[igraph] Re: Question about community detection

[zhengjun chen]

Hi,

I am using Modularity to evaluate the goodness of community division.

In order to get the largest modularity, a while loop is used to record the modularity value of different "step", which is a parameter of function "igraph_community_leading_eigenvector()". In such way, I record 100 modularity value, and find the largest one corresponding to the "step" value 48. I initialized the membership vector and arpack option parameters for every loop.

However, to verify the result, I set the "step" to 48, and rerun the program (just one time). The modularity value I get this time is different from that obtained by the while loop. I am a bit confused.

 

On Sat, Dec 19, 2009 at 5:13 PM, zhengjun chen <zhjchen.sa@gmail.com> wrote:

Hi,

I have a question about community detection in Igraph."igraph_community_leading_eigenvector()" function is used to detect communities.

My question is what is the meaning of "steps" in this function. Does it mean the number of community split operation?

When I change this value from 10 to 100, more and more communities have been detected. So, the parameter "steps" should be set to what?

In addition, I have no idea about how many communities actually exist. So, what can I do to verify that the communities detected is good enough?

I am also a bit confused of the structure igraph_arpack_options_t. Now I just initialize it to default values. 

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Thanks
zhengjun

Graduate research assistant
Dept of Computer Science and Engineering
Lehigh University

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Thanks
zhengjun

Graduate research assistant
Dept of Computer Science and Engineering
Lehigh University