运行 Dijkstra 算法后如何获取“for”循环结果并将其保存为列表？

Question

我正在尝试解决 Dijkstra 算法的问题。基本上，我想随机选择开始和结束节点，并在配对节点并运行算法后找到每条路径的距离。最后，我想将结果保存为列表。到目前为止，代码运行良好，但是，我在将结果保存为列表时遇到了挑战。 这是我使用的代码。

import random
from random import seed
from random import random
from random import randint
import pandas as pd
import numpy as np
import statistics 

distance = [(0,7,3,0,0),(7,0,1,2,6),(3,1,0,2,0),(0,2,2,0,4),(0,6,0,4,0)]
dist = np.array(distance)
graph = dist

# Python program for Dijkstra's  

from collections import defaultdict 
class Graph:   
    def minDistance(self,dist,queue): 
        minimum = float("Inf") 
        min_index = -1
        for i in range(len(dist)): 
            if dist[i] < minimum and i in queue: 
                minimum = dist[i] 
                min_index = i 
        return min_index  
    def printPath(self, parent, end): 
        if parent[end] == -1 :  
            #print (end), 
            return
        self.printPath(parent , parent[end]) 
        #print (end),     
    def printSolution(self, dist, parent): 
        #print("Vertex and Path \t\tDistance from Source") 
        #print((start, end, dist[end])), self.printPath(parent,end)  #if you want to see start and end nodes

        print(dist[end]), self.printPath(parent,end)  #if you do not want to see start and end nodes

    '''Function that implements Dijkstra's single source shortest path 
    algorithm for a graph represented using adjacency matrix 
    representation'''
    def dijkstra(self, graph, start): 
        row = len(graph) 
        col = len(graph[0]) 
        dist = [float("Inf")] * row 
        parent = [-1] * row 
        dist[start] = 0
        queue = [] 
        for i in range(row): 
            queue.append(i) 
        while queue: 
            u = self.minDistance(dist,queue)  
            queue.remove(u) 
            for i in range(col): 
                '''Update dist[i] only if it is in queue, there is 
                an edge from u to i, and total weight of path from 
                start to i through u is smaller than current value of 
                dist[i]'''
                if graph[u][i] and i in queue: 
                    if dist[u] + graph[u][i] < dist[i]: 
                        dist[i] = dist[u] + graph[u][i] 
                        parent[i] = u   
        self.printSolution(dist,parent)   
g= Graph() 

seed(1)
start1 = []
for x in range(3):
    start = randint(0, 3)
    start1.append(start)

seed(3)
end1 = []
for x in range(3):
    end = randint(2,4)
    end1.append(end)

start = start1
end = end1

results = []
for i in start1:
    for q in end1:
        start = i
        end = q
        if i != q:
            results.append(g.dijkstra(graph,i))

上面的代码产生了这个结果...

1
6
6
3
9
9
6
6

当我调用保存的列表时，我得到“无”值。

results

[None, None, None, None, None, None, None, None]

我希望得到如下结果：

[1,6,6,3,9,9,6,6,]

由于我是使用 python 的初学者，如果有人可以帮助我将结果保存为列表，我将非常感激。

Answer 1

在results 中附加来自g.dijkstra(graph,i) 的返回值。而 b/c 没有返回命令，它返回None。因此，您仅附加 None。 在dijkstra() 的末尾添加return some-value，它应该可以工作。