[igraph] Negative eigenvector centrality?

[Nathan Cobb]

I'm working with a series of large, sparse communication networks
(v~7-15,00;e~10-30,000) The networks are initially directed but not
weighted.

Using iGraph 0.52 with the Python interface I'm getting back negative
Eigenvector centrality scores no matter what I do. The code looks something
like:

target_graph.add_vertices(len(vertices))
target_graph = target_graph.add_edges(edges)
target_graph.to_undirected()
target_graph.simplify(multiple=False,loops=True)
eigenvector_centrality = target_graph.eigenvector_centrality(scale=False)

The resulting values seem to range somewhere between -1 and 0 (never
positive.)

Am I missing something conceptually here, or am I hitting a bug?

Thanks,

- Nate


Nathan Cobb, MD | Research Investigator 
T 202-454-5745  F 202-454-5785 
Schroeder Institute for Tobacco Research and Policy Studies
American Legacy Foundation
1724 Massachusetts Avenue, NW, Washington, DC 20036