Flocking Benchmark

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Uri_dolphin3 Uri Wilensky (Author)

Tags

biology 

Tagged by Reuven M. Lerner about 7 years ago

Model group CCL | Visible to everyone | Changeable by group members (CCL)
Model was written in NetLogo 4.1pre9 • Viewed 239 times • Downloaded 28 times • Run 1 time
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globals [
  result
]

turtles-own [
  flockmates         ;; agentset of nearby turtles
  nearest-neighbor   ;; closest one of our flockmates
]

to benchmark
  random-seed 5454
  reset-timer
  setup
  repeat 700 [ go ]
  set result timer
end 

to setup
  ca
  cro population
    [ set color yellow - 2 + random 7  ;; random shades look nice
      setxy (random-float world-width)
            (random-float world-height)
      rt random-float 360 ]
end 

to go
  ask turtles [ flock ]
  tick
end 

to flock  ;; turtle procedure
  find-flockmates
  if any? flockmates
    [ find-nearest-neighbor
      ifelse distance nearest-neighbor < minimum-separation
        [ separate ]
        [ align
          cohere ] ]
  fd 1
end 

to find-flockmates  ;; turtle procedure
  set flockmates other turtles in-radius vision
end 

to find-nearest-neighbor ;; turtle procedure
  set nearest-neighbor min-one-of flockmates [distance myself]
end 

;;; SEPARATE

to separate  ;; turtle procedure
  turn-away ([heading] of nearest-neighbor) max-separate-turn
end 

;;; ALIGN

to align  ;; turtle procedure
  turn-towards average-flockmate-heading max-align-turn
end 

to-report average-flockmate-heading  ;; turtle procedure
  ;; We can't just average the heading variables here.
  ;; For example, the average of 1 and 359 should be 0,
  ;; not 180.  So we have to use trigonometry.
  report atan mean [sin heading] of flockmates
              mean [cos heading] of flockmates
end 

;;; COHERE

to cohere  ;; turtle procedure
  turn-towards average-heading-towards-flockmates max-cohere-turn
end 

to-report average-heading-towards-flockmates  ;; turtle procedure
  ;; "towards myself" gives us the heading from the other turtle
  ;; to me, but we want the heading from me to the other turtle,
  ;; so we add 180
  report atan mean [sin (towards myself + 180)] of flockmates
              mean [cos (towards myself + 180)] of flockmates
end 

;;; HELPER PROCEDURES

to turn-towards [new-heading max-turn]  ;; turtle procedure
  turn-at-most (my-subtract-headings new-heading heading) max-turn
end 

to turn-away [new-heading max-turn]  ;; turtle procedure
  turn-at-most (my-subtract-headings heading new-heading) max-turn
end 

;; turn right by "turn" degrees (or left if "turn" is negative),
;; but never turn more than "max-turn" degrees

to turn-at-most [turn max-turn]  ;; turtle procedure
  ifelse abs turn > max-turn
    [ ifelse turn > 0
        [ rt max-turn ]
        [ lt max-turn ] ]
    [ rt turn ]
end 

;; To find the difference between two headings, we can't just
;; subtract the numbers, because 0 and 360 are the same heading.
;; For example, the difference between a heading of 5 degrees
;; and a heading of 355 degrees is 10 degrees, not 350 degrees.

to-report my-subtract-headings [h1 h2]
  ifelse abs (h1 - h2) <= 180
    [ report h1 - h2 ]
    [ ifelse h1 > h2
        [ report h1 - h2 - 360 ]
        [ report h1 - h2 + 360 ] ]
end 

There are 3 versions of this model.

Uploaded by When Description Download
Uri Wilensky about 10 years ago Updated from NetLogo 4.1 Download this version
Uri Wilensky about 10 years ago Flocking Benchmark Download this version
Uri Wilensky about 10 years ago Flocking Benchmark Download this version

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