turtles-own [message? other-turtle]

to setup
  ca
  cct 200 [
    set message? false
    setxy random-float screen-size-x
          random-float screen-size-y
  ]
  set message?-of random-one-of turtles true      ; give the message to one of the turtles
  ask turtles [
    color-turtles                                 ; color the turtles red if they have the message, blue otherwise
  ]
end

to go
  every 0.1 [
    ask turtles [move]
    ask turtles [                                    ;;when they're all done moving, start a new "ask turtles"
     communicate
     color-turtles  
    ]
  ]
end

; move randomly
to move  ;a turtle procedure
  fd random 4
  ; turn a random amount between -40 and 40 degrees,
  ; keeping the average turn at 0
  rt random-float 40
  lt random-float 40
end

; the core procedure!
to communicate ;;a turtle procedure
  set other-turtle random-one-of other-turtles-here  ; get the ID of another turtle on your patch
  if(other-turtle != nobody)                              ; if there is one there
    [if message?-of other-turtle                     ; (only IDs of 0 and above are valid)
      [set message? true]                            ; if the other turtle has the message
    ]                                                ; get the message
end

; color turtles with message red, and those without message blue
to color-turtles  ; a turtle procedure
  ifelse message?
    [set color red]
    [set color blue]
end
@#$#@#$#@
GRAPHICS-WINDOW
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CC-WINDOW
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Command Center

BUTTON
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76
43
NIL
setup
NIL
1
T
OBSERVER

BUTTON
92
10
147
43
NIL
go
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T
OBSERVER

BUTTON
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setup
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OBSERVER

BUTTON
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147
43
NIL
go
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1
T
OBSERVER

MONITOR
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229
116
NIL
count turtles with [color = red]
3
1

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WHAT IS IT?
-----------
This code example is a simple demo of turtle-turtle communications. One turtle starts out with a message (the red turtle) and she spreads the message to other turtles.

The monitor keeps track of how many turtles have the message by reporting:
  count turtles with [color = red]

Note that if you put a procedure inside an "ask turtles [  ]" bracket, then everything in that procedure will be executed by all of the turtles.
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NetLogo 2.0alpha1
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