On Fri, Jul 12, 2013 at 8:23 AM, <[email protected]> wrote:

> Hello,
> I have encountered following problem in R:
> I construct graph from a matrix of edges, but resulting graph has fewer
> edges than there is rows in the matrix.
>
> # edges are stored in a matrix M
>
> > head(M)
>
>      USEK1 USEK2
> [1,]   985   866
> [2,]   982   866
> [3,]  1062  1039
> [4,]  1088  1119
> [5,]  1061  1088
> [6,]  1060  1061
>
>
> # matrix stores 3244 edges
> > dim(M)
>
> [1] 3244    2
>
>
> # number of vertices
> > max(M)+1
>
> [1] 2404
>
>
> > g <- graph.empty(n=max(M)+1,directed=T)
> > g <- add.edges(g,M)
>

Aer you sure this works? I think it'll just take the matrix as a vector,
column-wise, which is probably not what you want.


> > g
> IGRAPH D--- 2404 3242 --
>
>
> #########
>
>
> there are two edges missing.
>
> Can anyone explain, what it the source of this behavior, and how can I fix it?
>
>
Maybe you have NAs in the matrix and they are ignored. But this is just a
guess, as you did not provide a reproducible example that I could try.
Maybe it is a bug in igraph, although I would say that is unlikely.

Best,
Gabor


>
> Best Regards,
>
> Zbynek Janoska
> Transport Research Centre
> Olomouc, Czech Republic
> [email protected]
>
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