Re: [igraph] Alpha Centrality Function Crashes

[Judd Antin]

Gabor,

Thanks for the suggestion. That may be a little beyond my abilities. 
It's easy enough for me to get an edgelist, and I can see roughly which 
equation I'll need to solve. However, I'm not sure of how to coerce the 
edgelist into a sparse matrix, nor how exactly to use the sparse matrix 
solver.

Any help is greatly appreciated!

--Judd



Gabor Csardi wrote:
> Judd, 
>
> I get
>
> > g <- erdos.renyi.game(40000, 90000, type="gnm")
> > alpha.centrality(g)
> Error in get.adjacency(graph) : 
>   At vector.pmt:408 : cannot reserve space for vector, Out of memory
>
> Yes, this function uses an adjacency matrix, so you cannot use it
> on such a big graph. You can try the 'Matrix' package. 
> See the code of 'alpha.centrality', get the edge list of 
> the graph with 'get.edgelist', convert it to a (sparse) Matrix,
> and solve the equation with the sparse matrix solver.
> It should not be too difficult, i can help you if you need help.
>
> Gabor
>
> On Thu, Apr 24, 2008 at 08:37:10AM -0700, Judd Antin wrote:
> > Hi all,
> >
> > I've been using igraph in R to look at a a very large, sparse directed 
> > network of about 58,000 nodes and 87,000 edges. I am interested in 
> > calculating alpha centrality scores, but the alpha.centrality function 
> > crashes R for me instantaneously. I've tried this on both Windows and 
> > Mac builds of the library (in case of a platform dependent issue), with 
> > the same results.
> >
> > Does anyone have any insight on how I could get this to work? Is the 
> > size of the network simply too large? I also noticed in the manual that 
> > 'singular adjacency matrices' can cause problems for the algorithm, but 
> > I'm not sure what a 'singular adjacency matrix' is.
> >
> > Any advice appreciated.
> >
> > Thanks!
> >
> > --Judd
> >
> > --
> > Judd Antin
> > School of Information
> > University of California Berkeley
> > address@hidden
> > web: http://technotaste.com
> > blog: http://technotaste.com/blog
> >
> >
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