[igraph] Edge weights and community detection

[R N]

Hi *,

I have a weighted graph where the edge weights have only two values:
either w1 or
w2. I noticed that some algorithms are sensitive to the actual values
of w1, w2, while
others seem to be not. Do the community detection algorithms do any
normalization,
scaling of the edge weights or smth before the actual detection, or
just use the supplied
weigths? My questions (assuming a graph with only 2 values of edge weights):
1) Are the CD algorithms supposed to be sensitive to the actual
weights w1, w2, or to their
ratio w2/w1?
2) How are the edges with weight=0 treated -- no connection between
the respective vertices
at all, or some (weak) connection is still assumed?
3) If there are many possible values of edge weights in a graph, would
some scaling (i.e., multiplying
all edge weights by a constant factor) affect the community detection results?

I ask this because 1) probably, one has to select a proper
normalization of edge weights when producing a graph;
2) maybe, the results might be improved by tuning the weights appropriately.