Spatial Prisoner's Dilemma

patches-own [
  cooperate?
  old-cooperate?
  score
  color-class
  Prob
]

to setup
  clear-all
  ask patches [setup-cooperation false update-color]
  ask n-of (cooperators * (count patches)) patches [setup-cooperation true update-color]
  reset-ticks
  update-plot
end 

to setup-1-at-the-center
  clear-all
  ask patches [
    setup-cooperation true
    update-color
  ]
  ask patch 0 0 [
    setup-cooperation false
    update-color
  ]
  reset-ticks
  update-plot
end 

to setup-cooperation [value]
  set cooperate? value
  set old-cooperate? value
end 

to go
  ask patches [update]
  tick
  update-plot
end 

to-report neighborsN
  ifelse n-neighbors = 8 [report (patch-set neighbors self)][report (patch-set neighbors4 self)]
end 

to update
  ask neighborsN [
    ifelse cooperate?
    [set score (count neighborsN with [cooperate? = true])]
    [set score (count neighborsN with [cooperate? = true]) * b]
    set old-cooperate? cooperate?
  ]
  ifelse update-rule = "deterministic" [
    if [score] of max-one-of neighborsN [score] > score [
      set cooperate? [cooperate?] of max-one-of neighborsN [score]
    ]
  ][
    let numberp sum (map [ ?1 -> ?1 ^ m ] [score] of neighborsN with [cooperate?])
    let numberq sum (map [ ?1 -> ?1 ^ m ] [score] of neighborsN)
    ifelse numberq = 0 [set Prob 0][set Prob (numberp / numberq)]
    ifelse random-float 1 <= Prob [set cooperate? true][set cooperate? false]
  ]
  update-color
end 

to update-color
  ifelse old-cooperate?
    [ifelse cooperate?
      [set pcolor blue
       set color-class 1]
      [set pcolor yellow
       set color-class 3]
    ]
    [ifelse cooperate?
      [set pcolor green
       set color-class 4]
      [set pcolor red
       set color-class 2]
    ]
end 

to update-plot
  set-current-plot "Cooperation/Defection numbers"
  plot-histogram-helper "cc" blue
  plot-histogram-helper "dd" red
  plot-histogram-helper "cd" green
  plot-histogram-helper "dc" yellow
end 

to plot-histogram-helper [pen-name color-name]
  set-current-plot-pen pen-name
  histogram [color-class] of patches with [pcolor = color-name]
end