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## Re: [igraph] Number of isolated nodes in the network

 From: Claudia Muller-Birn Subject: Re: [igraph] Number of isolated nodes in the network Date: Thu, 5 Aug 2010 11:55:45 -0400

```Hi Jordi,

Thank you, this was very helpful :) I had exactly the same idea and a minute
later your email arrived. Perfect timing.

Maybe this solution helps others as well, but be aware of loops! For example in
my networks I had to simplify the graph first:

g <- simplify(g, remove.multiple = TRUE, remove.loops = TRUE)

Otherwise, loops are considered and therefore, the degree is higher than zero.

Thanks again.

Have a great day.

Claudia

On Aug 5, 2010, at 10:56 AM, jordi torrents wrote:

> Hi Claudia,
>
> 2010/8/5 Claudia Muller-Birn:
>> Dear all,
>>
>> I might have a fairly simple question but I have difficulties to solve my
>> problem this time.
>> I'd like to compute the number of isolates nodes in a network. [...]
>
> The function below gives you a vector with the ids of nodes with
> degree 0 (ie isolates):
>
> isolates <- function(g){
>  return(which(degree(g)==0)-1)
> }
>
> i <- isolates(g)
> length(i)
>
> Hope this helps.
> Salut!
>
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```