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Using Netlogo

 

AN INTRODUCTION TO NETLOGO
What is Netlogo?
  • Introduction to Computers Models/Modelling as Inquiry
  • Tutorial model (click on view/download mode, choose File>Save Page As> AntPG.nlogo to desktop, then open with Netlogo)
  • Example model (click on view/download model to modify)
  • An "agent-based modeling" program
  • There are two types of agents: "turtles" and "patches"
  • Turtles move around on the patches; the patches are stationery
  • Turtles can interact with each other, patches can interact with each other, and turtles & patches can interact with each other

     

     
Try it out...

Netlogo applets on Serendip

 

Useful sample models, select "Run model in your browser"
to the right of the screencap

 

More models from the User Community
Templates (click here for the complete user manual)

Step 1. Adding buttons to the interface

A. Add a 'setup' button (click for image): Under the Interface tab, click on +Add [button] at the top; type setup in the commands box
B. Add a 'go' button: Add another button, type go in the commands box, and check the "Forever" box

Step 2. Adding code
A. Add a chunk of code for each button: Click on on the "Procedures" tab and add the following code:

 

to setup
clear-all
create-turtles 25 [ use setup commands for turtles here ]
ask patches [ use setup commands for patches here ]
end
to go

ask turtles [ use commands for turtles here ]
ask patches [ use commands for patches here ]
end

 

Step 3. Syntax

  • A procedure is a chunk of code with the format
    to procedure-name
    commands
    end

     

  • Agents are addressed with ask followed by commands in brackets
    ask turtles [forward 1]
    ask patches [set pcolor blue]

     

  • Brackets are also used for some variables and keywords
    ask turtles [set [pcolor] of patch-here orange]
    ask patches with [pcolor = black] [set pcolor yellow]

     

  • Numbers, mathematical operations, etc. are enclosed in parenthesis
    ask (.5 * count turtles) turtles [forward 1]

    = 50% of the total numbers of turtles are asked to move forward 1
     
  • Logic
    if conditions [run these commands]
    ifelse conditions [run these commands] [if not, run these commands

    = if is followed by a set of conditions then the commands set in [brackets] are run if they are met

 

Step 4. Common codes & examples (click here for the complete dictionary)

 

Code What it does Also try  
ask turtles [forward 1] All turtles move forward 1 patch back, left, right, jump
Can use any number, decimals, generate random numbers, ie 10, 5.5, random 50
ask turtles [set xcor 10 set color blue set heading 180] ask patches [set pcolor green] set is used for individual variables like color/pcolor (turtle/patch), xcor/pxcor (turtle/patch), heading, etc. For turtles:
set heading 360
set heading (heading + 10)
set pcolor of patch-here green
set shape "butterfly"
set size "5"
set size size + 1
set [pcolor] of patch-here green

For patches:
ask patch-ahead 5 [set pcolor blue]
random 100 Randomly picks a number between 0 and 99 random-xcor and random-ycor (for turtles), random-pxcor and random-pycor (for patches)
ask patch 0 0 [set pcolor green]
ask turtle 13 [set shape "bug"] ask turtles-at 5 5 [set xcor 0 set ycor 0] 		Patches are identified by their x-coordinate and y-coordinate; Turtles are numbered but also have coordinates. ask turtles with [color = blue] [jump random 50]
ask turtles with [xcor != 0] [set xcor 0] != means without/not equal to
ask patches with [pycor > 5] [set pcolor black]
ask turtles [if [pcolor] of patch-here = green [forward 5]]
ask patches [if any? turtles-here [set pcolor white]] 		A turtle can interact with the patch by asking about it's variables with, for ex, patch-here
A patch can determine if there are turtles on it by asking any? turtles-here		 ifelse [forward 5] [back 5]
if random 10 > 5 [set heading random 360 forward 10]
to go
ask turtles [forward 5]
ask turtles [if xcor > 5 [turn-around]]
end

to turn-around
set heading (heading - 180)
end

You can name a procedure anything, and then put the name in a set of commands for turtles/patches; The turtles/patches will run those commands then return to the first procedure and run the remainder of the commands. to go
ask patches with [pxcor > 5] [check-for-turtles]
end

to check-for-turtles
if any? turtles-here [ask turtles-here [fd 10]]
end

 

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Comments

Judith Lucas-Odom's picture

Net logo

Submitted by Judith Lucas-Odom on Wed, 07/09/2008 - 2:43pm.
This afternoon was a little frustrating trying to figure out how to create my own netlogo piece because my computer refused to let me download the program but I did enjoy the tutorials. I think I will try to use it along with scratch in my classroom but the action potential pattern did not make the right connection today. My neuron pathway was blocked by a exterior output of the extension of my self, my computer! Overall, it was a very productive day!

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