networkx 无法计算代数连通度。

Question

我可以使用以下方法在几分之一秒内计算出20个顶点的完全图的代数连通度：

import networkx
D = {}
for i in range(20):
    D[i] = [j for j in range(20)]
G = networkx.Graph(D)
networkx.algebraic_connectivity(G)

然而，在我生成一个图表（有20个节点）的过程中，我要求networkx计算其代数连通度，但它一直运行而没有出现错误。这是这个图表：

import networkx

D = {0: [32, 33, 19, 5, 21, 37, 6, 38, 39, 41, 26, 42, 11, 43, 28, 44, 15, 31], 5: [32, 0, 33, 19, 37, 21, 6, 22, 38, 39, 41, 26, 42, 11, 43, 44, 28, 15, 31], 6: [0, 32, 33, 19, 5, 37, 21, 22, 38, 39, 41, 26, 42, 11, 43, 28, 44, 15, 31], 11: [32, 0, 33, 19, 21, 37, 5, 6, 22, 38, 39, 41, 26, 42, 43, 28, 44, 15, 31], 15: [0, 32, 33, 19, 5, 21, 37, 6, 22, 38, 39, 41, 26, 42, 11, 43, 28, 44, 31], 19: [0, 32, 33, 5, 21, 37, 6, 22, 38, 39, 41, 26, 42, 11, 43, 28, 44, 15, 31], 21: [32, 0, 33, 19, 37, 5, 6, 22, 38, 39, 41, 26, 42, 11, 43, 28, 44, 15, 31], 22: [32, 33, 19, 5, 21, 37, 6, 38, 39, 41, 26, 42, 11, 43, 28, 44, 15, 31], 26: [0, 32, 33, 19, 5, 21, 37, 6, 22, 38, 39, 41, 42, 11, 43, 28, 44, 15, 31], 28: [32, 0, 33, 19, 21, 37, 5, 6, 22, 38, 39, 41, 26, 42, 11, 43, 44, 15, 31], 31: [32, 0, 33, 19, 5, 21, 37, 6, 22, 38, 39, 41, 26, 42, 11, 43, 28, 44, 15], 32: [0, 33, 19, 5, 21, 37, 6, 22, 38, 39, 41, 26, 42, 11, 43, 28, 44, 31, 15], 33: [0, 32, 19, 5, 21, 37, 6, 22, 38, 39, 41, 26, 42, 11, 43, 28, 44, 15, 31], 37: [32, 0, 33, 19, 5, 21, 6, 22, 38, 39, 41, 26, 42, 11, 43, 28, 44, 31, 15], 38: [32, 0, 33, 19, 21, 37, 5, 6, 22, 39, 41, 26, 42, 11, 43, 28, 44, 15, 31], 39: [0, 32, 33, 19, 5, 21, 37, 6, 22, 38, 41, 26, 42, 11, 43, 28, 44, 15, 31], 41: [32, 0, 33, 19, 21, 37, 5, 38, 6, 22, 39, 26, 42, 11, 43, 28, 44, 15, 31],  42: [32, 0, 33, 19, 21, 37, 5, 6, 22, 38, 39, 41, 26, 11, 43, 28, 44, 15, 31], 43: [32, 0, 33, 19, 21, 37, 5, 6, 22, 38, 39, 41, 26, 42, 11, 28, 44, 15, 31], 44: [32, 0, 33, 19, 5, 21, 37, 38, 6, 22, 39, 41, 42, 26, 11, 43, 28, 15, 31]}

G = networkx.Graph(D)
networkx.algebraic_connectivity(G)

有什么原因导致这种情况，如何修复？

- Keivan

Answer 1

似乎在networkx.algebraic_connectivity()默认使用的tracemin方法中存在一个bug。尝试使用：

networkx.algebraic_connectivity(G, method='lanczos')

- Aric

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这是一个非常简单的修复。非常感谢您指出它。 - Keivan

补充Aric的评论，这是networkx中已知的一个bug。 - Arya McCarthy