为什么 LightGraphs.betweenness_centrality() 运行这么久

问题描述

当我尝试使用 julia 的 LightGraphs 包计算 SimpleWeightedGraph 的 betweenness_centrality() 时，它会无限期地运行。它不断增加它的 RAM 使用量，直到在某个时候它崩溃而没有错误消息。我的图表有问题吗？或者找出此问题原因的最佳方法是什么？

我的图形不是由 LightGraphs 生成的，而是由另一个库 Flashweave 生成的。我不知道这是否重要...

未加权的 simplegraph 或我在 LightGraphs 中创建的加权图不会出现此问题...

using BenchmarkTools
using Flashweave
using ParserCombinator
using GraphIO.GML
using LightGraphs
using SimpleWeightedGraphs

data_path = /path/to/my/data

netw_results = Flashweave.learn_network(data_path,sensitive     = true,heterogeneous = false)

dummy_weighted_graph = SimpleWeightedGraph(smallgraph(:house))
# {5,6} undirected simple Int64 graph with Float64 weights


my_weighted_graph = graph(netw_results_no_Meta)
# {6558,8484} undirected simple Int64 graph with Float64 weights

# load_graph() only loads unweighted graphs
save_network(gml_no_Meta_path,netw_results_no_Meta)
my_unweighted_graph = loadgraph(gml_no_Meta_path,GMLFormat())
# {6558,8484} undirected simple Int64 graph



@time betweenness_centrality(my_unweighted_graph)
# 12.467820 seconds (45.30 M allocations: 7.531 GiB,2.73% gc time)

@time  betweenness_centrality(dummy_weighted_graph)
# 0.271050 seconds (282.41 k allocations: 13.838 MiB)

@time  betweenness_centrality(my_weighted_graph)
# steadily increasing RAM usage until RAM is full and julia crashes.

解决方法

您是否检查过您的图表是否包含负权重？ LightGraphs.betweenness_centrality() 使用 Dijkstra 的最短路径来计算中介中心性，因此期望非负权重。

LightGraphs.betweenness_centrality() 不检查非法/无意义的图表。这就是它没有抛出错误的原因。该问题已报告 here，但现在，如果您不确定它们是否合法，请检查您自己的图表。

A = Float64[
    0  4  2
    4  0  1
    2  1  0
]

B = Float64[
    0  4  2
    4  0  -1
    2  -1  0
]

graph_a = SimpleWeightedGraph(A)
# {3,3} undirected simple Int64 graph with Float64 weights
graph_b = SimpleWeightedGraph(B)
# {3,3} undirected simple Int64 graph with Float64 weights

minimum(graph_a.weights)
# 0.00
minimum(graph_b.weights)
# -1.00

@time betweenness_centrality(graph_a)
# 0.321796 seconds (726.13 k allocations: 36.906 MiB,3.53% gc time)
# Vector{Float64} with 3 elements
# 0.00
# 0.00
# 1.00

@time betweenness_centrality(graph_b)
# reproduces your problem.

此问题在此处发布之前已在 https://github.com/JuliaGraphs/LightGraphs.jl/issues/1531 中得到解答。正如决议中提到的，图中的权重为负。 Dijkstra 不处理负权重的图，LightGraphs 介数中心性使用 Dijkstra。

julia lightgraphs