Question

我发现这个算法在2D数组中找到路径（source）：

# Author: Christian Careaga (christian.careaga7@gmail.com)
# A* Pathfinding in Python (2.7)
# Please give credit if used

import numpy
from heapq import *


def heuristic(a, b):
    return (b[0] - a[0]) ** 2 + (b[1] - a[1]) ** 2

def astar(array, start, goal):

    neighbors = [(0,1),(0,-1),(1,0),(-1,0),(1,1),(1,-1),(-1,1),(-1,-1)]

    close_set = set()
    came_from = {}
    gscore = {start:0}
    fscore = {start:heuristic(start, goal)}
    oheap = []

    heappush(oheap, (fscore[start], start))

    while oheap:

        current = heappop(oheap)[1]

        if current == goal:
            data = []
            while current in came_from:
                data.append(current)
                current = came_from[current]
            return data

        close_set.add(current)
        for i, j in neighbors:
            neighbor = current[0] + i, current[1] + j            
            tentative_g_score = gscore[current] + heuristic(current, neighbor)
            if 0 <= neighbor[0] < array.shape[0]:
                if 0 <= neighbor[1] < array.shape[1]:                
                    if array[neighbor[0]][neighbor[1]] == 1:
                        continue
                else:
                    # array bound y walls
                    continue
            else:
                # array bound x walls
                continue

            if neighbor in close_set and tentative_g_score >= gscore.get(neighbor, 0):
                continue

            if  tentative_g_score < gscore.get(neighbor, 0) or neighbor not in [i[1]for i in oheap]:
                came_from[neighbor] = current
                gscore[neighbor] = tentative_g_score
                fscore[neighbor] = tentative_g_score + heuristic(neighbor, goal)
                heappush(oheap, (fscore[neighbor], neighbor))

    return False

'''Here is an example of using my algo with a numpy array,
   astar(array, start, destination)
   astar function returns a list of points (shortest path)'''

nmap = numpy.array([
    [0,0,0,0,0,0,0,0,0,0,0,0,0,0],
    [1,1,1,1,1,1,1,1,1,1,1,1,0,1],
    [0,0,0,0,0,0,0,0,0,0,0,0,0,0],
    [1,0,1,1,1,1,1,1,1,1,1,1,1,1],
    [0,0,0,0,0,0,0,0,0,0,0,0,0,0],
    [1,1,1,1,1,1,1,1,1,1,1,1,0,1],
    [0,0,0,0,0,0,0,0,0,0,0,0,0,0],
    [1,0,1,1,1,1,1,1,1,1,1,1,1,1],
    [0,0,0,0,0,0,0,0,0,0,0,0,0,0],
    [1,1,1,1,1,1,1,1,1,1,1,1,0,1],
    [0,0,0,0,0,0,0,0,0,0,0,0,0,0]])

print astar(nmap, (0,0), (10,13))

我完全迷失了它是如何工作的，但是它有效，所以没问题。但问题是该算法还使用从一行到另一行的45度移动，例如（0,0）至（1,1）而不是（0,0） - > （0,1） - ＆gt; （1,1）。这对我来说不是很好，所以有人可以告诉我如何编辑它以仅使用直接移动？

Answer 1

邻居列表定义了可能的移动：

neighbors = [(0,1),(0,-1),(1,0),(-1,0),(1,1),(1,-1),(-1,1),(-1,-1)]

如果您不想允许对角移动，请使用

neighbors = [(0,1),(0,-1),(1,0),(-1,0)]

如何编辑A *寻路算法以仅查找直线移动？

1 个答案: