Polarainer

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Rainer Mahidin (Author)

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breed [polar-bears polar-bear]

polar-bears-own [hunting-timer]
patches-own [has-ice?]

to setup
  clear-all
  set-default-shape polar-bears "wolf"  ;; Use wolf shape for visibility
  setup-ice
  setup-bears
  reset-ticks
end 

to setup-ice
  ask patches [
    ifelse random-float 100 < initial-ice-percentage [
      set pcolor white
      set has-ice? true
    ] [
      set pcolor blue
      set has-ice? false
    ]
  ]
end 

to setup-bears
  ;; Create 10 small, 10 medium, and 10 large bears
  repeat 10 [
    create-polar-bears 1 [
      set size 0.5
      set color white
      set label "S"
      setxy random-xcor random-ycor
      set hunting-timer 5
    ]
    create-polar-bears 1 [
      set size 1.0
      set color gray
      set label "M"
      setxy random-xcor random-ycor
      set hunting-timer 5
    ]
    create-polar-bears 1 [
      set size 1.5
      set color black
      set label "L"
      setxy random-xcor random-ycor
      set hunting-timer 5
    ]
  ]
end 

to go
  if not any? polar-bears [ stop ]
  shrink-ice
  move-bears
  bears-hunt
  remove-drowned-bears
  plot-data
  tick
end 

to shrink-ice
  ask patches with [has-ice?] [
    if random-float 100 < ice-shrink-rate [
      set has-ice? false
      set pcolor blue
    ]
  ]
end 

to move-bears
  ask polar-bears [
    rt random 50 - random 50
    fd 1
    if not can-move? 1 [ rt 180 fd 1 ]
  ]
end 

to bears-hunt
  ask polar-bears [
    let p patch-here
    ifelse [has-ice?] of p [
      ;; successful hunt
      set hunting-timer 5
    ] [
      ;; no ice → reduce hunting timer
      set hunting-timer hunting-timer - 1
    ]
  ]
end 

to remove-drowned-bears
  ask polar-bears [
    if hunting-timer <= 0 [
      let drown-chance 0
      if size = 1.5 [ set drown-chance 80 ]   ;; large
      if size = 1.0 [ set drown-chance 40 ]   ;; medium
      if size = 0.5 [ set drown-chance 5 ]    ;; small
      if random-float 100 < drown-chance [
        die
      ]
    ]
  ]
end 

to plot-data
  set-current-plot "Bear Population by Size"

  set-current-plot-pen "Small"
  plot count polar-bears with [size = 0.5]

  set-current-plot-pen "Medium"
  plot count polar-bears with [size = 1.0]

  set-current-plot-pen "Large"
  plot count polar-bears with [size = 1.5]
end

There is only one version of this model, created 3 months ago by Rainer Mahidin.

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