Re: [igraph] how to "collapse" a network

On Thu, Mar 8, 2012 at 4:02 PM, Wet Bell Diver <address@hidden> wrote:

Thanks Gabor, that works well.
--Peter

Op 7-3-2012 19:00, Gábor Csárdi schreef:

Peter,

you can download a 0.6 windows binary R package here:
http://win-builder.r-project.org/Zh7vo2amfgck/

Best,
Gabor

On Wed, Mar 7, 2012 at 7:36 AM, Wet Bell Diver<address@hidden> wrote:

Dear Tamás and Jeremy,

Thanks for your help, both solutions (=the code) work wonderfully.

For the solution using igraph directly, I am having trouble installing it
into my windows (win7, x64) setup, as the both the command line (R INSTALL
etc...) and install.packages("igraph_nightly_0.6-2646-20120229.tar.gz", type
= "source") give me the error: "ERROR: configuration failed for package
'igraph'"
That is a pity, perhaps you have a solution?

Apart from that, the code you provide does the trick as well, and I am
grateful for that.

best,
Peter

Op 6-3-2012 10:36, Tamás Nepusz schreef:

Hello Peter,

It happens frequently that the same companies engage in multiple deals
together, but each deal is represented by a line in my data. As a
result, you see that 'COMP 1' -- 'COMP 2' occurs twice.
I would like to be able to collapse this to a weighted edge list where
'COMP 1' -- 'COMP 2' occurs only once but with value 2, 'COMP 1' --
'COMP 3' occurs only once having value 3, et cetera.
There must be a very simple way of doing this, but how?
I assume that you are using igraph from R. The "simplify" function in
igraph 0.6 will sum up numeric edge attributes when it eliminates multiple
edges, so I guess the easiest for you is to upgrade to the development
version of igraph (that is, 0.6). Since it has not been released officially
yet, you can download it from the page of our nightly builds:

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

Download the latest "GNU R source package", and install it in R. If you
happen to use Windows and need a pre-compiled package, let us know - Gabor
can probably prepare one for you.

Unfortunately if you cannot upgrade to igraph 0.6 for any reason, then the
only option is to use count.multiple to find the "multiplicity" of each
edge, and then construct a new graph manually; e.g., like this (not sure if
there is a simpler solution):

mul<- count.multiple(g)
df<- as.data.frame(get.edgelist(g))
df$weight<- cm
g<- graph.data.frame(unique(df))

Second, each company has several attributes, including industry. One of
the things I would like to do is to collapse the entire
company*company network into a weigted industry*industry network. This
would reduce the network from approx. 2000*2000 to 40*40.
How can I construct such a weighted network in igraph?
igraph 0.6 will also have a function called contract.vertices which lets
you contract many vertices into a single one, so you could proceed by first
contracting the vertices by industry using contract.vertices, followed by
simplify.

--
T.

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From:	P S Das
Subject:	Re: [igraph] how to "collapse" a network
Date:	Tue, 20 Mar 2012 16:34:36 +0530