在Python中实现A star算法的问题

问题描述

该程序利用A *算法查找从起始城市（海得拉巴）到终点城市（伊斯兰堡）的最短路径

此python程序可以运行，但是它错误地复制了数据，例如 可能探索过的城市：['海得拉巴'，'卡拉奇'，'奎塔'，'奎塔'，'苏库尔'，'苏丹'，'拉合尔'，' Bahawalpur”，“ Bahawalpur ”，“ Peshawar”，“伊斯兰堡”] 可能的城市数量：11

第二季度。我想做的另一件事是跟踪A star算法采取的步骤并将其显示为输出。

输入

所以在hyderabad.txt文件中，我添加了两个城市之间的路径距离 例如

Hyderabad,Quetta,160`
Hyderabad,Karachi,60
Hyderabad,Sukkur,60
Karachi,80
Quetta,Peshawar,120
Peshawar,Islamabad,40
Sukkur,Multan,80
Sukkur,Bahawalpur,160
Multan,60
Multan,Lahore,80
Bahawalpur,160
Lahore,100

在hyderabad_sld.txt文件中，我添加了试探法

Hyderabad,200
Islamabad,0
Quetta,100
Karachi,140
Sukkur,220
Multan,140
Bahawalpur,80
Lahore,20
Peshawar,50

import heapq
class priorityQueue:
    def __init__(self):
        self.cities = []

    def push(self,city,cost):
        heapq.heappush(self.cities,(cost,city))

    def pop(self):
        return heapq.heappop(self.cities)[1]

    def isEmpty(self):
        if (self.cities == []):
            return True
        else:
            return False

    def check(self):
        print(self.cities)

class ctNode:
    def __init__(self,distance):
        self.city = str(city)
        self.distance = str(distance)

hyderabad = {}


def makedict():
    file = open("Hyderabad.txt",'r')
    for string in file:
        line = string.split(',')
        ct1 = line[0]
        ct2 = line[1]
        dist = int(line[2])
        hyderabad.setdefault(ct1,[]).append(ctNode(ct2,dist))
        hyderabad.setdefault(ct2,[]).append(ctNode(ct1,dist))

def makeheuristicdict():
    h = {}
    with open("hyderabad_sld.txt",'r') as file:
        for line in file:
            line = line.strip().split(",")
            node = line[0].strip()
            sld = int(line[1].strip())
            h[node] = sld
    return h

def heuristic(node,values):
    return values[node]

def astar(start,end):
    path = {}
    distance = {}
    q = priorityQueue()
    h = makeheuristicdict()

    q.push(start,0)
    distance[start] = 0
    path[start] = None
    expandedList = []

    while (q.isEmpty() == False):
        current = q.pop()
        expandedList.append(current)

        if (current == end):
            break

        for new in hyderabad[current]:
            g_cost = distance[current] + int(new.distance)

        # print(new.city,new.distance,"Now : " + str(distance[current]),g_cost)

            if (new.city not in distance or g_cost < distance[new.city]):
            distance[new.city] = g_cost

            f_cost = g_cost + heuristic(new.city,h)
            q.push(new.city,f_cost)
            path[new.city] = current

    printoutput(start,end,path,distance,expandedList)

def printoutput(start,expandedlist):
   finalpath = []
   i = end

   while (path.get(i) != None):
       finalpath.append(i)
       i = path[i]
   finalpath.append(start)
   finalpath.reverse()
   print("A star search problem >> Islamabad")
   print("\tHyderabad => Islamabad")
   print("=======================================================")
   print("Cities that maybe explored \t\t: " + str(expandedlist))
   print("number of possible cities \t\t: " + str(len(expandedlist)))
   print("=======================================================")
   print("City with shortest distance \t: " + str(finalpath))
   print("Number of cities passed \t\t\t: " + str(len(finalpath)))
   print("Total distance \t\t\t\t\t\t: " + str(distance[end]))

def main():
   src = "Hyderabad"
   dst = "Islamabad"
   makedict()
   astar(src,dst)

if __name__ == "__main__":
    main()

解决方法

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