck the box but if you care more about smooth animation you should leave it checked 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 graphics window 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 imme
229. re the individual squares in the grid Tutorial 1 Models 29 NetLogo 2 0 2 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 Think 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 30 Tutorial 1 Models NetLogo 2 0 2 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 ha
230. ries 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 Models can be saved as applets to be embedded in web pages 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 reproducible cross platform e Environment Graphics display supports turtle shapes and sizes exact turtle positions and turtle and patch labels Interface builder w buttons sliders switches choices monitors text boxes What is NetLogo 1 NetLogo 2 0 2 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 BehaviorSpace tool used to collect dat
231. roject web site e Disease A disease spreads through the simulated population of students e Elevators Student controlled elevators demonstrate the relation of velocity and position e Function Activity Students experience the concept of a function by forming themselves into graphs e Gridlock Students use traffic lights to control the flow of traffic through a city e People Molecules Using CBR s Calculator Based Range finders students use their bodies to represent gas molecules e Polling Ask students questions and plot their answers e Regression As students move on screen they see the best fit line of their positions NOTE In addition to the discussion of learning goals and classroom techniques these materials also contain step by step instructions and screen shots As of December 2003 many are out of date and no longer match the actual activities in many respects We are working on updating them In the meantime please use these materials for the discussions but for step by step instructions rely instead on the QuickStart Instructions built into the activities see next section Running an activity You ll find the HubNet activities in NetLogo s Models Library under the HubNet Calculator Activities and HubNet Computer Activities folders In each of the activities you ll see a box on the screen labeled QuickStart Instructions It contains step by step instructions on how t
232. rrently down You can set this variable to put a turtle s pen down or pick it back up again See also pen down pen up plabel plabel This is a built in patch variable It may hold a value of any type The patch appears in the graphics window 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 plabel color 184 Primitives Dictionary NetLogo 2 0 2 User Manual plabel color This is a built in patch variable It holds a number greater than or equal to O and less than 140 This number determines what color the patch s label appears in if it has a label You can set this variable to change the color of a patch s label All patch variables can be directly accessed by any turtle standing on the patch See also 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 in
233. rtles and patches note that NetLogo adds import world though e miscellaneous seldom used plotting reporters such as plot pencolor pp plotlist pp plotpointlist ppinterval ppxcor ppycor etc ebit bitand bitneg bitor bitset bitstring bitxor make bitarray rotate left rotate right shift left shift right e close movie open movie setup movie movie snapshot snapshot e load pict e camera brightness camera click camera init camera set brightness enetlogo directory project directory project name project pathname save project 16 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 m
234. ru end to do plots set current plot Turtles at Peaks plot count turtles with elevation gt highest 100 end Tutorial 3 Procedures 57 58 NetLogo 2 0 2 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 In NetLogo you have the choice of or 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 0 Graphics Window 4 Command Center Procedures Tab Information Tab Errors 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 new model The functions available from the menus in the menubar are listed in the following chart Chart NetLogo Menus Starts a new model pens any NetLogo model on your computer A collection of demonstration models ave the current model ave As Save the current model using a different name ave As Applet Used to save a web page in HTML
235. s 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 graphics 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 graphics window control strip to freeze the display Note that display and no display operate independently of the switch in the graphics window control strip that freezes the display See also display no label no label This is a special value used to remove labels from turtles and patches 178 Primitives Dictionary NetLogo 2 0 2 User Manual 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 set other random one of other turtles her if other nobody set color of other red not not boolean Reports true if boolean is false otherwise
236. s 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 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 112 Extensions Guide NetLogo 2 0 2 User Manual 1 Write 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 nlog
237. s 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 those 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 72 Programming Guide NetLogo 2 0 2 User Manual 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 containi
238. s 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 you later when you re extending existing models or building new ones For example if you wanted to put a histogram within your model you d look at Histogram Example to find out how HubNet 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 32 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
