Re: [igraph] igraph - get shortest paths and iterators

[Gábor Csárdi]

Stefan,

the not-yet-released 0.6 version has a weighted edge-betweenness
implementation. You can download a source R package from

http://code.google.com/p/igraph/downloads/list

Be careful, because in this version nodes and edges are indexed from 1
and not from 0, so it might be incompatible with your already existing
code.

Best,
Gabor

On Fri, Jan 6, 2012 at 5:44 AM, Blumentrath, Stefan
<address@hidden> wrote:
> Dear all,
>
>
>
> I am using the igraph-package in R quite often for network analysis, and I
> do love it!
>
> In a project I am using it on a network with more than 5500 conservation
> areas (vertices) and up to 1.6 mio edges. Igraph works very well for that
> network-size too.
>
>
>
> There is just one exeption:
>
> “edge.betweenness” does not account for edge-weights. This is why I wrote a
> workaround combining “get.shortest.paths”- and the iterator-function (“E(g,
> path=x)”, to get the edges along the shortest paths).
>
> Unfortunately, the “get.shortest.paths”-function returns always a list
> object (even if called with a single pair of nodes), which the iterator
> function cannot interpret (and which is why I used mclapply in my
> workaround). For smaller networks (mc)lapply did the job good enough. But
> having 5500x5500 possible combinations of vertices makes even mclapply with
> 15 cores impossible.
>
>
>
> My questions are:
>
> Is there any chance to make “edge.betweenness” accounting for edge-weights?
>
> Or is it possible to add (for example) a mode to “get.shortest.path” which
> makes it returning edge-ids instead of vertex-ids?
>
> Or is it possible to generate a function “get.shortest.path” (returning a
> vector of vertex-ids for a single shortest path between a pair of vertices
> (and not a list)? This would make the output directly usable in the
> iterator-function…
>
>
>
> Any help or hints is very much appreciated!
>
>
>
> Many thanks!
>
>
>
> Best regards,
>
> Stefan
>
>
>
>
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>



-- 
Gabor Csardi <address@hidden>     MTA KFKI RMKI