NetLogo中如何让每个Patch识别自身颜色并统计同色Patch数量？

Got it, let's break down why your original code isn't working and fix it step by step.

The Problem with Your Original Code #

Your line ask patches [count patches with pcolor = [pcolor] of myself] fails because of scope confusion in NetLogo. When you use myself inside the with block, it doesn’t refer to the patch running the ask command—instead, it points to the patch that with is currently checking. So effectively, you’re asking each patch to count all patches where their color equals their own color... which is every single patch, not just those matching the original patch’s color.

The Simple Fix: Use a Local Variable #

The solution is to store the current patch’s color in a local variable first, so the with block can reference that fixed value instead of getting mixed up about scope. Here’s the corrected code:

ask patches [
  ; Store the current patch's color in a local variable
  let my-color pcolor
  ; Count all patches that match this stored color
  let same-color-count count patches with [pcolor = my-color]
  ; Optional: Print or use the count (example below)
  print (word "Patch at (" pxcor "," pycor ") has " same-color-count " matching color patches")
]

This works because my-color is tied directly to the patch running the ask command. When the with block checks each patch, it compares their color to the original patch’s stored color, not their own.

Optimize for Large Worlds (Optional) #

If you’re working with a big grid of patches, the above code will run slowly because every patch has to loop through all patches to count matches. A better approach is to precompute the count for each color once, then let each patch look up that value:

; Step 1: Create a table to map each color to its total count
let color-counts table:make
ask patches [
  let current-color pcolor
  ifelse table:has-key? color-counts current-color
    [ table:put color-counts current-color (table:get color-counts current-color + 1) ]
    [ table:put color-counts current-color 1 ]
]

; Step 2: Have each patch look up its color's count
ask patches [
  let same-color-count table:get color-counts pcolor
  print (word "Patch at (" pxcor "," pycor ") has " same-color-count " matching color patches")
]

This only loops through all patches once to build the count table, making it much faster for large simulations.

内容的提问来源于stack exchange，提问作者Ask8