239. s in the 0 to 140 range This is the same wrapping that is done automatically if you assign an out of range number to the color turtle variable or pcolor patch variable show wrap color 150 gt 10 show wrap color 10 gt 130 write write value This command will output value which can be a number string list boolean or nobody to the Command Center not followed by a carriage return unlike_print and_show The calling agent is not printed before the value unlike_show Its output will also includes quotes around strings and is prepended with a space write hello world 214 Primitives Dictionary NetLogo 2 0 2 User Manual gt hello world See also_print show and_type X xcor xcor x 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 and lower right quadrants turn blue Y ycor ycor This is a built in turtle variable It holds the current y coordinate of the turtle This is a floating point number not an integer You can set this v
240. s into a list append strings 2 Teacher Variable 4 Append Lists You should note that you must always save the information into the variable st r0 when you are sending or receiving information from the calculators You can t use any other variable 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 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 choices 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 HubNet Authoring Guide 107 NetLogo 2 0 2 User Manual interface element tg Move Left Move Left step size step size all in one step all in one step Location Location Be aw
241. s shown below Command Center Clear O gt ask patches set pcolor yellow e Type in the white box at the bottom of the Command Center the text shown below Command Center Clear O gt ask patches set pcolor yellow o gt ask turtles set color brown 34 Tutorial 2 Commands NetLogo 2 0 2 User Manual Was the result what you expected Your Graphics Window should have a yellow background with a line of brown cars in the middle of the window 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 Clear O gt ask patches set pcolor yellow O gt ask turtles set color brown o Observer Patches e Choose Turtles from the popup menu e Type set color pink and pre
242. s 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 ert 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 number report number end to report first turtle report who 0 reports true or false end Primitives Dictionary 205 NetLogo 2 0 2 User Manual towards towards nowrap towards agent towards nowrap agent x 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 wil
243. screen edge 1 Note You can set the size of the Graphics Window only by editing it 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 196 Primitives Dictionary NetLogo 2 0 2 User Manual 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 x Reports this turtle or patch ask turtles with self myself die 7 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 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 being included as a sublist Examples make this clearer show sentence 1 2 gt 1 2 show sentence 1 2 3 gt 1 2 3 show sentence 1 2 3 gt 1 2 3 show sentence 1 2 3 4 gt 1 2 3 4 show sentence 1 2 3 4 5 3 3 7 gt 1234 5 6 7 Primitives Dictionary 197 NetLogo 2 0 2 User Manual set set variable value Sets var
244. se surprises are exciting and provide excellent opportunities for learning Some people have found it helpful to print out the tutorials in order to work through them When the tutorials are printed out there s more room on your computer screen for the NetLogo model you re looking at Sample Model Wolf Sheep Predation We ll open one of the Sample Models and explore it in detail Let s try a biology model Wolf Sheep Predation a predator prey population model e Open the Models Library from the File menu NetLogo MIES Edit Tools Zoon 8 New sn tl Open 0 ir 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 Graphics Window is empty all black To begin the model you will first need to set it up Tutorial 1 Models 23 NetLogo 2 0 2 User Manual e Press the setup button What do you see appear in the Graphics Window
245. sing all sorts of NetLogo modeling features buttons sliders monitors plots and the graphics window 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 documentation about NetLogo the Interface Guide section of the manual walks you through every element of the NetLogo interface in order and explains its function For a detailed description and 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 Tutorial 3 Procedures 55 NetLogo 2 0 2 User Manual 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 elevat
246. sion 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 Can save the contents of the graphics window Of the interface tab Yes using Export Graphics on the File menu or by right clicking on Mac control clicking the graphics window or using the export graphics command 132 FAQ Frequently Asked Questions NetLogo 2 0 2 User Manual 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 NetLogo itself does not have this capability presently but there are many third party software packages that let you capture movies from any running application Another option would be to use the export graphics Of export interface commands to save a series of snapshots of the model then use some other tool to convert the snapshots into a movie file This should produce smaller files than the other technique 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
247. ss 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 Graphics Window look like now Tutorial 2 Commands 35 NetLogo 2 0 2 User Manual Do you notice any differences between these two commands and the observer commands from earlier The observer oversees the world and therefore can give 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 Wor
