extensions [ sound ]
breed [rabbits rabbit]
rabbits-own
[
energy
food
wood
metal
target
grass-targets
wood-targets
metal-targets
noteset
noteset2
]
Globals
[
lastcount
thiscount
changecount
key
notecount
]
to setup
clear-all
grow-grass-and-woods-and-shit ;; initial grass, wood and metal
set-default-shape rabbits "rabbit"
create-rabbits number [
set color white
setxy random-xcor random-ycor
set energy random 50 ;start with a random amt. of energy - too little and will die in first stage - hey ho.
;; Set initial targets
set grass-targets patches with [pcolor = green]
set wood-targets patches with [pcolor = violet]
set metal-targets patches with [pcolor = grey]
set target min-one-of grass-targets [distance myself]
face target
set noteset one-of [1 3 5 6 8 10 11 12 14 16 17 19 21 23]
set noteset2 one-of [1 3 5 6 8 10 11 12 14 16 17 19 21 23]
set lastcount number
set thiscount number
set changecount 0
set notecount 0
]
reset-ticks
end
to go
if not any? rabbits [ stop ]
grow-grass-and-woods-and-shit ;; entropic feed function
ask rabbits
[
move
set size 1
eat-grass
if energy > hungry ;; bunnies are not interested in resource plunder when they are hungry .. we'll make the hungers relative later
[ cut-woods
mine-metal
reproduce
set size 1.5]
if energy > (hungry * 2)
[set size 2]
if energy > (hungry * 3)
[set size 2.5]
if energy > (hungry * 4)
[set size 3]
if energy > (hungry * 5)
[set size 3.5]
if energy > (hungry * 6)
[set size 4]
if energy > (hungry * 7)
[set size 4.5]
if energy > (hungry * 8)
[set size 5]
death
]
set thiscount count rabbits ;; keychange sequence
if thiscount != lastcount
[
if ( random 256 = 1 ) ;; slow down key changes
[
set changecount thiscount - lastcount
set key one-of [ -2 -4 -6 0 2 3 5 ]
set lastcount thiscount ]
]
set notecount 0
tick
end
to grow-grass-and-woods-and-shit ;; woods only grow in grass, metal only grows on wood. This makes wood scarce and metal scarcer.
ask patches [
if pcolor = black
[ if random-float 1000 < grass-grow-rate
[ set pcolor green ]]
if pcolor = green
[if random-float 1000 < woods-grow-rate
[ set pcolor violet ]]
if pcolor = violet
[if random-float 1000 < metal-grow-rate
[ set pcolor grey ]
] ]
end
to move ;; rabbit procedure
;; diatonic set noteset one-of [1 3 5 6 8 10 11 12 14 16 17 19 21 23]
set noteset one-of [1 4 6 8 11 13 16 18 20 23] ;; pentatonic
;; set noteset2 one-of [1 3 4 6 8 11 13 34 16 18 20 23] ;; minor septatonic
set noteset2 one-of [1 4 8 11 13 16 20 23] ;; minor septatonic thirds
;; set current nearest targets
set grass-targets patches with [pcolor = green]
set wood-targets patches with [pcolor = violet]
set metal-targets patches with [pcolor = grey]
if grass-targets != nobody
[ ;; for now - just go after the grass - wood and metal will be accidents.. later it will depend on needs
set target min-one-of grass-targets [distance myself]
]
if target != nobody
[face target
;; metal makes a bunny go faster
ifelse distance target < (1 + (metal / 10))
[ move-to target ]
[ fd 1 + (metal / 10)]
]
set color white
ifelse ((metal / 10) > 1) and ((metal / 10) <= 2)
[set color yellow
if notecount < 2
[sound:stop-instrument "Rain"
sound:play-note "Rain" (noteset + 60 + key) 20 0.5
set notecount (notecount + 1)]
] ;; orange bunnies got wheels.
