I guess something like

ends(E(g)[ label == value ])[1]

Would do it. There is also head_of and tail_of but they are mixed up in the
current version. :(
Gabor

On Tue, Jun 30, 2015 at 12:09 AM, Matt <[email protected]> wrote:

> Hi Gabor,
>
> Thank you very much for your prompt answer.
>
> What can I do in case I need to get the first vertex of a specific
> edge, depending on a label that I set for that edge?
> For example I have a graph g whose edges have a label, "label" and I
> want to select the first vertex of all these edges.
>
> For selecting the edge I can use the following:
>
> edges = E(g)[which(E(g)$label == value)]
>
> But afterwords? How can I get the first vertex too?
>
> Thank you again.
>
> Best Regards.
>
> Matt
>
> On Mon, Jun 29, 2015 at 7:49 PM, Gábor Csárdi <[email protected]>
> wrote:
> > Hi Matt. In the new version it is called ends(). G.
> >
> > library(igraph)
> > g <- make_ring(10)
> >
> > ends(g, 1)
> > #>      [,1] [,2]
> > #> [1,]    1    2
> >
> > ends(g, 3)
> > #>      [,1] [,2]
> > #> [1,]    3    4
> >
> >
> >
> > On Mon, Jun 29, 2015 at 7:30 PM, Matt <[email protected]> wrote:
> >>
> >> Dear All,
> >>
> >> If I have an edges, is there a way to get its vertices?
> >>
> >> Thank you very much.
> >>
> >> Best regards.
> >>
> >> Matt
> >>
> >> _______________________________________________
> >> igraph-help mailing list
> >> [email protected]
> >> https://lists.nongnu.org/mailman/listinfo/igraph-help
> >
> >
> >
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> >
>
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