Re: [igraph] Less vertices in output than input

[Gábor Csárdi]

On Fri, May 3, 2013 at 10:34 AM, Laurens Rietveld <address@hidden> wrote:

Hi Gabor,

Thanks for replying. I can provide an example, though it is quite big (~3GB): http://aers.data2semantics.org/input.tsv

I've tried smaller graphs to reproduce this issue with, but couldnt find any. 

Well, try to make this file smaller, and see if the error stays. I.e. remove the first half of the lines from the file, then remove the first 3/4, etc.

I will try to get this into pajek format, though it'll be some work. I'd hope to avoid this as much as possible (I have bigger graphs around 130GB as well..). 

You can avoid it, but then you'll need to specify the number of vertices explicitly. 

If I understand correctly, the number of isolates might be an issue here? Thing is, when I take a look at my graph, I'm sure some of the vertices have incoming edges. However, when I calculate the indegree, some of these vertices are still missing..

My _guess_ is that it is not possible to know the number of vertices from your edge list file. But you still haven't sent any code, so this is a guess only. Please try sending a smaller data set if you can, and definitely some code that reproduces the problem. 

G.

 

Best, Laurens

On Fri, May 3, 2013 at 3:47 PM, Gábor Csárdi <address@hidden> wrote:

You need to send us a complete example that reproduces a problem. Most probably you have isolate vertices, and from an edge list file format it is sometimes not possible to know how many isolates you have. Use another file format, like Pajek, that is almost the same as an edge list, but specified the number of vertices explicitly.

Gabor

On Fri, May 3, 2013 at 9:12 AM, Laurens Rietveld <address@hidden> wrote:

I'm running igraph to do some experiments, and for some graphs I notice the number of vertices in the analysis output table (e.g. the output of evcent (graph, directed = FALSE)) is less than the vertices used as input (edge list). 

Because this only happens for some typical graphs (quite disconnected), I'm assuming this occurs because there is no weight assigned to this vertice (i.e. value zero). Is this true? Or is something else going wrong here?

Many thanks,

Laurens

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Gabor Csardi <address@hidden>     MTA KFKI RMKI

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Gabor Csardi <address@hidden>     MTA KFKI RMKI