Contraception Simulation R0

;;
;; Global variables.
;;
globals [count_OS0 delta_OS0 EAVG E1up]

;;
;; turtle/breed.
;;

;;
;; turtle/breed variables.
;;
turtles-own [
  MS  ;; mental state, MS = 1 if the agent tends to use correctly the tool, 0 otherwise
  OS  ;; observed state, OS = 1 if the tool has always been used correctly, 0 otherwise.
]

;;
;; setup.
;;

to setup
  clear-all
  reset-ticks
  setup-world
  setup-turtles
  ;; etc
end 

;;
;; setup-world.
;;

to setup-world
  ask patches [ set pcolor green + 2]
end 

;;
;; setup-turtles.
;;

to setup-turtles
  ;; Initialize global variables.

  ;; Create the turtles and set their initial states.
  create-turtles number_agents
  [ set shape "person"
    setxy random-xcor random-ycor]

  ;; Initial MS and OS.
  ask turtles
  [
    ifelse random 100 < S1
    [ set MS 1
      set color 9.9]
    [ set MS 0
      set color 0  ]
    set OS 1
  ]
  ;; Update counts.
  update-counts

set EAVG (S1 * E1 + (100 - S1) * E0) / 100
set delta_OS0 0
set E1up E1
end 

;;
;; go.
;;

to go
  ;; Criteria to stop.
  if (ticks > number_ticks) [stop]
  if (count_OS0 = number_agents) [stop]

  ;; Otherwise do-things.

  ;; Update status.
  update-turtles

  ;; Update counts.
  update-counts

  ;; tick.
  tick
end 

;;
;; update-turtles.
;;

to update-turtles
  ask turtles
  [ ;; update MS with LR0
    if MS = 0
    [
      if random 100 <= LR0
      [ set MS 1
        if OS = 0 [set color 25]
        if OS = 1 [set color 9.9]
      ]
    ]

    ;; update OS
    set E1up E1up * (100 - LR1) / 100
    if OS = 1
    [
      ifelse MS = 0
      [ if random 100 <= E0
        [set OS 0
        set color 15]
      ]
      [ if random 100 <= E1up
        [set OS 0
        set color 25]
      ]
    ]
  ]
end 

to update-counts
  ;; Update counts.
  set delta_OS0 count turtles with [OS = 0] - count_OS0
  set count_OS0 count turtles with [OS = 0]
end