获取访问图形权重的关键错误，networkx

如何解决获取访问图形权重的关键错误，networkx

我正在使用networkx创建一种算法来计算不同社区的模块化。现在我在做G [complst [i]] [complst [j]] ['weight']时遇到了这个关键问题，而我打印了complst [i]和compost [j]并发现这些值是正确的。有人可以帮忙吗？我尝试了许多方法对其进行调试，例如将它们保存在单独的变量中，但它们无济于事。

import networkx as nx
import copy
#load the graph made in previous task
G = nx.read_gexf("graph.gexf")
#set a global max modualrity value
maxmod = 0
#deep copy of the coriginal graph,since when removing edges,the graph will change
ori = copy.deepcopy(G)
#create an array for saving the edges to remove
arr = []
#see if all edges are broken,if not,keep looping,otherwise stop
while(G.number_of_edges()!=0):
    #find the edge_betweeness for each edge
    betweeness = nx.edge_betweenness_centrality(G,weight='weight',normalized=False)
    print('------------------******************--------------------')
    #sort the result in descending order and save all edges with the maximum betweenness to 'arr'
    sortbet = {k: v for k,v in sorted(betweeness.items(),key=lambda item: item[1],reverse=True)}
    #covert the dict to list for processing
    betlst = list(sortbet)
    for i in range(len(betlst)):
        if betlst[i] == betlst[0]:
            arr.append(betlst[i])
    #remove all edges with maximum betweeness from the graph
    G.remove_edges_from(arr)

    #find the leftover component,and convert the result to list for further modualrity processing
    lst = list(nx.connected_components(G))
    #!!!!!!!!testing and debugging the value,now the value is printed correctly
    print(G['pk_sullivan']['ChrisWarcraft']['weight'])

    #create a variable cnt to represent modularity in this graph
    cnt = 0
    #iterate the lst,which is each component(each component is saved as python set)
    for n in range(len(lst)):
        #convert each component from set to list for processing
        complst = list(lst[n])
        #if this component is a singleton,the modualrity for this component 0,so add 0 the current cnt
        if len(complst)==1:
            cnt += 0
        else:

            # calulate the modularity for this component by using combinations of edges
            for i in range(0,len(complst)):
                if i+1 <=len(complst)-1:
                    for j in range(i+1,len(complst)):
                        #!!!!!!!!! there is a bunch of my testing and find the value are printed all fine until "print(G[a][b]['weight'])""
                        print(i)
                        print(j)
                        print(complst)
                        a = complst[i]
                        print(type(a))
                        b = complst[j]
                        print(type(b))
                        print(G[a][b]['weight'])
                        #calculate the modualrity by using equation M = 1/2m*(weight(a,b)-degree(a)*degree(b)/2m)
                        cnt += 1/(2*ori.number_of_edges())*(G[a][b]['weight']-ori.degree(a)*ori.degree(b)/(2*ori.number_of_edges()))
                        #find the maximum modualrity and save this split of graph,end!
                        if cnt>=maxmod:
                            maxmod = cnt
                            newgraph = copy.deepcopy(G)
    print('maxmod is',maxmod)

这是错误，欢迎运行代码，希望我的代码插图对您有所帮助！

解决方法

您似乎正在尝试查找每个已连接组件内节点的所有组合的权重。但是问题是，您假设已连接组件中的所有节点都是一级连接，即通过单个边缘连接，这是错误的。

在您的代码中，您拥有：

...
for i in range(0,len(complst)):
    if i+1 <=len(complst)-1:
        for j in range(i+1,len(complst)):
...

然后尝试找到连接这两个节点的边缘的权重。 但是连接的组件中的每个边都没有连接到其余的。连接的组件仅意味着所有其他节点都可以可达。

因此，您应该遍历所连接的组件所生成的子图中的边缘或沿这些线的某些东西。