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John,

I get SOCnet as a daily digest (which, sometimes, is necessary for my 
sanity) and hadn't yet seen Jim's response.  My bad for not checking 
before asking what you meant.

Louvain's large clusters might well arise in part because of modularity's 
"resolution limit".  Again, I cannot comment relative to VOS because I 
don't have experience with the latter method.

-----
Mason


On Mon, 5 Aug 2013, John McCreery wrote:

> 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)
>>  ------------------------------**------------------------------**
>> ----------------
>>
>> ______________________________**______________________________**_________
>> SOCNET is a service of INSNA, the professional association for social
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>
>
>
> -- 
> John McCreery
> The Word Works, Ltd., Yokohama, JAPAN
> Tel. +81-45-314-9324
> [log in to unmask]
> http://www.wordworks.jp/
>

-----
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/
  Blog: http://masonporter.blogspot.com/
  Twitter: @masonporter
  Skype: tepid451
  ----------------------------------------------------------------------------
  "Few things are deadlier than me armed with a red pen." (Me)
  ----------------------------------------------------------------------------

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