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[igraph] a few questions about saving and plotting a 50k nodes network


From: Yannick Rochat
Subject: [igraph] a few questions about saving and plotting a 50k nodes network
Date: Mon, 8 Feb 2010 14:31:18 +0100

Dear Gábor & al.,

I'm currently analysing this graph (with R) :

> summary(g.sw.gcc)
Vertices: 55173
Edges: 2016005
Directed: TRUE
Graph attributes: density, transitivity, clustering, layout.
Vertex attributes: name, membership, degree, size, frame.color, label, color.
Edge attributes: weight, arrow.width, width.

And I've got some problems.

First, is it a good move to save everything as graph attributes as above ?

Secondly, I'd like to plot it. layout.lgl needed around 10 minutes on my computer. The result is saved as an attribute. But when I try to plot the graph, it doesn't work. This is the error message (Translation : impossible to allocate of vector of size 261.5 Mo) :

> plot(g.sw.gcc)
Erreur : impossible d'allouer un vecteur de taille 261.5 Mo
R(720,0xa0a1f500) malloc: *** mmap(size=274178048) failed (error code=12)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug
R(720,0xa0a1f500) malloc: *** mmap(size=274178048) failed (error code=12)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug

What is wrong ? Is this graph too big ? I don't understand why it's trying to use such a big vector. When I save the graph with all its attributes using the save(g.sw.gcc,file="…"), the resulting file weighs only 26.5 Mo.

Thirdly, do you have any recommendations, when using closeness.estimate or betweenness.estimate, in the choice of cutoffs ? Do you know something about a rule depending on the number of vertices and edges and how those indices fluctuate depending on the cutoff value (if you don't I'll check by myself) ? And well, in this case with about 36 edges incident to each vertex, closeness may be useless.


PS : do you know the snap library ( http://snap.stanford.edu/index.html ) developped by Jure Leskovec ? I haven't tried it yet and am wondering if it could be useful for igraph…


Thanks in advance.

Best,

Yannick

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