Fast-greedy is a modularity based method - it works by trying to
build larger and larger communities by adding vertices to each community
one by one and assessing a modularity score at each step. The modularity
score is an index of how inter-connected edges are within versus between
communities. Thanks to the clustering fast greedy method, we can
identify 6 groups, and the modularity index is 0.41.
Community detection II
In contrast, the edge-betweenness is a divisive method - it works by
dividing the network into smaller and smaller pieces until it finds
edges that it perceives to be ‘bridges’ between communities. With the
clustering edge betweenness method, we can identify 18 groups and the
modularity index is 0.39.