联盟形成模型运行报错求助：THREATS breed未定义ACTIVE?变量

Let's break down what's causing this error and fix it step by step, along with some other tweaks to make your model run smoothly:

Root Cause of the Error #

The error pops up because your update-turtles procedure uses ask turtles—which includes both agents and threats—but the active? variable is only defined in agents-own. When NetLogo tries to access active? on a threat turtle, it throws an error because threats don't have that variable assigned to them.

Step-by-Step Fixes #

1. Restrict Agent-Specific Logic to agents Only #

Change all instances where you're asking turtles to instead target agents when dealing with variables like active?, allied-states, etc.:

• In go: Replace if all? turtles [ active? ] [ stop ] with if all? agents [ active? ] [ stop ]
• In move-unhappy-turtles: Replace ask turtles with [ not active? ] [ find-new-spot ] with ask agents with [ not active? ] [ find-new-spot ]
• In update-turtles: Replace ask turtles [ ... ] with ask agents [ ... ]

2. Fix Global Variable Calculations in update-globals #

Globals like percent-similar and percent-unhappy should only calculate values from agents, not all turtles. We also add a check to avoid division by zero:

let similar-neighbors sum [ allied-states ] of agents
let total-neighbors sum [ total-nearby ] of agents
set percent-similar (similar-neighbors / max (list 1 total-neighbors)) * 100
set percent-unhappy (count agents with [ not active? ]) / max (list 1 count agents) * 100

3. Correct allied-states and perceived-threat to Be Proportions #

Your variable comments note these should be 0-1 proportions, but your original code uses raw counts. Update the calculation to get ratios (and exclude threats from neighbor counts):

let same-color-neighbors count (agents-on neighbors) with [ color = [ color ] of myself ]
let diff-color-neighbors count (agents-on neighbors) with [ color != [ color ] of myself ]
set total-nearby same-color-neighbors + diff-color-neighbors
set allied-states same-color-neighbors / max (list 1 total-nearby)
set perceived-threat diff-color-neighbors / max (list 1 total-nearby)

4. Improve the find-new-spot Procedure #

The original recursive logic can cause stack overflow if empty spots are hard to find. Replace it with a more efficient approach:

to find-new-spot
  let empty-patches patches with [ not any? turtles-here ]
  if any? empty-patches [
    move-to one-of empty-patches
  ]
end

5. Add Missing Global Variables #

Your setup procedure references variables like vision and initial-threats-density that weren't declared. I've added these to the globals list—you'll need to create corresponding sliders in your NetLogo interface for them.

Full Corrected Code #

breed [ agents an-agent]
breed [ threats threat ]
globals [ k ; 攻击概率决定因子
          threshold ; 状态分担阈值：D - BS 需比 A 大多少才满足条件
          percent-similar ; 平均相似度：海龟邻居中与自身颜色相同的比例，影响结盟倾向
          percent-unhappy ; 不满比例：处于不满或感知到威胁的海龟占比
          visualization
          vision ; Add missing vision global
          initial-threats-density ; Add missing setup globals
          initial-agent-density
          movement?
          alliance-protection
          conflict-term ]

agents-own [ allied-states ; R，智能体生命周期内固定，取值0-1（含），表示海龟邻居中颜色相同的比例是否达到期望相似度
            perceived-threat ; T，取值0-1（含），表示颜色不同的邻居海龟数量占比
            active? ; 若为true，智能体处于活跃结盟状态；若为false，智能体搭便车
            conflict ; 剩余冲突回合数（为0时无冲突）
            total-nearby ; 邻近海龟总数（allied-states与perceived-threat之和） ]

patches-own [ neighborhood ; 视野半径内的周边斑块 ]

to setup
  clear-all
  ; 设置全局变量（adjust these values or add sliders in the interface）
  set k 2.3
  set threshold 0.1
  set vision 5
  set initial-threats-density 10
  set initial-agent-density 40
  set movement? true
  set alliance-protection 0.5
  set conflict-term 5
  set visualization "square-x"

  ask patches [
    ; 将背景设为深灰色
    set pcolor gray - 1
    ; 缓存斑块周边区域
    set neighborhood patches in-radius vision
  ]

  if initial-threats-density + initial-agent-density > 206 [
    user-message (word "The sum of INITIAL-THREATS-DENSITY and INITIAL-AGENT-DENSITY " "should not be greater than 206.")
    stop
  ]

