TypeError：+：'dict'和'float'

Question

此代码的第26行给出了错误，但我无法修复它。请帮我搞清楚。 这是一行： path[road]['distance_from_start'] = path.get(road, {}).get('distance_from_start') + path.get(road, {}).get('distance_to_neighbor') 它应该找到的是地图中起点和目标目标之间的最短路径，其间有多个中间站点。

import math
def my_function(M, start, goal):
    frontier = set([start])
    expanded = set()
    chosen = start
    chosen_coordinates = M.intersections[chosen]
    goal_coordinates = M.intersections[goal]
    roads_to_choose = M.roads[chosen]
    path = {}
    while frontier != set():
        if chosen != goal:
            for road in roads_to_choose:
                if road not in expanded:
                    frontier.add(road)
                    path[road] = {}
                    path[road]['coordinate'] = {}
                    path[road]['roads'] = {}
                    path[road]['distance_to_goal'] = {}
                    path[road]['distance_to_neighbor'] = {}
                    path[road]['distance_from_start'] = {}
                    path[road]['g_plus_h'] = {}
                    path[road]['path_list'] = {}
                    path[road]['coordinate'] = M.intersections[road]
                    path[road]['roads'] = M.roads[road]
                    path[road]['distance_to_neighbor'] = math.sqrt(((M.intersections[road][0]-chosen_coordinates[0])**2) + ((M.intersections[road][1]-chosen_coordinates[1])**2))
                    path[road]['distance_from_start'] = path.get(road, {}).get('distance_from_start') + path.get(road, {}).get('distance_to_neighbor')
                    path[road]['distance_to_goal'] = math.sqrt(((goal_coordinates[0]-M.intersections[road][0])**2) + ((goal_coordinates[1]-M.intersections[road][1])**2))
                    path[road]['g_plus_h'] = path[road]['distance_from_start'] + path[road]['distance_to_goal']
                    path[road]['path_list'] = path[chosen]['path_list'].append(road)
            frontier.remove(chosen)
            expanded.add(chosen)
            if x not in expanded:
                chosen = min(path.keys(), key=lambda x:path[x]['g_plus_h'])
                path[road]['distance_from_start'] = path.get(chosen, {}).get('distance_from_start')
        else:
            print("Short path called")  
            return path[goal]['path_list']

Answer 1

您正在尝试添加两个字典项：

x={}
y={}
z = x+ y

这是错误的方法，这就是为什么你会收到这个错误。究竟你想用这两个dictonary做什么，你的结果取决于那个。如果你想合并它们，那么试试这个：

在Python 3.5或更高版本中，：

z = {**x, **y}

在Python 2中，（或3.4或更低版本）编写一个函数：

def merge(x, y):
    z = x.copy()   
    z.update(y)   
    return z
z = merge(x, y)

通过查看代码，可以通过更改开头的分配来解决问题，更改

path[road]['distance_to_neighbor'] = 0
path[road]['distance_from_start'] = 0

然后你就能得到你的结果。