Single Club-Type Model

breed [anchors anchor]
breed [people person]
breed [clubs club]

globals [
  center-anchor
  goals-met
  goals-missed
  mean-age
]

people-own [
  income  ;; monthly income
  goal-size  ;; how much money a turtle would like to accumulate
  goal-time  ;; how long a turtle has to accumulate the money
  goal-time-unrounded
  contribution ;; how much the turtle will contribute this tick
  accomplished-goal? ;; when club has finished its rounds, true if this turtle has met its savings goal
]

clubs-own [
  monthly-contribution  ;; how much individuals put in monthly
  members  ;; how many members are in the group
  money  ;; how much money is in the pot
  desired-members  ;; how many members the group can hold
  status ;; whether the club is full or not full
  ticks-at-start ;; value of tick counter when club started saving
  lifespan
]

to setup
  ca
  ; Create the center node anchor
    create-anchors 1 [
      set shape "circle"
      set color black
    ]
   ; This is a convenience variable that points to the center anchor
    set center-anchor one-of anchors
  create-people population
  set-default-shape people "person"
  set-default-shape clubs "circle"
  ask people [
    setxy random-xcor random-ycor
    set income random-normal mean-income income-variance 
    set goal-size random-normal mean-goal-size 10
    set goal-time-unrounded random-normal mean-goal-time goal-time-variance
    set goal-time round goal-time-unrounded
    if goal-time = 0 [
      die]
    set contribution 0
  ] 
 set goals-met 0
 set goals-missed 0
end 

to go
  ;; someone who is not currently in a club creates a club
  make-club
  ;; if there are any open clubs, someone who is not in a closed club decides whether or not to join one. Five people are asked this.
  ask people [ maybe-join]
  ;; if a club has been abandoned, it disappears
  ask clubs [
    if count my-links = 0 [
      die 
     ]
    ] 
   ;; visualization
    ask clubs [
      repeat 30 [
      layout-spring link-neighbors my-links .2 2 .5
      ]
     ]
    layout-spring clubs ( [my-links] of center-anchor ) .2 14 .5     
  tick  
  ;; if a club is full, run saving procedures
  ask clubs[
    if status = "full" [
     save
    ] 
  ]
  set mean-age mean [ticks - ticks-at-start] of clubs with [status = "full"]
  update-plots   
end 

;; a person who is not in a club creates a club

to make-club 
  if any? people with [count my-links = 0] [
    ask one-of people with [count my-links = 0] [
      create-saving-up] 
  ]
end 

to create-saving-up 
  ;; a club is created 2 spaces north of its creator, colored yellow
  ask patch-here [
    let creator myself
    sprout-clubs 1 [
      ifelse [ycor] of creator <= 14 
      [
        setxy [xcor] of creator [ycor] of creator + 2]
      [
        setxy [xcor] of creator [ycor] of creator - 2]
      set color yellow
      set size 1.3
      set lifespan " "
      ;; set monthly contribution such that expected payout in goal-time months = goal-size
      set monthly-contribution [goal-size] of creator / ([goal-time] of creator * (1 - risk))
      ;; the club's desired membership is its creator's goal-time rounded up 
      set desired-members [ceiling goal-time] of creator
      ;; initially, the club is not full
      set status "not-full"
      ;; the creator becomes the club's first member
      create-link-with creator
    ]
  ]
end 

to maybe-join 
  ask clubs [
    set members count my-links  ;; update members variable
    if members = desired-members 
    [
      set status "full"]
  ]
  if any? clubs with  [status = "not-full" ]  ;; if any open clubs remain
  [
    let open-club one-of clubs with [status = "not-full"]  ;; choose an open club to look at
    ;; if there is a person not already in a closed club, whose characteristics match this open club, join it (create link, kill other links)
    
    if any? people with [ count link-neighbors with [status = "full"] = 0 and 
                             (([desired-members] of open-club) * ([monthly-contribution] of open-club) * (1 - risk) >= goal-size) and 
                             ([desired-members] of open-club >= goal-time) ] 
    [
       ask one-of people with [ count link-neighbors with [status = "full"] = 0 and 
                             (([desired-members] of open-club) * ([monthly-contribution] of open-club) * (1 - risk) >= goal-size) and 
                             ([desired-members] of open-club >= goal-time) ] 
      [
       ask my-links 
       [
        die]
       create-link-with open-club
    ]
      ]                         
    ask open-club 
    [
     set members count my-links  ;; update members variable
     if members = desired-members 
     [
      set status "full"
      set ticks-at-start ticks]  
    ]
  ]
end 

to save
    ;; each member contributes 0 "risk"% of the time and "monthly-contribution" (1-"risk")% of the time
      ask link-neighbors [
        ifelse random-float 1 < risk 
        [
          set contribution 0]
        [
          set contribution [monthly-contribution] of myself]
      ]
    ;; money in the club increases by the amount of its members contributions
    set money money + sum [contribution] of link-neighbors
    ;; visually show money in club
    set label round money 
    set label-color black
    ;; when there have been as many ticks as there are members, divide up the money 
    if (ticks - ticks-at-start) mod members = 0 and (ticks != ticks-at-start) 
    [
     split-prize]
end 

to split-prize
  ;; set prize equal to money in the club divided by number of members
  let prize (money / members)
  ;; if the prize is >= goal size, goal is accomplished and stay in the club
  ;;if the prize is < goal size, goal is not accomplished and leave the club
  ask link-neighbors [
   ifelse [prize] of myself >= goal-size 
   [
    set accomplished-goal? true
    set goals-met goals-met + 1] 
   [
    set accomplished-goal? false
    set goals-missed goals-missed + 1
    ask my-links
    [
     die]
    ]]
  set members count my-links
  if members < desired-members 
  [
   set status "not-full" ]
   set money 0
   set label " " 
end 

to update-plots
  set-current-plot "plot 1"
  set-current-plot-pen "#-closed-clubs"
  plot count clubs with [status = "full"]
  set-current-plot-pen "mean-age"
  plot mean-age
  set-current-plot-pen "mean-size"
  plot mean [members] of clubs with [status = "full"]
  set-current-plot "plot 2"
  set-current-plot-pen "goals-met"
  plot goals-met
  set-current-plot-pen "goals-missed"
  plot goals-missed
end