try

breed [trackers tracker]
breed [people person]
patches-own [
  road
  density
]
globals[
  tx
  ty
]

to startup
  ;; read the elevations from an external file
  ;; note that the file is formatted as a list
  ;; so we only have to read once into a local variable.
  file-open "try.txt"
  let patch-roads file-read
  file-close

  ;; transfer the data from the file into the sorted patches
  (foreach sort patches patch-roads [ [the-patch the-road] ->
    ask the-patch [ set road the-road ]
  ])
  set-default-shape turtles "circle"
  setup
end 

to setup
  clear-drawing
  clear-turtles
  create-trackers 1 [ setxy -71 96       ;;lxxx
                    set color green
                    set size 4]  ;;lxxx

  create-people 1 [ setxy -21 -25       ;;lxxx
                    set color red
                    set size 4]  ;;lxxx
  ask patches with [ road = 1] [set pcolor white
  ;;set people count turtles in-radius 30
    ;;set dist distance turtle 0

  ]

  reset-ticks
end 

to goonce
  ask patches[
   set density count people in-radius 5
   ;;set pcolor density
  ]
   ask trackers[
    let target max-one-of patches in-radius 10 [density]
    face target
    if any? people-here [  ;; if there are sheep here then eat one
      ask one-of people-here
         [die]
     ]
    fd 1
  ]
end 

to go
  ask patches with [pcolor =  white]
  [ set density count people in-radius 5]

     ask trackers[
    let target max-one-of patches in-radius 10 [density]
    face target
    if any? people-here [  ;; if there are sheep here then eat one
      ask one-of people-here
         [die]
     ]
    fd 1
  ]




 ; ask turtle 0 [
   ;; move-to one-of neighbors4 with [pcolor = white]
    ;;ask turtles [ show max-one-of turtles [distance myself] ]
   ;; let p max-one-of neighbors [patch-variable]
    ;;if [patch-variable] of p > patch-variable [
    ;;face p
;;move-to p
;;]
    ;; uphill patch-variable uphill4 patch-variable
 ;   move-to one-of neighbors4  with [pcolor = white]

 ; ]
end