[if (metal / 10) > 2
[set color red
if notecount < 2
[sound:stop-instrument "Bird Tweet"
sound:play-note "Bird Tweet" (noteset + 60 + key) 24 0.5
set notecount (notecount + 1)]
]
] ;; red bunnies got ferraris
if count rabbits-here > 1 ;; competition and collision
[
if notecount < 2
[sound:stop-instrument "Guitar Fret Noise"
sound:play-note "Guitar Fret Noise" (noteset + 48 + key) ( 8 + (count rabbits-here * 6)) 0.1
set notecount (notecount + 1)]
]
;; moving takes some energy - and more energy for the weight of wood and metal in tow
set energy energy - ((grass-energy * 0.1) + (metal * 0.02) + (wood * 0.01))
;; moving also wears-out metal
if metal > metal-energy
[set metal metal - (metal-energy * 0.05)]
end
to eat-grass ;; rabbit procedure
;; gain "grass-energy" by eating grass
if pcolor = green
[ set pcolor black
set energy energy + grass-energy
if notecount < 2
[sound:stop-instrument "Glockenspiel"
sound:play-note "Glockenspiel" (noteset + 60 + key) 22 1
set notecount (notecount + 1)]
]
end
to cut-woods ;; rabbit procedure
;; gain "wood" by eating woods
if pcolor = violet
[ set pcolor black
set wood wood + wood-energy
set energy energy - (wood-energy * 0.5)
sound:stop-instrument "Xylophone"
sound:play-note "Xylophone" (noteset + 60 + key) 54 1
]
end
to mine-metal ;; rabbit procedure
;; gain "metal" by mining metal
if pcolor = grey
[ set pcolor black
set metal metal + metal-energy
set energy energy - ( metal-energy * 0.75 )
sound:stop-instrument "Goblins"
sound:play-note "Goblins" (noteset2 + 72 + key) 24 4
]
end
to reproduce ;; rabbit procedure
;; give birth to a new rabbit, but it takes lots of energy and all the wood and metal and only if the bunny is not hungry
if (energy > birth-threshold) and (wood > wood-threshold)
[ set energy energy / 2
set wood wood / 2
set metal metal / 2
sound:stop-instrument "Acoustic Grand Piano"
sound:play-note "Acoustic Grand Piano" (noteset2 + 60 + key) 60 2
hatch 1 [ fd 1 ] ]
end
to death ;; rabbit procedure
;; die if you run out of energy
if energy < 0
[
sound:stop-instrument "Acoustic Bass"
sound:play-note "Acoustic Bass" (noteset2 + 24 + key) 60 8
die
]
end
; Copyright 2001 Uri Wilensky.
; See Info tab for full copyright and license.
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"woods" 1.0 0 -8630108 true "" "plot count patches with [pcolor = violet] / 4"
"wood gathered" 1.0 0 -7500403 true "" "plot sum [wood] of rabbits / 40"
"metal gathered" 1.0 0 -10263788 true "" "plot sum [metal] of rabbits / 40"
"metal" 1.0 0 -16777216 true "" "plot count patches with [pcolor = grey] / 4"
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@#$#@#$#@
## WHAT IS IT?
This project explores a simple ecosystem made up of rabbits, grass, and weeds. The rabbits wander around randomly, and the grass and weeds grow randomly. When a rabbit bumps into some grass or weeds, it eats the grass and gains energy. If the rabbit gains enough energy, it reproduces. If it doesn't gain enough energy, it dies.
The grass and weeds can be adjusted to grow at different rates and give the rabbits differing amounts of energy. The model can be used to explore the competitive advantages of these variables.
## HOW TO USE IT
Click the SETUP button to setup the rabbits (red), grass (green), and weeds (violet). Click the GO button to start the simulation.
The NUMBER slider controls the initial number of rabbits. The BIRTH-THRESHOLD slider sets the energy level at which the rabbits reproduce. The GRASS-GROWTH-RATE slider controls the rate at which the grass grows. The WEEDS-GROWTH-RATE slider controls the rate at which the weeds grow.
