Simple SIR (static)

turtles-own
[sick?
 recovered?
 susceptible?
 sick-time
]

globals
[ %infected
  %recovered
  %susceptible
]

to setup
  clear-all
  setup-turtles
  update-global-variables
  ;update-display
  reset-ticks
end 

to setup-turtles
  create-turtles number-people
  [setxy random-xcor random-ycor
    set shape "person"
    set size 1.5
    set sick-time 0
    set sick? 0
    set recovered? 0
    set susceptible? 1
    set color green]
  ask n-of 2 turtles
  [set sick? 1
    set susceptible? 0
  set color red]
end 

to go
  ask turtles [
    move
    age
    if sick? = 1 [recover]
    if sick? = 1 [infect]
  ]
  update-global-variables
  ;update-display
  tick
end 

to update-global-variables
  if count turtles > 0
  [set %infected (count turtles with [sick? = 1] / count turtles) * 100
   set %recovered (count turtles with [recovered? = 1] / count turtles) * 100
    set %susceptible (count turtles with [susceptible? = 1] / count turtles) * 100
  ]
end 

;to update-display
  ;ask turtles
  ;[if shape != turtle-shape [set shape turtle-shape]
  ; ifelse sick? = 1 [set color red] [ifelse recovered? = 1 [set color grey][set color green]]]
;end

to move
  rt random 100
  lt random 100
  fd 1
end 

to infect
  ask other turtles-here with [sick? = 0 and recovered? = 0]
  [if random-float 100 < infectiousness
    [set sick? 1
      set susceptible? 0
  set color red]]
end 

to age
  ask turtles with [sick? = 1]
  [set sick-time sick-time + 1]
end 

to recover
  if sick-time > (duration * 100)
  [if random-float 100 < 100
    [set recovered? 1
    set sick? 0
    set susceptible? 0
    set color grey]
  ]
end