NetLogo代码报错：行26、32持续提示Expected command，求助解决

错误根源与解决办法 #

• HTML转义引号干扰语法解析：代码中所有"是HTML转义字符，NetLogo无法识别，必须替换为普通双引号"。比如将set-default-shape signals "circle"改为set-default-shape signals "circle"，所有字符串引号都要同步修正。
• 海龟上下文错误调用补丁命令：signals是海龟，直接调用neighbors4会获取相邻海龟，而sprout-signals是补丁专属命令，不能在海龟对象上执行。需改为ask [neighbors4] of patch-here with [is-mycelium? and pcolor = green]，明确操作的是当前海龟所在补丁的四邻补丁。
• 全局变量未初始化：mycelium-density、native-percentage、drought?未设置初始值，若未在NetLogo界面添加对应滑块/开关，需在setup开头手动初始化（修复代码中已添加判断逻辑）。

修复后完整代码 #

globals [
  mycelium-density
  native-percentage
  drought?
  initial-mycelia
  signal-passed
]

breed [signals signal]
breed [fades fade]

patches-own [
  plant-species
  is-mycelium?
]

to setup
  clear-all
  set-default-shape signals "circle"

  ; 初始化全局变量（避免未设置界面元素时出错）
  if not is-defined? mycelium-density [ set mycelium-density 30 ]
  if not is-defined? native-percentage [ set native-percentage 50 ]
  if not is-defined? drought? [ set drought? false ]

  if drought? [ 
    set mycelium-density mycelium-density * 0.5
  ]
  
  ask patches [
    if random-float 100 < mycelium-density [
      set pcolor green
      set is-mycelium? true
    ] [
      set pcolor brown
      set is-mycelium? false
    ]
    
    if random-float 100 < native-percentage [
      set plant-species "native"
    ] [
      set plant-species "non-native"
    ]
  ]
  
  ask patches with [pxcor = min-pxcor and is-mycelium?] [
    sprout-signals 1 [ set color blue ]
  ]
  
  set initial-mycelia count patches with [is-mycelium?]
  set signal-passed 0
  reset-ticks
end

to go
  if not any? signals [ stop ]
  
  ask signals [
    ; 修正：操作当前海龟所在补丁的四邻补丁
    ask [neighbors4] of patch-here with [is-mycelium? and pcolor = green] [
      sprout-signals 1 [ set color blue ]
      set pcolor black
    ]
    set breed fades
  ]
  
  ask fades [
    set color color - 1
    if color < blue - 10 [
      ; 修正：恢复补丁的菌丝颜色
      set pcolor green
      die
    ]
  ]
  
  tick
end

内容的提问来源于stack exchange，提问作者Eduardo Dorado