  ; 创建威胁智能体
  create-threats round (initial-threats-density * .01 * count patches) [
    move-to one-of patches with [ not any? turtles-here ]
    display-threats
  ]

  ; 创建智能体
  create-agents round (initial-agent-density * .01 * count patches) [
    move-to one-of patches with [ not any? turtles-here ]
    set heading 0
    set allied-states random-float 1.0
    set perceived-threat random-float 1.0
    set active? false
    set conflict 0
    display-agent
  ]

  ; 重置时钟并绘制系统初始状态
  reset-ticks
end

to go
  if all? agents [ active? ] [ stop ]
  move-unhappy-turtles
  update-turtles
  update-globals
end

; 不满的海龟尝试迁移到新位置
to move-unhappy-turtles
  ask agents with [ not active? ] [ find-new-spot ]
end

; 移动至未被占据的斑块
to find-new-spot
  let empty-patches patches with [ not any? turtles-here ]
  if any? empty-patches [
    move-to one-of empty-patches
  ]
end

to update-turtles
  ask agents [
    ; 计算同色和异色邻居的比例
    let same-color-neighbors count (agents-on neighbors) with [ color = [ color ] of myself ]
    let diff-color-neighbors count (agents-on neighbors) with [ color != [ color ] of myself ]
    set total-nearby same-color-neighbors + diff-color-neighbors
    set allied-states same-color-neighbors / max (list 1 total-nearby)
    set perceived-threat diff-color-neighbors / max (list 1 total-nearby)
    
    ; 更新活跃状态（调整逻辑匹配比例尺度）
    set active? allied-states >= (percent-similar / 100)

    ; 添加可视化设置
    if visualization = "old" [
      set shape "default"
      set size 1.3
    ]
    if visualization = "square-x" [
      ifelse active? [ set shape "square" ] [ set shape "X" ]
    ]
  ]
end

to update-globals
  let similar-neighbors sum [ allied-states ] of agents
  let total-neighbors sum [ total-nearby ] of agents
  set percent-similar (similar-neighbors / max (list 1 total-neighbors)) * 100
  set percent-unhappy (count agents with [ not active? ]) / max (list 1 count agents) * 100

  ; 处于冲突中的智能体每回合减少冲突剩余回合数
  ask agents [
    if conflict > 0 [ set conflict conflict - 1 ]
  ]

  ; 更新智能体显示
  ask agents [ display-agent ]
  ask threats [ display-threats ]

  tick
end

; 智能体与威胁智能体行为
; 移动至空斑块
to move ; 海龟过程
  if movement? or breed = threats [
    ; 移动至视野内的斑块；候选斑块为空或仅包含处于冲突中的智能体
    let targets neighborhood with [ not any? threats-here and all? agents-here [ conflict > 0 ] ]
    if any? targets [ move-to one-of targets ]
  ]
end

; 智能体行为
to determine-behavior
  set active? (burden-sharing - allied-states * estimated-conflict-probability > threshold)
end

to-report burden-sharing
  report perceived-threat * (1 - alliance-protection)
end

to-report estimated-conflict-probability
  let t count (threats-on neighborhood)
  let a 1 + count (agents-on neighborhood) with [ active? ]
  ; 有关以下公式的讨论请查看Info标签页
  report 1 - exp (- k * floor (t / a))
end

to alliance
  if any? threats [attack]
  set active? true
end

; 威胁智能体行为
to attack
  if any? (agents-on neighborhood) with [ active? ] [
    ; 逮捕目标
    let suspect one-of (agents-on neighborhood) with [ active? ]
    move-to suspect
    ; 移动至被逮捕智能体的斑块
    ask suspect [
      set active? false
      set conflict random conflict-term
      set color pink
    ]
  ]
end

; 智能体与威胁智能体可视化
to display-agent ; 智能体过程
  if conflict > 0 [
    set color pink
  ] else [
    set color cyan
  ]
  set shape "triangle"
end

to display-active?
  set color pink
  set shape "triangle"
end

to display-threats
  set color red
  set shape "circle 2"
end

Quick Additional Notes #

• I adjusted the display-agent procedure to check for active conflicts and set the pink color automatically, which aligns with your attack logic.
• The active? calculation was updated to match the 0-1 proportional scale of allied-states.

内容的提问来源于stack exchange，提问作者Cfitzg