NetLogo A-Star path finding

最新推荐文章于 2022-03-12 13:33:22 发布

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最新推荐文章于 2022-03-12 13:33:22 发布

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/henyihanwobushi/archive/2013/04/15/3021520.html

本文介绍了一种使用NetLogo GUI实现A*路径寻找算法的方法。通过在界面上设置起点和终点，并定义了障碍物，该算法能够找到从起点到终点的最短路径。代码中详细描述了如何初始化地图、设置节点状态以及更新路径。

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you should add a "setup" button and an "go" button on the GUI of the netlogo, like this:

and then you paste the code here to the code tab:

patches-own
[
  can-reach?
  parent-node
  is-open?
  is-close?
  
  g-score
  f-score
  
  temp-g-score
]

globals
[
  move-space
  open-set
  close-set
  start-node
  goal-node
  
  a-stop
  b-stop
]

to setup
  clear-all
  set a-stop 1
  set b-stop 0
  ask patches
  [
    set can-reach? true
    set is-open? false
    set is-close? false
    set parent-node -1
  ]
  ask patches
  [
    if pxcor + pycor < 40 and pxcor + pycor > -50
    [
      if pxcor = pycor
      [
        set can-reach? false
      ]
      if pxcor = pycor + 1
      [
        set can-reach? false
      ]
      if pxcor = pycor - 1
      [
        set can-reach? false
      ]
    ]
    if pxcor - pycor < 40 and pxcor - pycor > -40
    [
      if pxcor + pycor = 40
      [
        set can-reach? false
      ]
      if pxcor + pycor = 41
      [
        set can-reach? false
      ]
      if pxcor + pycor = 39
      [
        set can-reach? false
      ]
    ]
  ]
  ask patches
  [
    if-else can-reach?
    [
      set pcolor 87
    ]
    [
      set pcolor 17
    ]
  ]
  set start-node patch -40 40
  ask start-node
  [
    set is-open? true
  ]
  set goal-node patch 40 -40
  reset-ticks
end

to go
  ask patches with [is-open? = true]
  [
    set g-score 0
    set f-score g-score + sqrt(([pxcor] of self - [pxcor] of goal-node)*([pxcor] of self - [pxcor] of goal-node) + ([pycor] of self - [pycor] of goal-node)*([pycor] of self - [pycor] of goal-node))
  ]
  while [(count patches with [is-open? = true]) != 0]
  [
    set open-set patches with [is-open? = true]
    let min-f-score min [f-score] of open-set
    let current-node one-of open-set with [f-score = min-f-score]
    if current-node = goal-node
    [
      color-the-path
      stop
    ]
    ask current-node
    [
      set is-open? false
      set is-close? true
      ask neighbors
      [
        set temp-g-score [g-score] of current-node + 1.42
      ]
      ask neighbors4
      [
        set temp-g-score temp-g-score - 0.42
      ]
      ask neighbors
      [
        if can-reach?
        [
          set pcolor pcolor + -0.3
          if-else is-close?
          [
            if-else temp-g-score >= g-score
            [
            ]
            [
              if is-open? = false or temp-g-score < g-score
              [
                set parent-node current-node
;                show word self current-node
                set g-score temp-g-score
                set f-score g-score + sqrt(([pxcor] of self - [pxcor] of goal-node)*([pxcor] of self - [pxcor] of goal-node) + ([pycor] of self - [pycor] of goal-node)*([pycor] of self - [pycor] of goal-node))
                if is-open? = false
                [
                  set is-open? true
                ]
              ]
            ]
          ]
          [
            if is-open? = false or temp-g-score < g-score
            [
              set parent-node current-node
;              show word self current-node
              set g-score temp-g-score
              set f-score g-score + sqrt(([pxcor] of self - [pxcor] of goal-node)*([pxcor] of self - [pxcor] of goal-node) + ([pycor] of self - [pycor] of goal-node)*([pycor] of self - [pycor] of goal-node))
              if is-open? = false
              [
                set is-open? true
              ]
            ]
          ]
        ]
      ]
    ]
    tick
  ]
end

to get-f-score
  let h-score sqrt(([pxcor] of self - [pxcor] of goal-node)*([pxcor] of self - [pxcor] of goal-node) + ([pycor] of self - [pycor] of goal-node)*([pycor] of self - [pycor] of goal-node))
  set f-score g-score + h-score
end

to color-the-path
  let p goal-node
  while [p != -1]
  [
    ask p
    [
      set pcolor black
      set p parent-node
    ]
  ]
  show word "finded the shortest path: " [f-score] of goal-node
  tick
end

then you click on the "start" button and click on the "go" button, you will see a A-star path finding algorithm.

Sorry for that there is not much comments there, and I did have no ability for increase the speed of the algorithm, then the code is ineffiency and ugly. hope for that it's useful to some body(even this is beyond the dream of myself...).

转载于:https://www.cnblogs.com/henyihanwobushi/archive/2013/04/15/3021520.html