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## Re: [igraph] label propagation community

 From: Tamas Nepusz Subject: Re: [igraph] label propagation community Date: Wed, 10 Nov 2010 09:10:37 +0000

```Dear Prof. Freeman,

> This confuses me.  The original method must at least begin at the first step
> by randomly choosing among the uniquely named adjacent and equally weighted
> nodes.
Yes, so does our implementation. But note that nodes are not weighted here,
only the *edges* have weights, and a new label of a node is decided by
weighting the neighbors' labels with the weights of the edges leading to that
neighbor.

For instance, let us assume that node A has three incident edges with weights
1, 2 and 4, and leading to nodes B, C, and D, respectively. Nodes B and C are
"red", node D is "blue". Node A will find that the total weight of edges
leading to red nodes is 1+2=3, while the total weight of edges leading to blue
nodes is 4, hence it will choose "blue" as a new label. The choice is
deterministic unless there are multiple labels with equal total weights. If
there is a tie among the labels with the most total weights, one of them is
chosen randomly. If all the weights are equal, this reduces to the case
described in the paper where the *number* of edges leading to different labels
matters, not the total weight.

I hope this helps.

Regards,
--
Tamas

```