The model's default settings are such that at first the weeds are not present (weeds-grow-rate = 0, weeds-energy = 0). This is so that you can look at the interaction of just rabbits and grass. Once you have done this, you can start to add in the effect of weeds.
## THINGS TO NOTICE
Watch the COUNT RABBITS monitor and the POPULATIONS plot to see how the rabbit population changes over time. At first, there is not enough grass for the rabbits, and many rabbits die. But that allows the grass to grow more freely, providing an abundance of food for the remaining rabbits. The rabbits gain energy and reproduce. The abundance of rabbits leads to a shortage of grass, and the cycle begins again.
The rabbit population goes through a damped oscillation, eventually stabilizing in a narrow range. The total amount of grass also oscillates, out of phase with the rabbit population.
These dual oscillations are characteristic of predator-prey systems. Such systems are usually described by a set of differential equations known as the Lotka-Volterra equations. NetLogo provides a new way of studying predatory-prey systems and other ecosystems.
## THINGS TO TRY
Leaving other parameters alone, change the grass-grow-rate and let the system stabilize again. Would you expect that there would now be more grass? More rabbits?
Change only the birth-threshold of the rabbits. How does this affect the steady-state levels of rabbits and grass?
With the current settings, the rabbit population goes through a damped oscillation. By changing the parameters, can you create an undamped oscillation? Or an unstable oscillation?
In the current version, each rabbit has the same birth-threshold. What would happen if each rabbit had a different birth-threshold? What if the birth-threshold of each new rabbit was slightly different from the birth-threshold of its parent? How would the values for birth-threshold evolve over time?
Now add weeds by making the sliders WEEDS-GROW-RATE the same as GRASS-GROW-RATE and WEEDS-ENERGY the same as GRASS-ENERGY. Notice that the amount of grass and weeds is about the same.
Now make grass and weeds grow at different rates. What happens?
What if the weeds grow at the same rate as grass, but they give less energy to the rabbits when eaten (WEEDS-ENERGY is less than GRASS-ENERGY)?
Think of other ways that two plant species might differ and try them out to see what happens to their relative populations. For example, what if a weed could grow where there was already grass, but grass couldn't grow where there was a weed? What if the rabbits preferred the plant that gave them the most energy?
Run the model for a bit, then suddenly change the birth threshold to zero. What happens?
## NETLOGO FEATURES
Notice that every black patch has a random chance of growing grass or
weeds each turn, using the rule:
if random-float 1000 < weeds-grow-rate
[ set pcolor violet ]
if random-float 1000 < grass-grow-rate
[ set pcolor green ]
## RELATED MODELS
Wolf Sheep Predation is another interacting ecosystem with different rules.
## HOW TO CITE
If you mention this model in a publication, we ask that you include these citations for the model itself and for the NetLogo software:
* Wilensky, U. (2001). NetLogo Rabbits Grass Weeds model.
http://ccl.northwestern.edu/netlogo/models/RabbitsGrassWeeds. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.
* Wilensky, U. (1999). NetLogo.
http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.
## COPYRIGHT AND LICENSE
Copyright 2001 Uri Wilensky.
This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License. To view a copy of this license, visit
http://creativecommons.org/licenses/by-nc-sa/3.0/ or send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.
Commercial licenses are also available. To inquire about commercial licenses, please contact Uri Wilensky at
[email protected].
This model was created as part of the projects: PARTICIPATORY SIMULATIONS: NETWORK-BASED DESIGN FOR SYSTEMS LEARNING IN CLASSROOMS and/or INTEGRATED SIMULATION AND MODELING ENVIRONMENT. The project gratefully acknowledges the support of the National Science Foundation (REPP & ROLE programs) -- grant numbers REC #9814682 and REC-0126227.
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