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Subject: Re: [Boost-users] [BGL] brandes betweenness vs networkx
From: Andrew Sutton (andrew.n.sutton_at_[hidden])
Date: 2008-11-12 09:52:30

> I would guess that the difference has to do with networkx's normalization
>> of between values, but I couldn't say for certain. It might also be that
>> networkx is following undirected edges twice, resulting in twice the value.
>> That would definitely be worth looking into.
> I turned off networkx's normalization - so that is not it. The boost code
> explicitly divides by 2 for undirected at the end.
> I'll try calculating one by hand and see which code comes up with what I
> think is Brandes metric.

I did not catch that... I have absolutely no idea what the rationale for
this is. I might guess that the author's intent was to normalize (kind of)
w.r.t. degree. You know, degree of a vertex in an undirected graph is twice
that of the same directed graph... That probably isn't the right thing to do
in this case.

If you're by-hand computation matches network-x, then file a ticket on it
and I'll patch it up tomorrow or Friday.

Andrew Sutton

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