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Re: [igraph] Python: Converting large, sparse network from Scipy to Igra


From: Tamás Nepusz
Subject: Re: [igraph] Python: Converting large, sparse network from Scipy to Igraph
Date: Wed, 3 Jul 2013 17:51:04 +0200

> data.toarray() converts the sparse matrix to dense/full format, which blows 
> my memory out of the water. What ought I to be doing?
Use the nonzero() method of your sparse matrix to extract the row/column 
indices of the nonzero elements of your matrix, then construct the graph using 
the standard Graph() constructor which accepts an edge list. If you want to 
keep the weights as well, there should be a way in SciPy to extract the values 
of the nonzero elements in the same order (probably A[A.nonzero()] will do the 
trick) and then you can assign that vector to the "weight" attribute of your 
graph.

-- 
T.


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