248. t 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 procedures 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 65 NetLogo 2 0 2 User Manual f Y Interface Information Procedures Errors E Find E Find Again WHAT IS IT This model explores the stability of predator prey ecosystems The construc model is described in two papers by Wilensky amp Reisman referenced below Su called unstable when they tend to result in extinction for one or more speci In contrast systems are stable when they tend to maintain themselves over t fluctuations in population sizes There are two main variations to this mode In the first variation wolves and sheep wonder randomly around the landscap wolves Look for sheep to prey on Each step costs the wolves energy and the sheep in order to replenish their energy when they run out of energy they the population to continue each wolf or sheep has a fixed probability of re ench time lt ten This wvarintian nradires interectinn namilatian d
249. t index index 1 7 every 2 seconds index is incremented See also_wait exp exp number Reports the value of e raised to the number power Note This is the same as e number export graphics export interface export output export plot export all plots export world export graphics filename export interface filename export output filename export plot plotname filename export all plots filename export world filename Primitives Dictionary 153 NetLogo 2 0 2 User Manual export graphics writes the current contents of the graphics window 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 not just the graphics window export output writes the contents of the output portion of the Command Center to an external file given by the string filename export plot writes the x and y values of all points plotted by all the plot pens in the plot given by the string plotname to an external file given by the string filename If a pen is in bar mode mode 0 and the y value of the point plotted is greater than 0 the upper left corner point of the bar will be exported If the y value is less than 0 then the lower left corner point of the bar will be exported export all plots writes every plot in the current model to an external file given by the string fi
250. t nlogo 7 When clients log in they will will get the interface described in the file 7 Disease client nlogo in the clients subdirectory of the model directory This primitive must be called before you try to use HubNet calling the hubnet reset reporter so NetLogo can know which type of HubNet you are going to be using These primitives are usually best called from the startup procedure of the NetLogo model since they should only be called once in a model Data extraction The data extraction primitives are 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 check 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
251. t s safe to pause a model by stopping a forever button then make it go on by pressing the button again You can also stop a model with the Halt item on the Tools menu but you should only do this if the model is stuck for some reason Using Halt may interrupt the model in the middle of an action and as the result the model could get confused e If you like experiment with the setup and go buttons in the Wolf Sheep Predation model 24 Tutorial 1 Models NetLogo 2 0 2 User Manual Do you ever get different results if you run the model several times with the same settings 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 Como Grass settings 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
252. tLogo 2 0 2 User Manual 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 be of AZ show random poisson 3 4 7 prints a Poisson distributed random integer with a 77 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 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 nu
253. te 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 i current heading at the patch 1 unit away and turns ar that patch green note that this might be the same pat patch the turtle is standing on See also patch patch at patch at heading and distance 182 Primitives Dictionary NetLogo 2 0 2 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 7 if there are many more patches than turtles this will 7 run much faster than patches with any turtles here See also_turtles
254. th e Random Numbers e Strings e Turtle Shapes e File I O Agents The NetLogo world is made up of agents Agents are beings that can follow instructions Each agent can carry out its own activity all simultaneously In NetLogo there are 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 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 Graphics window Programming Guide 67 NetL
255. the same locations in the string The potential resolution of the clock is milliseconds Whether you get resolution that high in practice may vary from system to system depending on the capabilities of the underlying Java Virtual Machine show get date and tim gt 01 19 36 685 PM 19 Sep 2002 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 Primitives Dictionary 161 NetLogo 2 0 2 User Manual H hatch hatch number commands Each turtle creates number new turtles each identical to itself and tells the new turtles to run commands This is useful for giving the new turtles different colors headings breeds or whatever 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
256. 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 Primitives Dictionary 165 NetLogo 2 0 2 User Manual hubnet message waiting This looks for a new message sent by the clients It reports true if there is one and false if there is not See the HubNet Authoring Guide for details hubnet reset hubnet reset Starts up the HubNet system HubNet must be started to use any of the other hubnet primitives with the exception of hubnet set client interface See the HubNet Authoring Guide for details 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
257. til 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 ask 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 Procedures advanced Here are some more advanced features you can take advantage of when defining your own procedures Procedures with inputs Your own procedures can take inputs just like primitives do To create a procedure that accepts inputs include a list of input names in square brackets after the procedure name For example to draw polygon num sides size pd repeat num sides fd size rt 360 num sides Programming Guide 77 NetLogo 2 0 2 User Manual 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 spec
