如何使用python将邻接矩阵转换为邻接列表? [英] How to convert an adjacency matrix to an adjacency list with python?

问题描述

我有一个类似的邻接矩阵:

I have an adjacency matrix like:

[[  0.,  15.,   0.,   7.,  10.,   0.],
    [ 15.,   0.,   9.,  11.,   0.,   9.],
    [  0.,   9.,   0.,   0.,  12.,   7.],
    [  7.,  11.,   0.,   0.,   8.,  14.],
    [ 10.,   0.,  12.,   8.,   0.,   8.],
    [  0.,   9.,   7.,  14.,   8.,   0.]]

如何将其转换为此处的邻接列表?

How can I convert it to an adjacency list like this one down here?

graph = {'1': [{'2':'15'}, {'4':'7'}, {'5':'10'}],
'2': [{'3':'9'}, {'4':'11'}, {'6':'9'}],
'3': [{'5':'12'}, {'6':'7'}],
'4': [{'5':'8'}, {'6':'14'}],
'5': [{'6':'8'}]}

?

推荐答案

保留一组edges中已添加的边的列表.这些边存储在frozenset中，因此不会复制已添加的对.

Keep a list of already added edges in a set edges. Those edges are stored in a frozenset, so already added pairs are not replicated.

然后通过枚举以起始索引为1的外部列表，然后以起始索引为1的内部列表来构建图形.在值上使用if条件可以消除零值条目:

Then build your graph by enumerating the outer list with a starting index of one, then the inner list also with a starting index of one. Zero valued entries are eliminated with the if condition on values:

from collections import defaultdict
from pprint import pprint

l =[[  0.,  15.,   0.,   7.,  10.,   0.],
    [ 15.,   0.,   9.,  11.,   0.,   9.],
    [  0.,   9.,   0.,   0.,  12.,   7.],
    [  7.,  11.,   0.,   0.,   8.,  14.],
    [ 10.,   0.,  12.,   8.,   0.,   8.],
    [  0.,   9.,   7.,  14.,   8.,   0.]]    

graph = defaultdict(list)
edges = set()

for i, v in enumerate(l, 1):
    for j, u in enumerate(v, 1):
        if u != 0 and frozenset([i, j]) not in edges:
            edges.add(frozenset([i, j]))
            graph[i].append({j: u})

pprint(graph)
# {1: [{2: 15.0}, {4: 7.0}, {5: 10.0}],
#  2: [{3: 9.0}, {4: 11.0}, {6: 9.0}],
#  3: [{5: 12.0}, {6: 7.0}],
#  4: [{5: 8.0}, {6: 14.0}],
#  5: [{6: 8.0}]}

使用将list作为默认值的defaultdict可以帮助动态构建列表值的字典.

Using a defaultdict which takes a list as default value will help build the list-valued dictionary on the fly.

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