Re: [igraph] Neighors with apply

[Gábor Csárdi]

On Wed, Feb 8, 2012 at 8:45 AM, Thomas <address@hidden> wrote:
> I have a vector with a list of nodes, which does have NAs in it although
> they are always at the end of the list, and I'd like to get a list of all
> the neighbors of those nodes:
>
> dlist <- c(100, 101, 105, NA, NA)
>
> neighbors(g, 100)
> neighbors(g, 101)
> neighbors(g, 105)
>
> is there any way to do this using an apply function? Something like:
>
> sapply(dlist, function(neighbors) neighbors(g,))
> or
> lapply(dlist, neighbors, g)

You can do something like this:

g <- graph.ring(10)
dlist <- c(1,2,3,NA,NA)

lapply(na.omit(dlist), neighbors, graph=g)
lapply(dlist, function(v) if (is.na(v)) NA else neighbors(g, v))

The first version drops the NAs before the neighbors() calls, the
second results NAs for them.

Best,
Gabor

>
> Thank you!
>
> Thomas
>
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-- 
Gabor Csardi <address@hidden>     MTA KFKI RMKI