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Mason,

Thank you so much. Both links point to important material that I was
unaware of. As I replied to James Moody, all I meant by lumpier was that in
this case, the Louvain method produces a few clusters that are double or
triple the size of the clusters produced by the VOS method. If I were to
chart the two distributions, the Louvain distribution would have a few
larger peaks. It looks like the variance is greater to me. I am not a
mathematician or statistician, but I am curious about why these differences
occur. I am aware that different methods are likely to produce different
results, but am interested in this particular case.

Thanks again.

John


On Mon, Aug 5, 2013 at 4:42 PM, Mason Alexander Porter <
[log in to unmask]> wrote:

> *****  To join INSNA, visit http://www.insna.org  *****
>
> John,
>
> I'm not sure what you mean by 'lumpier', but let me just make the generic
> comment that one _expects_ different methods in which a complicated
> optimization landscape is involved to give different results.  There is an
> extensive discussion in the following paper (in the context of modularity
> optimization, including with Louvain):
>
>         http://pre.aps.org/abstract/**PRE/v81/i4/e046106<http://pre.aps.org/abstract/PRE/v81/i4/e046106>
>
>
>
> I have never played with VOS, but in my googling to figure out what that
> is, I found this web page (which seems concerned with rather similar issues
> as what you raise):
>
>         http://mrvar.fdv.uni-lj.si/**pajek/community/LouvainVOS.htm<http://mrvar.fdv.uni-lj.si/pajek/community/LouvainVOS.htm>
>
>
>
> ------
> Mason
>
>
>
>
>
> On Mon, 5 Aug 2013, SOCNET automatic digest system wrote:
>
>  There is 1 message totalling 363 lines in this issue.
>>
>> Topics of the day:
>>
>>  1. Louvain vs VOS Community Detection
>>
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>> ------------------------------**------------------------------**
>> ----------
>>
>> Date:    Mon, 5 Aug 2013 10:58:35 +0900
>> From:    John McCreery <[log in to unmask]>
>> Subject: Louvain vs VOS Community Detection
>>
>> --047d7b5d6592708e4304e329a524
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> *****  To join INSNA, visit http://www.insna.org  *****
>>
>> Two recent runs through part of my data using the Pajek commands for,
>> first, VOS and, second, Louvain community detection. My question is why
>> the
>> results using the Louvain method seem lumpier than those using the VOS
>> method. Note, for example, that cluster 1 in the VOS distribution has 36
>> members, while cluster 1 using the Louvain method has 97. Using the VOS
>> method, cluster 11 has 35 members, while cluster 11 using the Louvain
>> method has 101. Is there a straightforward explanation why the two
>> algorithms produce such apparently different results? Or is this just a
>> random event?
>>
>> Thoughts?
>>
>
>
>
> -----
> Mason
>
> ------------------------------**------------------------------**
> ----------------
>  Mason A. Porter
>  University Lecturer
>  Oxford Centre for Industrial and Applied Mathematics
>  Mathematical Institute, University of Oxford
>
>  Homepage: http://people.maths.ox.ac.uk/**porterm/<http://people.maths.ox.ac.uk/porterm/>
>  Blog: http://masonporter.blogspot.**com/<http://masonporter.blogspot.com/>
>  Twitter: @masonporter
>  Skype: tepid451
>  ------------------------------**------------------------------**
> ----------------
>  "Few things are deadlier than me armed with a red pen." (Me)
>  ------------------------------**------------------------------**
> ----------------
>
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-- 
John McCreery
The Word Works, Ltd., Yokohama, JAPAN
Tel. +81-45-314-9324
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