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## Re: [igraph] extracting vertex attributes from an family of graphs

 From: Gábor Csárdi Subject: Re: [igraph] extracting vertex attributes from an family of graphs Date: Thu, 10 Apr 2014 20:52:15 -0400

Yes, but the second can be written as get.vertex.attribute(g, attr, id), which is a lot more readable and it i also slightly faster.

Gabor

On Thu, Apr 10, 2014 at 5:35 PM, Bob Pap wrote:
Many thanks dear Gabor. I think the following two should do (equivalent?)

1. function(g,id="identifierXX",attr="betweeness") {
get.vertex.attribute(g,attr)[which(V(g)\$name==id)]
}

2. function(g,id="identifierXX",attr="betweeness") {
get.vertex.attribute(g,attr,V(g)[which(V(g)\$name==id)])
}

Kindly,
Bob Pap

On 10 April 2014 18:45, Gábor Csárdi wrote:
On Thu, Apr 10, 2014 at 12:31 PM, Bob Pap wrote:
Dear all,

Unaware of any method for dealing with multigraphs (in my case a family of graphs "g" indexed by time), I handle these by creating a list, indexed by the time period, say "Mygraphs", where Mygraphs[["2014-01-01"]] returns graph g as it was in 2014-01-01.

I face the need to extract a combination of attributes from the series (in the example below the vertex's "id" and "betweeness", ordered by the index of Mygraphs), I do so for example as follows:

sapply(
Mygraphs,
function(g,id="identifierXX",attr="betweeness") {
get.vertex.attribute(induced.subgraph(g, which(V(g)\$name==id)),attr)
}
)

I cannot help to think that the use of induced.subgraph could be obviated by specifying the 2 dimensions (id and attr) at once in the extraction, but I how would I restrict get.vertex.attribute to only return the value for vertex "identifierXX" only?

See the 'index' argument of 'get.vertex.attribute'.

Gabor

Any guidance would be appreciated.
Kindly,
Bob Pap

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