当没有更多的补丁可以占用时打印 "no patch"

Question

我想在没有更多补丁可占用时打印 "no path"，而不是收到错误 "MOVE-TO expected input to be an agent but got NOBODY instead." 警告。我做了几件事，但没有奏效。最后，我做了以下事情；

 ask migrants
  [let pot-target patches with [value < 11 and not any? turtles-here]
   let target pot-target with [count neighbors with [any? turtles-here with [value < 11]] >= 1]
    if target = 0 [print (word "no patch")]
    if (target != 0 and (status != "resident")) [move-to min-one-of target [value]
                                              set status "resident"
                                              set color blue]


  ]

这里是完整的代码

breed [migrants migrant]
breed [residents resident]

patches-own [value]
turtles-own [income
status]

to setup
  ca
  let total problo + probmid + probhi
  if (total != 100) 
     [print (word "prob is more than 100")]
  ask patches [set value random-normal 10 3
  let patch-value value
    set pcolor scale-color (gray - 5) patch-value 10 3]
  ask patches
  [if random 100 < 3
    [sprout-residents 1
      [set color red
       set shape "default"
       set size 1
       set status "resident"   
      ]
    ]
  ]
end

to go

  ask patches 
  [if random 100 < 1 
    [sprout-migrants 1
      [set color green
       set shape "default"
       set size 1 
        set status "migrant"
       set-move 
  ]]]

end

to set-move
 ask migrants
  [let pot-target patches with [value < 11 and not any? turtles-here]
   let target pot-target with [count neighbors with [any? turtles-here with [value < 11]] >= 1]
    if target = 0 [print (word "no patch")]
    if (target != 0 and (status != "resident")) [move-to min-one-of target [value]
                                              set status "resident"
                                              set color blue]


  ] 

end

Answer 1

您混淆了一个代理集和该代理集中的 count 个代理。这一行：

let target pot-target with [count neighbors with [any? turtles-here with [value < 11]] >= 1]

returns 一个代理集。所以你的变量"target"就是所有符合你条件的补丁。如果没有满足你条件的patch，那么agentset不是0，而是agentset的count是

因此您需要将 if target = 0 [print (word "no patch")] 替换为 if count target = 0 [print (word "no patch")] 或 if not any? [print (word "no patch")]。

当没有更多的补丁可以占用时打印 "no patch"

Print "no patch" when there is no more patches to occupy

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