igraph (version 0.7.0)

multilevel.community: Finding community structure by multi-level optimization of modularity

Description

This function implements the multi-level modularity optimization algorithm for finding community structure, see references below. It is based on the modularity measure and a hierarchial approach.

Usage

multilevel.community (graph, weights = NULL)

Arguments

graph

The input graph.

weights

Optional positive weight vector. If the graph has a weight edge attribute, then this is used by default. Supply NA here if the graph has a weight edge attribute, but you want to ignore it.

Value

• multilevel.community returns a communities object, please see the communities manual page for details.

concept

• Community structure
• Multilevel community detection

Details

This function implements the multi-level modularity optimization algorithm for finding community structure, see VD Blondel, J-L Guillaume, R Lambiotte and E Lefebvre: Fast unfolding of community hierarchies in large networks, http://arxiv.org/abs/arXiv:0803.0476 for the details.

It is based on the modularity measure and a hierarchial approach. Initially, each vertex is assigned to a community on its own. In every step, vertices are re-assigned to communities in a local, greedy way: each vertex is moved to the community with which it achieves the highest contribution to modularity. When no vertices can be reassigned, each community is considered a vertex on its own, and the process starts again with the merged communities. The process stops when there is only a single vertex left or when the modularity cannot be increased any more in a step. This function was contributed by Tom Gregorovic.

References

Vincent D. Blondel, Jean-Loup Guillaume, Renaud Lambiotte, Etienne Lefebvre: Fast unfolding of communities in large networks. J. Stat. Mech. (2008) P10008

See Also

See communities for extracting the membership, modularity scores, etc. from the results. Other community detection algorithms: walktrap.community, spinglass.community, leading.eigenvector.community, edge.betweenness.community, fastgreedy.community, label.propagation.community

Examples

# This is so simple that we will have only one level
g <- graph.full(5) %du% graph.full(5) %du% graph.full(5)
g <- add.edges(g, c(1,6, 1,11, 6, 11))
multilevel.community(g)