Netlogo：没有定义任何命名的边缘

Question

我是 netlogo 的新手（版本：6.1.1）。我只是想创建一个围绕原点的补丁。但它提醒我“没有定义任何名为边缘的东西。”

to setup-center
  clear-all
  ask patches [
  if pxcor = (- (edge / 2)) and pycor >= (- (edge / 2)) and pycor <= (0 + (edge / 2))
  [set pcolor red]
  if pycor = (- (edge / 2)) and pxcor >= (- (edge / 2)) and pxcor <= (0 + (edge / 2))
  [set pcolor red]
  if pxcor = (edge / 2) and pycor >= (- (edge / 2)) and pycor <= (0 + (edge / 2))
  [set pcolor red]
  if pycor = (edge / 2) and pxcor >= (- (edge / 2)) and pxcor <= (0 + (edge / 2))
  [set pcolor red]
  ]
end

你能告诉我哪里出错了吗？感谢您的回复

Answer 1

问题是edge 没有在 NelLogo 中定义。相反，世界的边缘由min-pxcor、max-pxcor、min-pycor 和max-pycor 描述。因此，您的程序（稍微简化）将是

to setup-center
  clear-all
  let top max-pycor / 2
  let bottom min-pycor / 2
  let left-side min-pxcor / 2
  let right-side max-pxcor / 2
  ask patches [
    if pxcor = left-side and pycor >= bottom and pycor <= (0 + top)
    [set pcolor red]
    if pycor = bottom and pxcor >= left-side and pxcor <= (0 + right-side)
    [set pcolor red]
    if pxcor = right-side and pycor >= bottom and pycor <= (0 + top)
    [set pcolor red]
    if pycor = top and pxcor >= left-side and pxcor <= (0 + right-side)
    [set pcolor red]
  ]
end

这种方法查询世界上的每个补丁，如果世界很大，效率相对较低。但是，对于相当小的世界，它运行良好，并且在设置中您只需要执行一次。

希望这会有所帮助， 查尔斯