MARAS

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Junnan Lyu (Author)

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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; GLOBALS & TURTLE VARIABLES
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

globals [
  percent-believers
  percent-similar
  percent-unhappy
]

turtles-own [
  believer?
  personal-faith
  type-id

  happy?
  similar-nearby
  other-nearby
  total-nearby
]

to setup
  clear-all
  ask patches [ set pcolor white ]


  ask patches [
    if random 100 < density [
      sprout 1 [
        set size 1.3


        set type-id 1 + random num-types


        if type-id = 1 [
          set personal-faith 2           ;; logistic(2) ~ 0.88
          set believer? (random-float 1 < 0.9)
        ]
        if type-id = 2 [
          set personal-faith 0.5         ;; logistic(0.5) ~ 0.62
          set believer? (random-float 1 < 0.6)
        ]
        if type-id = 3 [
          set personal-faith -0.5        ;; logistic(-0.5) ~ 0.38
          set believer? (random-float 1 < 0.3)
        ]
        if type-id = 4 [
          set personal-faith -2          ;; logistic(-2) ~ 0.12
          set believer? (random-float 1 < 0.1)
        ]

        recolor-self
      ]
    ]
  ]

  update-turtles
  update-globals
  reset-ticks
end 


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; MAIN LOOP
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

to go
  if not any? turtles [ stop ]
  if ticks > 5000 [ stop ]

  update-beliefs


  update-turtles


  move-unhappy-turtles


  update-turtles

  update-globals
  update-plot

  tick
end 


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; BELIEF UPDATING
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

to update-beliefs
  ask turtles [

    let nbr-patches (ifelse-value von-neumann?
                       [ neighbors4 ]
                       [ neighbors ])
    let nbrs turtles-on nbr-patches

      let social-influence 0
    if any? nbrs [
      set social-influence (count nbrs with [ believer? ]) / count nbrs
    ]


    let conv-prob  clamp01 (0.8 * social-influence
                             + 0.6 * logistic personal-faith
                             + missionary-rate)

    let deconv-prob clamp01 (dropout-rate
                             + 0.3 * (1 - social-influence))


    if random-float 1 < conv-prob [
      set believer? true
    ]

    if random-float 1 < deconv-prob [
      set believer? false
    ]

    recolor-self
  ]
end 


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; SATISFACTION & MOVEMENT
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

to update-turtles
  ask turtles [
    let nbr-patches (ifelse-value von-neumann?
                       [ neighbors4 ]
                       [ neighbors ])
    let nbrs turtles-on nbr-patches

    set similar-nearby count nbrs with [ believer? = [ believer? ] of myself ]
    set other-nearby   count nbrs with [ believer? != [ believer? ] of myself ]
    set total-nearby   similar-nearby + other-nearby

    if total-nearby = 0 [
      set happy? true
    ]
    if total-nearby > 0 [
      set happy? similar-nearby >= (%-similar-wanted * total-nearby / 100)
    ]


    if visualization = "old" [
      set shape "default"
      set size 1.3
    ]
    if visualization = "square-x" [
      ifelse happy?
        [ set shape "square" ]
        [ set shape "X" ]
      set size 1.3
    ]
  ]
end 

to move-unhappy-turtles
  ask turtles with [ not happy? ] [
    find-new-spot
  ]
end 

to find-new-spot
  rt random-float 360
  fd random-float 10
  if any? other turtles-here [ find-new-spot ]
  move-to patch-here
end 

to recolor-self

  if believer? [
    if type-id = 1 [ set color 105 ]
    if type-id = 2 [ set color 105 - 1 ]
    if type-id = 3 [ set color sky ]
    if type-id = 4 [ set color cyan ]
  ]
  if not believer? [
    if type-id = 1 [ set color 27 ]
    if type-id = 2 [ set color 27 + 1 ]
    if type-id = 3 [ set color 27 + 2 ]
    if type-id = 4 [ set color 27 + 3 ]
  ]
end 


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; GLOBAL METRICS & PLOT
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

to update-globals
  let total count turtles
  if total = 0 [
    set percent-believers 0
    set percent-similar 0
    set percent-unhappy 0
    stop
  ]


  set percent-believers 100 * (count turtles with [ believer? ]) / total


  let similar-neighbors sum [ similar-nearby ] of turtles
  let total-neighbors   sum [ total-nearby ] of turtles
  if total-neighbors > 0 [
    set percent-similar 100 * similar-neighbors / total-neighbors
  ]


  set percent-unhappy 100 * (count turtles with [ not happy? ]) / total
end 

to update-plot
  set-current-plot "Believer Share"
  set-plot-y-range 0 100
  set-current-plot-pen "share"
  plotxy ticks percent-believers
end 


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; UTILITY FUNCTIONS
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

to-report clamp01 [x]
  if x < 0 [ report 0 ]
  if x > 1 [ report 1 ]
  report x
end 

to-report logistic [x]
  report 1 / (1 + exp (- x))
end

There are 2 versions of this model.

		Uploaded by	When	Description	Download
		Junnan Lyu	2 days ago	New version of MARAS model	Download this version
		Junnan Lyu	3 days ago	Initial upload	Download this version

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