258. time Let s take a look and see what would happen to the sheep if we change one of the settings e Turn the grass switch on e Press setup and go and let the model run for a similar amount of time as before What did this switch do to the model Was the outcome the same as your previous run Just like buttons switches have information attached to them Their information is set up in an on off Tutorial 1 Models 25 NetLogo 2 0 2 User Manual format Switches turn on off a separate set of directions These directions are usually not necessary for the model to run but might add another dimension to the model Turning the grass switch on affected the outcome of the model Prior to this run the growth of the grass stayed constant This is not a realistic look at the predator prey relationship so by setting and turning on a grass growth rate we were able to model all three factors sheep wolf and grass populations Another type of setting is called a slider Sliders are a different type of setting then a switch A switch has two values on or off A slider has a range of numeric values that can be adjusted For example the initial number sheep slider has a minimum value of 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 s
259. tinuous 19 9999 is white but 20 0 is black Primitives Dictionary 139 NetLogo 2 0 2 User Manual The available color names are listed below See also the_rgb and hsb primitives black 0 gray 5 white 9 9999 red 15 orange 25 brown 35 yellow 45 green 55 lime 65 turquoise 75 cyan 85 sky 95 blue 105 violet 115 magenta 125 pink 135 A abs abs number Reports the absolute value of number show abs 7 gt 7 show abs 5 gt 5 acos acos number Reports the arc cosine inverse cosine of the given number The input must be in the range 1 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 condition1 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 140 Primitives Dictionary NetLogo 2 0 2 User Manual 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 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 as in sta
260. tions 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 technique is to use only integers cents internally then divide by 100 to get a result in dollars for display to the user 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 pseudorandom 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 pseudorandom numbers are actually desirable That s
261. tles 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 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 208 Primitives Dictionary NetLogo 2 0 2 User Manual breeds cats dogs hamsters turtles own eyes legs 7 applies to all breeds cats own fur kittens hamsters own fur cage dogs own hair puppies See also_globals patches own 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 U uphill uphill patch variable x Reports the turtle heading between 0 and 359 degrees in the direction of the maximum
262. torial 3 Procedures 49 NetLogo 2 0 2 User Manual 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 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 Tool
263. uctions 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 modified These simulations address many content areas in the natural and social sciences including biology and medicine physics and chemistry mathematics and computer science and economics and social psychology Several model based inquiry curricula using NetLogo are currently under development NetLogo can also power a classroom participatory simulation tool called HubNet Through the use of networked computers or handheld devices such as Texas Instruments 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 se
264. ue may be of any type but is typically a string if yes user choic Set up the model Lice 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 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 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 reports a string with the absolute file path or false if the user cancels 210 Primitives Dictionary NetLogo 2 0 2 User Manual Note that no file is ever created or overwritten with this reporter file open user choose new fil j 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
265. uman participation Since HubNet builds upon NetLogo we recommend that before trying HubNet for the first time you should be familiar with the basics of NetLogo Teacher workshops For information on upcoming workshops and NetLogo and HubNet use in the classroom please contact us at feedback ccl northwestern edu 96 HubNet Guide NetLogo 2 0 2 User Manual Getting Started With HubNet Using NetLogo We recommend that you become familiar with NetLogo itself before using the HubNet technology You can become familiar with NetLogo by trying out some of the models in the Models Library Open the Models Library from the File menu in NetLogo Then click on a model that you want to try and press the Open button The Information tab in each of the models gives background information and instructions Other sections of the NetLogo User Manual may be helpful when learning NetLogo We suggest that beginning users focus on the section_Tutorial 1 Running Models If you have any questions about NetLogo feel free to E mail us You can reach us at feedback ccl northwestern edu HubNet Activities Below are the current HubNet activities that are fully developed Be aware that some of these models have only been implemented for one type of HubNet For many models you will find its educational goals and suggested ways to incorporate them into your classroom in the Participatory Simulations Guide which can be found on the Participatory Simulations P
