Re: [igraph] how to compare two networks...

[Tamas Nepusz]

Dear Simone,

I think the difference lies between how igraph and sna handles  
multiple edges. Both of your networks have multiple edges. sna  
collapses multiple edges into one single edge and then takes the  
symmetric difference of the two edge sets -- at least that is what I  
assume, since I obtained the same result in Python after doing these  
operations manually on your networks (hdist = 611). Strictly speaking,  
this method is incorrect if there are multiple edges and they have to  
be taken into account. In this sense, the approach described by Gabor  
is better: get the adjacency matrices, take the difference of the two  
matrices, take the absolute value of every element in the difference  
matrix and then sum the elements. This results in a Hamming distance  
of 664. sna simply does not count the cases where there are two edges  
from A to B in one of the networks and only one in the other.

--
T.

On 2008.04.19., at 0:36, Simone Gabbriellini wrote:

> Gabor,
>
> I see the small graphs solution is good for me, it works easy but,  
> compared to hdist in sna package, I have a different results. And  
> even your two solutions bring to different outcomes on the same two  
> networks... it's all about ten/twenty edges more or less:
>
> small graphs: 657
> hdist (sna): 611
> large graphs: 664
>
> I have attached the file for testing, if you have the time.
>
> regards,
> Simone
>
> <simulated-1.net><empirico.net>
>
> > igraph-help mailing list
> > address@hidden
> > http://lists.nongnu.org/mailman/listinfo/igraph-help
>
> _______________________________________________
> igraph-help mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/igraph-help