Basic Program
to setup
clear-all
reset-ticks
end
to go
tick
wait .4
end
►WRITING CODE
What do you want to do? → When do you want it to happen? → Who is going to do it? → Anything else?
Example: I want to make new turtles. I want it to happen during setup. I want the patches to make the turtles.
Code:
►ASKS
ask turtles [___]
ask turtle x [___]
ask n-of x turtles [___]
ask turtles in-radius x [___]
ask patches [___]
ask patch x y [___]
ask n-of x patches [___]
ask patches in-radius x [___]
ask links [___]
ask link x [___]
ask n-of x links [___]
►COMMANDS
[set
color x]
pcolor x]
size x]
shape “shape”]
heading x]
heading heading + x]
thickness x]
[setxy x y]
[fd x]
[show “hello”]
[crt x]
[sprout x]
[hatch x]
[die]
►LOGIC
if ___ [ ]
ifelse ____ [ ][ ]
►RANDOM NUMBERS
random x
random-xcor random-ycor
if random x < y
►COUNT
if any? ___
if count ___ > x
if count ___ in-radius
ask n-of 3 patches [sprout 1 [setxy random-xcor random-ycor set color blue set size 3]]
This will have 3 random patches each make 1 turtle and give it a random location, color blue, and size 3.
EXAMPLE CODE
WHAT DOES THIS DO?
WHO CAN DO THIS?
ask turtles [set color blue]
asks all turtles to turn blue
observer, patches, turtles, links
ask turtle 4 [set heading 24]
asks turtle with who 4 to set heading to 24 degrees observer, patches, turtles, links
ask n-of 3 turtles [die]
asks 3 random turtles to die
observer, patches, turtles, links
ask turtles in-radius 4 [die]
asks all the turtles in a radius of 4 to die
patches, turtles
ask patches [set pcolor black]
asks all patches to change their color to black
observer, patches, turtles, links
ask patch 3 2 [sprout 1]
asks patch at location (3,2) to make a turtle
observer, patches, turtles, links
ask n-of 7 patches [set pcolor pcolor – 1]
asks 7 random patches to decrease their pcolor by 1 observer, patches, turtles, links
ask patches in-radius 2 [set pcolor 45]
asks all the patches in a radius 2 to set pcolor
patches, turtles
ask links [set thickness 2]
asks all links to set their thickness to 2
observer, patches, turtles, links
ask link 2 [set color 78]
asks link with who 2 to set it’s color to 78
observer, patches, turtles, links
ask n-of 3 links [die]
ask 3 random links to die
observer, patches, turtles, links
EXAMPLE CODE
WHAT DOES THIS DO?
WHO CAN DO THIS?
ask turtles [set color red]
sets turtle or link color
turtles, links
ask patches [set pcolor green]
sets patch color
patches (turtles can set pcolor)
ask turtles [set size 10]
sets turtle size
turtles
ask turtle 1 [set shape “person”]
sets turtle shape
turtles
ask turtle 4 [set heading 90]
sets turtle heading
turtles
ask turtle 3 [set heading heading + 20 ]
increase/decrease turtle heading
turtles
ask links [set thickness 2]
sets link thickness
links
ask turtle 3 [setxy 3 8]
sets turtle location
turtles
ask turtle 0 [fd -2]
turtle(s) moves forward or backward
turtles
ask turtle [if pcolor = green [show “hello!”]]
asks turtle to speak
turtles
crt 3 [set size 2 set shape “cow”]
asks observer to create 4 turtles
observer
ask patch 3 2 [sprout 2 [set size 3]]
asks patches to make baby turtles
patches
ask turtle 0 [if pcolor = yellow [hatch 1]]
asks turtles to make baby turtles
turtles
ask turtle [if pcolor = red [die] ]
asks turtle to die
turtles, links
EXAMPLE CODE
WHAT DOES THIS DO?
if ticks > 10 [ask turtles [set pcolor green]]
if the number of ticks is greater than 10, asks all turtles to turn green
ask turtles [ifelse count turtles > 20 [fd 1][fd 2]]
asks the turtles, if there are more than 20 turtles, move forward 1, otherwise 2
EXAMPLE CODE
WHAT DOES THIS DO?
set heading heading + random 30
this will set the turtle’s heading to it’s current heading + a random amount from 0 to 29
setxy random-xcor random-ycor
this will set the turtle’s location to a random location
if random 100 < 50 [ask turtle 1 [fd 1]]
this will ask turtle 1 to move fd 1 half the time
EXAMPLE CODE
WHAT DOES THIS DO?
ask patches [if any? turtles in-radius 5 [set pcolor red]]
if there are any turtles in a radius of 5, patches turn red
if count turtles > 20 [ask n-of 1 turtle [die]]
if there are more than 20 turtles, then a random turtle will die
ask turtles [if count turtles in-radius 4 > 20 [die]]
if there are more than 20 turtles around the turtle, it will die
BREEDS AND GLOBALS MUST BE ESTABLISHED AT THE VERY BEGINNING OF YOUR CODE - BEFORE THE SETUP FUNCTION
►BREEDS
breed [singular plural]
EXAMPLE CODE
breed [goodguy goodguys]
WHAT DOES THIS DO?
creates a subtype of turtles called goodguy(s)
Breeds create subtypes of turtles and links which you can assign different globals and call with functions independently of each
other. In this example I have created the breed goodguy which I can then create by saying create-goodguys 4 [setxy random-xcor
random-ycor set color yellow set size 3] and then I could have them do things like ask goodguys [set heading heading + random 20
– random 20 fd 1 if any? goodguys in-radius 2 [show “hello friend”]].
►GLOBALS
turtles-own [ ]
patches-own [ ]
links-own [ ]
EXAMPLE CODE
turtles-own [time-since-birth]
WHAT DOES THIS DO?
will give each turtle the characteristic “time-since-birth”
In this example, you’d want to have any turtles created to [set time-since-birth 0] and somewhere in your go
command ask turtles [set time-since-birth time-since-birth + 1] so that the value will increase with each tick.
You could later use this variable by doing something like ask turtles [if time-since-birth > 65 [die]].
►RANDOM USEFUL CODE FRAGMENTS
ask badguy [set heading ( towards min-one-of goodguy [distance myself] ) fd 1]
ask goodguy [ ifelse any? badguy in-radius 7 [set heading ( towards min-one-of goodguy [distance myself] – 180 ) fd 1.2 ][set heading heading + random 30 – random 30 fd 1 ]
ask turtle 0 [create-link-with turtle 1 [set thickness 1 set color red]]
►EXAMPLE PROGRAM
breed [goodguy]
breed [badguy]
to setup
ca
reset-ticks
ask patches [set pcolor green]
create-goodguy 5 [set shape "person" set size 2 set color blue setxy random-xcor random-ycor]
create-badguy 2 [set shape "person" set size 3 set color red setxy random-xcor random-ycor]
end
to go
ask badguy [set heading ( towards min-one-of goodguy [distance myself] ) fd 1]
ask goodguy [ ifelse any? badguy in-radius 6
[set heading (towards min-one-of badguy [distance myself] - 180 ) fd .8]
[set heading heading + random 30 - random 30 fd .6]]
ask goodguy [if count goodguy in-radius 2 > 1 [hatch 1 [setxy random-xcor random-ycor]]]
ask goodguy [if any? badguy in-radius 1 [die]]
wait .3
tick
end