这是我第一次尝试实施Dijkstra算法，所以也许我误解了它是如何完成的。也就是说，当所有节点具有相同的值1时，我能够使算法工作，但是如果我将节点更改为更高的值，例如接近开始的2（例如x = 5，y = 0）似乎陷入困境，认为没有解决方案。如果我把更高的价值放在更远的地方，它似乎就可以了。我已多次看过它，看看我是否错过了什么，但我不知所措。对我可能出错的任何帮助表示赞赏！
import sys
import copy
class Node:
def __init__(self, x, y, cost, goal, start):
self.x = x #pos X
self.y = y #pos Y
self.goal = goal #goal?
self.start = start #start?
self.cost = cost #cost of tile
self.nodeID = "{}{}".format(str(x), str(y)) #unique node identifier
class NodeRecord:
def __init__(self, x, y, cost, goal, start, connection, costSoFar):
self.node = Node(x, y, cost, goal, start) #create new node for record
self.connection = connection
self.costSoFar = costSoFar
def pathfind(graph, startX, startY, arr):
startRecord = NodeRecord(startX, startY, 0, False, True, None, 0)
openList = []
closedList = []
openList.append(startRecord)
while len(openList) > 0:
current = smallestElement(openList)
if current.node.goal == True:
break
connections = getConnections(current, arr) #gets adjacent nodes and stores in connections list
#search connections for new nodes
for connection in connections:
endNodeCost = current.costSoFar + connection.node.cost
if containsNode(connection.node.nodeID, closedList): #closed node, skip
continue
elif containsNode(connection.node.nodeID, openList): #worse route, skip
if connection.node.cost <= endNodeCost:
continue
#new node record found add it to list
else:
connection.node.goal = goalNode(connection.node.x, connection.node.y, arr)
if containsNode(connection.node.nodeID, openList) == False:
openList.append(connection)
#remove the connection from the open list and add it to the closed list
tmpNode = openList[0]
del openList[0]
closedList.append(tmpNode)
path = []
if current.node.goal == False: #there is no possible solution
print("No solution\n")
else: #compile list of connections
while current.node.start == False:
path.append(current)
current = current.connection
#for i in closedList:
# print("x: {} y: {} cost: {}".format(i.node.x, i.node.y, i.node.cost))
return reversed(path)
def containsNode(nodeID, nodeList):
for record in nodeList:
if record.node.nodeID == nodeID:
return True
return False
def getConnections(current, arr):
connections = []
lastCost = current.costSoFar
x = current.node.x
y = current.node.y
#add any valid connecting nodes from current node
if outOfBounds(x + 1, y, arr) == False and arr[y][x + 1] != '#':
currCost = getCost(x + 1, y, arr)
node = NodeRecord(x + 1, y, currCost, goalNode(x + 1, y, arr), False, current, lastCost + currCost)
connections.append(node)
if outOfBounds(x - 1, y, arr) == False and arr[y][x - 1] != '#':
currCost = getCost(x - 1, y, arr)
node = NodeRecord(x - 1, y, currCost, goalNode(x - 1, y, arr), False, current, lastCost + currCost)
connections.append(node)
if outOfBounds(x, y + 1, arr) == False and arr[y + 1][x] != '#':
currCost = getCost(x, y + 1, arr)
node = NodeRecord(x, y + 1, currCost, goalNode(x, y + 1, arr), False, current, lastCost + currCost)
connections.append(node)
if outOfBounds(x, y - 1, arr) == False and arr[y - 1][x] != '#':
currCost = getCost(x, y - 1, arr)
node = NodeRecord(x, y - 1, currCost, goalNode(x, y - 1, arr), False, current, lastCost + currCost)
connections.append(node)
return connections
def getCost(x, y, arr):
if isNum(arr[y][x]):
return int(arr[y][x])
#no cost for goal
elif arr[y][x] == 'G':
return 0
#error
return -1
def isNum(n):
try:
int(n)
return True
except ValueError:
return False
def goalNode(x, y, arr):
if arr[y][x] == 'G':
return True
return False
def outOfBounds(x, y, arr):
if x >= len(arr[0]):
return True
elif x < 0:
return True
if y >= len(arr):
return True
elif y < 0:
return True
return False
def smallestElement(openList):
tmpNode = NodeRecord(None, None, None, None, None, None, None)
smallest = 99
for i in openList:
if i.node.cost < smallest:
smallest = i.node.cost
tmpNode = i
return tmpNode
def getStart(arr):
startX = 0
startY = 0
for j in range(0, 4):
for i in range(0, 5):
if arr[j][i] == 'S':
startX = i
startY = j
coords = (startX, startY)
return coords
def main():
arr = [[]]
tmp = ['S', '1', '1', '1', '1', '1', '1', '1', '1', '1']
arr[0] = tmp
tmp = ['1', '#', '#', '#', '#', '1', '1', '#', '1', '1']
arr.append(tmp)
tmp = ['1', '#', '1', '1', '1', '#', '1', '#', '1', '1']
arr.append(tmp)
tmp = ['1', '#', '1', '#', '1', '#', '1', '#', '1', '1']
arr.append(tmp)
tmp = ['1', '#', '1', '#', '1', '1', '1', '1', '1', '1']
arr.append(tmp)
tmp = ['1', '#', '1', '#', '#', '#', '#', '#', '#', '#']
arr.append(tmp)
tmp = ['1', '#', '1', '1', '1', '1', '1', '1', '1', 'G']
arr.append(tmp)
startCoord = getStart(arr)
path = pathfind(arr, startCoord[0], startCoord[1], arr)
for i in path:
arr[i.node.y][i.node.x] = '@'
for j in range(0, 7):
for i in range(0, 10):
sys.stdout.write(arr[j][i])
sys.stdout.write("\n")
if __name__ == "__main__":
main()
答案 0 :(得分：0)
我发现了这个问题，并希望将它发布给任何可能在将来犯同样错误的人。 问题出在这里。
tmpNode = openList[0]
del openList[0]
closedList.append(tmpNode)
第一个节点被删除并添加到关闭列表而不是当前节点。这是我纠正它的方式。
removeNode(current, openList)
closedList.append(current)
...
def removeNode(node, openList):
pos = 0
for i in openList:
if i.node.x == node.node.x and i.node.y == node.node.y:
del openList[pos]
pos += 1