ch1-abma-dispersal.nlogo

extensions [import-a fetch]
;;; SETUP PROCEDURE

to setup
  clear-all
  let thing (fetch:url (word "https://raw.githubusercontent.com/SantaFeInstitute/ABMA/master/ch1/ch1_map.png"))
  import-a:pcolors thing
  create-turtles 20                        ; create 20 agents
  [                                        ; with the following state variables:
    set color random 140                   ; color
    set size 2                             ; size
    set shape "turtle"                     ; shape
    ; setxy random 5 random 5              ; location
    setxy ( 360 + random 5 ) ( 170 + random 5 )
  ]
  reset-ticks
end

to go
; at each time step turtles reproduce with a probability equal to the pop_growth (slider)
  ask turtles [
    ;rt random 360                         ; this is previous code used to move turtles around
    ;fd 1
    if random-float 1 <= pop_growth        ; this version is driven by population growth (slider)
       [ reproduce ]                       ; the reproduction procedure is defined below
  ]

  tick
end

to reproduce
  ; turtles reproduce only if there is an unoccupied patch in their surrounding that is not water
  if any? neighbors4 with [count turtles-here = 0 AND pcolor != white] [
    let empty-patch one-of neighbors4 with [count turtles-here = 0 AND pcolor != white]
    hatch 1 [
      set color color + 0.1                 ; new turtles are clones of parents but we change the color a bit
      move-to empty-patch                   ; move the newly hatched turtle to a new patch
    ]
  ]
end