266. umbers but differently for negative numbers modes modes list Reports a list of the most common item or items in list The input list may contain any NetLogo values If the input is an empty list 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 Reports true if the mouse button is down false otherwise Note If the mouse pointer is outside of the NetLogo graphics window mouse down will always report false 176 Primitives Dictionary NetLogo 2 0 2 User Manual mouse xcor mouse ycor mouse xcor mouse ycor Reports the x or y coordinate of the mouse in the Graphics Window 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 NetLogo graphics window reports the value from the last time it was inside 77 to make the mouse draw in red if mouse down set pcolor of patch at mouse xcor mouse ycor red myself myself ast k E 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
267. un in the main NetLogo window If the Running Experiment window is in the way just move it to a different place on the screen The graphics window 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 window to turn the updating off This will make your model run faster so you ll get your final results sooner 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 BehaviorSpace will then prompt you for the name of a file to save the results to The default name is behaviors csv You can change this 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 If you open the results file in a program that displays it in tabular format you ll see that each individual model run occupies a single column At the top of the column you ll see summary information about the run such as what the settings were for that run and how many ticks the run lasted If you used a numeric reporter to measure your runs then you ll see the min max and mean values of that reporter during the run Finally in the all run data section
268. ur web browser support Java 1 4 1 Here s how to get the right Java 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 application and run the models that way instead e If you re on Windows 98 or newer you need to download the Java browser plug in from http java sun com getjava download himl FAQ Frequently Asked Questions 129 NetLogo 2 0 2 User Manual 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 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 Usage How do change how many patches there are A quick method is to use the three pairs of black arrows in the upper left corner of the graphics window Another method is as follows Select the Graphics Window 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 and Screen Edge Y You can also right click Windows or control click Mac on the Graphics Window to edit it or select it then double click How big can my model be How many turtles p
269. ure after it s been drawn If you make a mistake drawing a geometric figure to fix it remove it and then redraw it Geometric figures that use the key color selected from a drop down menu the default is gray will change according to the value of each turtle s color variable in your model Figures filled with any other color selected from the palette at the top will stay that color regardless of each turtle s color For example you could create cars that always have yellow headlights and black wheels but have bodies of different colors by drawing the bodies in the key color 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 all the detail Simple bold shapes are best When the shape is done give it aname and press the Done button at the bottom of the editing window The shape and its name will now be included in the Shapes Editor s list along with the default shape If you want to use a shape from another model in this model you must first import the shape into this model Press the Import button to select a NetLogo model from which to import one or more shapes Once you have chosen a model a list of that model s shapes will appear Choose as many of these shapes as you like to import into the original model and press the Import button to import Shapes Editor Guide 87 NetLogo 2 0 2 User Manual the shapes Using Shapes in a Model
270. urtles Programming Guide 71 NetLogo 2 0 2 User Manual 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 ca ert 100 z create 100 turtles ask turtles set color red turn them red rt random float 360 77 give them random headings td 30 7 spread them around ask patches if pxcor gt 0 7 patches on the right side set pcolor green 7 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 Usually the observer uses ask to ask all turtles or all patches to run commands You can also use ask to have make an individual turtle or patch run commands The reporters turtle patch and patch at are useful for this technique For example to setup ca CEG 3 make 3 turtles ask turtle 0 tell the first one fd 1 5 to go forward ask turtle 1 tell the second one set color green 77 to become green ask turtle 2 tell the third one Ft 90 J 77 to turn right ask patch 2 2 7 ask the patch at 2 2 set pcolor blue jj 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 ha
271. used to do these tasks Setup In order to make a NetLogo model into a HubNet one it is necessary to establish a connection with the Navigator server in the case of Calculator HubNet and to start a HubNet server in the case of Computer HubNet For Calculator HubNet it is also necessary for NetLogo to tell the Navigator server what variables to send to NetLogo For all forms of HubNet it is also necessary to inform NetLogo what the client interface is All these tasks are done with the following primitives hubnet reset This 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 If this is the first time called for this NetLogo session and you are using Calculator HubNet the TI Navigator Login dialog appears prompting you to input the appropriate information to be able to log into the Navigator system Once you press the Login button NetLogo will attempt to log you into the TI Navigator system and start HubNet If you successfully log into the Navigator system you will not be prompted by this dialog again as long as this session of NetLogo remains open HubNet Authoring Guide 103 NetLogo 2 0 2 User Manual If you are using Computer HubNet you will be prompted by a dialog asking for a unique name for your computer This is an opt
