
Boost Users : 
Subject: Re: [Boostusers] Implementing matrix_as_graph to convert a boost::numeric::ublas::matrix to a "graph"
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 20090328 23:43:25
AMDG
John Burgoon wrote:
> I wrote a small program in C++ using boost to read a neural network file
> (directional graph of a feedforward multilayer perceptron) into
> boost::numeric::ublas::matrix. The typical file size creates matrices of
> various sizes, anywhere from a 36x36 to a 130x130 matrix (of floats  edge
> weights between 0 and 1 to four sig figs). About half to twothirds of the
> values are 0 in a typical graph, so I think of them as sparse. There are
> thousands of such files, so I have been really thrilled with the speed of
> boost. (I was doing this work with Perl last year. Ahem.)
>
> Now I want to implement the boost matrix_as_graph library so that I can
> convert my matrix into a graph and then implement various network metrics on
> the graph (such as betweenness_centrality.hpp). However, when I looked in
> the docs at
> http://www.boost.org/doc/libs/1_38_0/boost/graph/matrix_as_graph.hpp
> I was dismayed to find only a code listing: no explanation, no examples.
>
> I'm not the strongest C++ coder. Can someone point me to an example or
> tutorial of how to implement matrix_as_graph to turn a ublas::matrix into a
> graph? I think I could puzzle it out if I could find an example to emulate.
>
> I'll repay the community with a simple blog tutorial of how I did it, if
> someone can only help me get started.
>
I don't know what matrix_as_graph is designed for, but it can't
handle uBlas matrices.
In Christ,
Steven Watanabe
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