Re: [igraph] combining communities

[Claudia Muller-Birn]

Hi Gabor,

On Aug 9, 2010, at 4:48 PM, Gábor Csárdi wrote:

> On Mon, Aug 9, 2010 at 2:19 PM, Claudia Muller-Birn <address@hidden> wrote:
>> Hi Gabor,
>> 
>> On Aug 9, 2010, at 4:16 AM, Gábor Csárdi wrote:
>> 
>>> Sorry this was not complete yet, I mean
>>> 
>>> g <-  simplify(as.undirected(ba.game(100, 3)))
>>> sc <- spinglass.community(g)$membership
>>> el <- get.edgelist(g)
>>> for (i in seq_len(max(sc)+1)-1) {
>>>  w <- which(sc==i)-1
>>>  el[ el %in% w ] <- w[1]
>>> }
>>> mode(el) <- "character"
>>> el <- unique(el)
>>> graph.edgelist(el, dir=FALSE)
>>> 
>>> You can remove the loop edges before creating the graph:
>>> el <- el[ el[,1] != el[,2], ]
>> 
>> Interesting solution. But unfortunately, I am not experienced enough to 
>> understand every step. Do you mind to extend your code by some comment lines 
>> (starting with the for loop)? That would be great. Thank you very much!
> 
> The loops iterates over the communities. From each community we the
> take the id of the first vertex and replace the ids of all other
> vertices with this one in the edge list.
> 
> The rest is not very important, the "mode(el)" line is needed because
> the vertex ids are not consecutive any more in the edge list matrix
> and thus we want to use them as symbolic vertex names. The "unique"
> line removes the duplicate edges.

Thank you very much. I'll try to apply this for my problems as soon as possible 
:)

Regards,
Claudia

> 
> Best,
> Gabor
> 
>>> Best,
>>> Gabor
>> 
>> Claudia
>> 
>>> 
>>> On Mon, Aug 9, 2010 at 10:07 AM, Gábor Csárdi <address@hidden> wrote:
>>>> Hi,
>>>> 
>>>> in igraph 0.6 we have a function for that (contract.vertices in R),
>>>> but it should not be too hard to code a quick solution in R. E.g.
>>>> 
>>>> g <- erdos.renyi.game(100, 1/100)
>>>> sc <- spinglass.community(g)$membership
>>>> el <- get.edgelist(g)
>>>> for (i in seq_len(max(sc)+1)-1) {
>>>> 
>>>> }
>>>> 
>>>> On Mon, Aug 9, 2010 at 2:33 AM, Stuart Kininmonth
>>>> <address@hidden> wrote:
>>>>> Hi,
>>>>> 
>>>>> just wondering if anyone has written any code to take a community 
>>>>> membership identity list and combine the nodes and arcs to create a 
>>>>> community network?
>>>>> 
>>>>> thanks,
>>>>> 
>>>>> Stuart Kininmonth
>>>>> Spatial Ecologist
>>>>> Australian Institute of Marine Science
>>>>> 
>>>>> 
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>>>> 
>>>> 
>>>> 
>>>> --
>>>> Gabor Csardi <address@hidden>     UNIL DGM
>>>> 
>>> 
>>> 
>>> 
>>> --
>>> Gabor Csardi <address@hidden>     UNIL DGM
>>> 
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> 
> 
> 
> -- 
> Gabor Csardi <address@hidden>     UNIL DGM
> 
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