NetLogo双绘图异常及‘空列表均值’报错排查求助

问题现状 #

复刻NetLogo模型库「Lottery」示例的两个绘图时，X轴正常但Y轴功能失效：

• TURTLES PLOT：目标绘制每周海龟数量，仅计数器变动但绘图始终显示0
• PATCHES PLOT：目标绘制每周补丁平均花朵数，运行触发报错：Runtime error: Can’t find the mean of list with no numbers []

尝试将计数、平均值转为独立变量时，出现agentset类型错误，同类方案未解决问题。

问题代码 #

TURTLES PLOT 更新代码 #

clear-plot foreach sort remove-duplicates [week] of turtles 
    [ week-count -> plotxy week-count count turtles
                                       with [week-count = [week] of turtles]
      ]

PATCHES PLOT 更新代码 #

clear-plot foreach sort remove-duplicates [week] of turtles
    [ week-count -> plotxy week-count mean [flowers] of patches
                                                   with [week-count = [week] of turtles ]
      ]

补丁初始化代码 #

to setup-patches 
   ask patches 
       [    if random-float 100 < flower-density 
            [  set flowers 100
               set pcolor 134
               if flowers = 0
               [ while [ flowers = 0 ]
                       [ set flowers random-float 100 ]
                 ]
               ]
            ] 
end

问题排查与修复 #

1. TURTLES PLOT 错误修复 #

错误原因：[week] of turtles返回所有海龟的week列表，而非当前海龟的week值，导致with筛选条件逻辑完全错误，始终返回空集合，计数为0。

修复后代码：

clear-plot
foreach sort remove-duplicates [week] of turtles [
  week-count ->
    plotxy week-count count turtles with [week = week-count]
]

2. PATCHES PLOT 错误修复 #

错误原因：补丁没有week变量，patches with [week-count = [week] of turtles]会筛选出空集合，触发mean函数报错；同时逻辑上未正确关联补丁与对应周的海龟。

分场景修复：

• 如果补丁有对应周的week变量（需全局同步更新）：

clear-plot
foreach sort remove-duplicates [week] of turtles [
  week-count ->
    plotxy week-count mean [flowers] of patches with [week = week-count]
]

• 如果补丁无week变量，需统计当前周内被海龟访问过的补丁：

clear-plot
foreach sort remove-duplicates [week] of turtles [
  week-count ->
    let current-turtles turtles with [week = week-count]
    let target-patches patches with [any? turtles-here and member? self [patch-here] of current-turtles]
    plotxy week-count ifelse-value empty? target-patches [0] [mean [flowers] of target-patches]
]

3. 补丁初始化代码优化 #

原代码中if flowers = 0判断冗余（刚设置flowers 100不可能为0），优化后更简洁：

to setup-patches 
  ask patches [
    if random-float 100 < flower-density [
      set flowers random-float 100
      set pcolor 134
    ] else [
      set flowers 0
    ]
  ]
end

内容的提问来源于stack exchange，提问作者remcin