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

 From: Simone Gabbriellini Subject: Re: [igraph] how to compare two networks... Date: Sun, 20 Apr 2008 23:54:22 +0200

```Tamas,

```
yes you are right!!!! and in my case multiple links do matter!!! I knew it was better to stick to igraph! ;)
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last question: I have one empirical network and 100 simulated networks... any hints on how to evaluate the significance of all Hamming distances to the empirical net? Something like QAP test...
```
many thanks,

Simone

Il giorno 19/apr/08, alle ore 00:53, Tamas Nepusz ha scritto:

```
```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:

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```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>

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```

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