NetLogo: avoid to have too many beetles on one patch in one time step?

Question

I would like to implement certain rules into relationship between my turtles and my patches. My Patches variables are:

n_min - if there is enough turtles, change pcolor to pink, change yellow turtles on patch to orange
n_max - if there is too many turtles, set pcolor to brown, let all turtles to avoid this patch

My turtles states are: yellow (move) -> orange (stay) -> red (infest) Patches states are: green (n_min< then number of orange turtles on one patch) pink (number of orange turtles is > n_min and < n_max) brown (no turtles)

My problem is how can I avoid to have more then n_max turtles on one patch if they are all moving at the same time and thus are targeted to same patch? How can I include the condition that "if you see that there are some turtles of color orange/red, just keep moving to find another patch? " Also, if my patch is already pink, and n_min != n_max to ask turtles to directly change its color to red?

Thank you a lot !

my not working example:

globals [
  available-patch
]


patches-own [
  nmax   ; maximum nuber of turtles per patch, and change color
  nmin   ; minimum number of turtles to change patch color
  n.yellow  ; how many turtles are on the patch with yellow
  n.orange  ; how many orange (staying) turtles are on 1 patch?
]

to setup
  clear-all
  reset-ticks
  setup-patches
  setup-turtles
end

to setup-patches
  ask n-of n_patches patches [
    set pcolor green
    set nmin n_min     ; how many orange turtles can be there to set the patch to pink? 
    set nmax n_max     ; max number of orange beetles to turn the patch to brown
  ]
end

to setup-turtles
  crt n_turtles [
    set color yellow
  ]
end

to go
  tick
  ask turtles with [color = yellow ] [   ; move only yellow turtles
    move-turtles
  ]
  ask patches [  ; if n.orange = nmin, turn all turtles to red and turn patch to pink
    set n.orange count turtles-here with [color = orange]
  ] 
end

to move-turtles
   ;  if color = yellow ;and n.yellow < nmin 
   ;ifelse count other turtles-on
;   move-to one-of patches with [pcolor = green and n.orange <= nmin]
;   if [n.orange <= nmin] of patch-here [
;     set color orange  ; not to move anymore. However, the n.orange should be always less then nmin !!
;   ]
   set available-patch patches with [pcolor = green and count turtles-here with [color = orange] < 2] ; agentset 
   ifelse (count other turtles-on available-patch <= nmin) ; how to change the code for nmin here?
     [ move-to one-of available-patch                         
       set color orange
       ask patch-here [
         set n.orange count turtles-here with [color = orange]
       ]
     ]
     [ fd 2 ]


end

Result:

one turtle on the green patch has changed its color to orange, but I wanted 2 turtles (nmin) to find green patch and become orange. Also, the yellow turtles move next time steps just by [fd 2], the "ifelse" condition is not re-run each time step.

Have you looked at One Turtle Per Patch Example, in the Code Examples section of the Models Library? If you understand well how that code works, then generalizing it to "n turtles per patch" probably won't be too hard. — Seth Tisue
Hi @SethTisue thanks for advice. I included my modified question, because I think I can't correctly insert the nmin and nmax values per patch - in this code I have only one turtle per patch, but I want to have there 2 of them (nmin = 2) but is doesn't work.. Please, how can I fixed this condition? Thank you again ! — maycca

Seth Tisue Seth Tisue · Accepted Answer · 2015-10-05T12:32:26

First, a specific piece of advice:

You've given available-patch a singular-sounding name, but it's actually plural: it's a patchset of all patches satisfying the condition you've set.

Then when you write:

count other turtles-on available-patch <= nmin

available-patch is actually many patches, count turtles-on available-patch is summing all of the turtle counts on all of those patches. This doesn't make any sense.

Perhaps you meant:

set available-patch one-of patches with ...

OK, so that's one bug in your code, but I don't think it's the only one. I have a more general piece of advice: you are trying to write much too much code all at once. This is a recipe for flailing. You should try to write a much simpler model first, with simpler rules, and get it working. Once it's working, make it a little more complex by adding another rule, get that working, and so forth. Work your way up towards the full model step by step. If at any point you get stuck, ask a question here on Stack Overflow. You'll have a good, specific question to ask, instead of your current situation where your question seems to be "here is a bunch of code that isn't anywhere close to working, help!".

P.S. unrelated to your problem, but reset-ticks always goes at the end of setup, never near the beginning. tick always goes at the end of go, never near the beginning.

NetLogo: avoid to have too many beetles on one patch in one time step?

2 Answers