272. 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 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 downhill uphill4 uphill4 patch variable x Reports the turtle heading between 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 Primitives Dictionary 209 NetLogo 2 0 2 User Manual 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 val
273. vert 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 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 order by ID number If you ask patches the patches are scheduled for execution by row left to right within each row and starting with 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 FAQ Frequently Asked Questions 135 NetLogo 2 0 2 User Manual 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 comma
274. y 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 steps of 50 you would enter number 100 50 1000 Or to give it only the values of 100 200 400 and 800 you would enter 90 BehaviorSpace Guide NetLogo 2 0 2 User Manual number 100 200 400 800 Be careful with the brackets here Note that there 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 You can vary as many settings as you want but you must vary at least one Measure runs using this reporter This is where you specify what data you want to collect from each run You must enter a NetLogo reporter that reports the value you want For example if you wanted to record how the population of turtles rose and fell during each run you would enter count CUES You may only enter one reporter but it is still possible to collect multiple measurements by storing the measurements in a list For example if you wanted to record the populations of three different breeds of turtles you could enter list count frogs count mice count birds Set up model with these commands This is where you enter the commands that will be used to begin each model run Typically you will e
275. y 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 output 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 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 _ Primitives Dictionary 159 NetLogo 2 0 2 User Manual 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 9 A show floor 4 5 gt 5 foreach foreach list commands foreach list listn commands With
276. ynamics hiit 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 Errors Tab The Errors tab provides a place for errors to be highlighted and brought to your attention If there are any errors in your code the Errors tab will turn red and come to the front with an explanation of what caused the error When there are no errors the Tab is disabled Interface Information Procedures Erori 2 Find Find Again 8 Compile Procedures set default shape wolves wolf create custom wolves initial number wolves create the wolves then inii set color blcak set energy random 2 wolf gain from food setxy random float screen size x random float screen size y Switching tabs or pressing the Compile button in the toolbar causes your code to be checked for errors 66 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 Procedures advanced e Lists e Ma
277. you ll see what the value of your reporter was at every time step during the entire run Conclusion That concludes the tour of the features of BehaviorSpace The tool is still under development so 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 lope of the data always remains the same The higher the weight selected in the relative weight menu the less this menu selection matters because that means slope matters increasingly more than error Error is determined by attempting to fit the data to either a line or a curve depending on which is chosen and then finding the Least Square Error involved in doing so e Fitting data to a line means finding a function of the form y ax b that best approximates the data e Fitting data to an exponential curve means finding a function of the form y ae bx where e 2 71828 that best approximates the data e If exponential is selected and any run has both positive and negative data values then a warning dialog is brought up saying that the data cannot be fit to an exponential curve and linear is automatically selected this occurs because exponential curves of this form can be either above the x axis when a is positive or below the x axis when a is negative but not both Slope value menu Determines whether it is better for the data to be increasing the more 92 Behavi
278. you press an arrow 28 Tutorial 1 Models NetLogo 2 0 2 User Manual There are more graphics window settings than there s room for in the control strip The More button lets you get to the rest of the settings e Press the More button in the control strip A dialog box will open containing all the settings for the Graphics Window en Editing Graphics Screen Edge X 20 Screen Edge Y 20 Patch Size pixels 8 0 Font Size of turtle and patch labels 10 Y Turtle Shapes Y Exact Turtle Positions amp Sizes Cancel Apply Co 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 Graphics Window You will notice that the pointer turns into a crosshair e Hold down the mouse button and drag the crosshair over the Graphics Window The Graphics Window 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 Graphics Window e Unselect the graphics window by clicking anywhere in the white background of the Interface tab e Press the More 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 a
279. ypes of items show standard deviation 1 2 3 4 5 6 gt 1 8708286933869707 show standard deviation values from turtles energy Primitives Dictionary 203 NetLogo 2 0 2 User Manual 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 forever button the button won t stop until every turtle or patch stops a single turtle or patch doesn t have the power to stop the whole button substring substring string position position2 Reports just a section of the given string ranging between the given positions Note The positions are numbered beginning with 0 not with 1 show substring turtle 1 4 gt urt 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 T 204 Primitives Dictionary NetLogo 2 0 2 User Manual tan tan number Reports the tangent of the given angle Assume

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