Why won't any water squares spawn in on my netlogo simulation? - netlogo

Question

globals [grass]
;; Sheep and wolves are both breeds of turtle.
breed [sheep a-sheep] ;; sheep is its own plural, so we use "a-sheep" as the singular.
breed [wolves wolf]
turtles-own [energy] ;; both wolves and sheep have energy
patches-own [countdown]
to setup
clear-all
ask patches [ set pcolor green ]
;; check GRASS? switch.
;; if it is true, then grass grows and the sheep eat it
;; if it false, then the sheep don't need to eat
if water? [
if grass? [
ask patches [
set pcolor one-of [green brown blue]
if-else pcolor =[green blue]
[ set countdown grass-regrowth-time ]
[ set countdown random grass-regrowth-time ] ;; initialize grass grow clocks randomly for brown patches
]
]
if grass? [
ask patches [
set pcolor one-of [green brown]
if-else pcolor = green
[ set countdown grass-regrowth-time ]
[ set countdown random grass-regrowth-time ] ;; initialize grass grow clocks randomly for brown patches
]
]
]
set-default-shape sheep "sheep"
create-sheep initial-number-sheep ;; create the sheep, then initialize their variables
[
set color white
set size 1.5 ;; easier to see
set label-color blue - 2
set energy random (2 * sheep-gain-from-food)
setxy random-xcor random-ycor
]
set-default-shape wolves "wolf"
create-wolves initial-number-wolves ;; create the wolves, then initialize their variables
[
set color black
set size 2 ;; easier to see
set energy random (2 * wolf-gain-from-food)
setxy random-xcor random-ycor
]
display-labels
set grass count patches with [pcolor = green]
;;set water count patches with [pcolor = blue]
reset-ticks
end
to go
if not any? turtles [ stop ]
ask sheep [
move
if water? [
if pcolor = blue [
set energy energy = 0
death ;;sheep drowns
]
]
if grass? [
set energy energy - 1 ;; deduct energy for sheep only if grass? switch is on
eat-grass
]
death
reproduce-sheep
]
ask wolves [
move
if water? [
if pcolor = blue [
set energy energy = 0
death
]
]
set energy energy - 1 ;; wolves lose energy as they move
catch-sheep
death
reproduce-wolves
]
if grass? [ ask patches [ grow-grass ] ]
set grass count patches with [pcolor = green]
tick
display-labels
end
to move ;; turtle procedure
rt random 50
lt random 50
fd 1
end
to eat-grass ;; sheep procedure
;; sheep eat grass, turn the patch brown
if pcolor = green [
set pcolor brown
set energy energy + sheep-gain-from-food ;; sheep gain energy by eating
]
end
to reproduce-sheep ;; sheep procedure
if random-float 100 < sheep-reproduce [ ;; throw "dice" to see if you will reproduce
set energy (energy / 2) ;; divide energy between parent and offspring
hatch 1 [ rt random-float 360 fd 1 ] ;; hatch an offspring and move it forward 1 step
]
end
to reproduce-wolves ;; wolf procedure
if random-float 100 < wolf-reproduce [ ;; throw "dice" to see if you will reproduce
set energy (energy / 2) ;; divide energy between parent and offspring
hatch 1 [ rt random-float 360 fd 1 ] ;; hatch an offspring and move it forward 1 step
]
end
to catch-sheep ;; wolf procedure
let prey one-of sheep-here ;; grab a random sheep
if prey != nobody ;; did we get one? if so,
[ ask prey [ die ] ;; kill it
set energy energy + wolf-gain-from-food ] ;; get energy from eating
end
to death ;; turtle procedure
;; when energy dips below zero, die
if energy < 0 [ die ]
end
to grow-grass ;; patch procedure
;; countdown on brown patches: if reach 0, grow some grass
if pcolor = brown [
ifelse countdown <= 0
[ set pcolor green
set countdown grass-regrowth-time ]
[ set countdown countdown - 1 ]
]
end
to display-labels
ask turtles [ set label "" ]
if show-energy? [
ask wolves [ set label round energy ]
if grass? [ ask sheep [ set label round energy ] ]
]
end
but when I run this ( you have to place a on off switch for water? in the wolf sheep predation) it runs as if I made no changes at all. Why is this? How can I fix this?
anything related to water was added to the code by me.

Answer 1

You have two if statements inside the first if water? (in setup), and both respond to grass? So you do turn some patches blue, but then you execute the send if and turn all either brown or green.
Whenever you get confused, make smaller procedures. E.g.,
to color-patches
if grass? [
let patch-colors [green brown]
if water? [set patch-colors [green brown blue]]
ask patches [set pcolor one-of patch-colors]
]
end
One other problem, is that you don't want if pcolor = [green blue], which (i) will always be false and (ii) is trying to set a regrowth countdown on water patches.