Let’s start with the implementation of a model of termites making piles of wood chips. You start a new NetLogo model and first create the interface. You add to buttons “setup” and “go.” The setup button is at the observer level and will be executed once. The go button is at the observer level and goes forever
Also add two sliders: “number” with a minimum of 1 and a maximum of 300 with a stepsize of 1, and “density” with a minimum of 0 and a maximum of 100 with a stepsize of 1.
Next, you will go to the procedures tab, and define setup as follows
to setup
ca
setup-chips
setup-termites
end
Randomly strew yellow wood chips (patches) with given density
to setup-chips
ask patches [ if random-float 100 < density
[set pcolor yellow ]]
end
Randomly position given number of white termites
to setup-termites
create-turtles number
ask turtles [set color white
setxy random-xcor random-ycor]
end
Before you continue, click on the setup button in the interface. Does it work?
Now we continue with the go command. When you press on go, the termites (turtles), will continuously execute three rules:
- look around for a wood chip and pick it up
- look around for a pile of wood chips
- look around for an empty spot in the pile and drop off the chip
to go
ask turtles [
pick-up-chip
find-new-pile
drop-off-chip
]
end
The pick-up-chip command is defined as follows,
to pick-up-chip
while [pcolor != yellow]
[explore]
set pcolor black
set color orange
end
where explore command is defined as
to explore
fd 1
rt random-float 50 – random-float 50
end
Find a new pile is defined as
to find-new-pile
while [ pcolor != yellow]
[ explore]
end
Finally, drop off chip is modeled like
to drop-off-chip
while [ pcolor != black]
[explore]
set pcolor yellow
set color white
fd 20
end
Click on the “go” button in the interface. What is happening? If you click on the “Settings” and change the dimensions of number of patches on the screen to a larger number, say 100x100 patches. Will the same results appear?