Re: [igraph] warning message in eigen_centrality() function of package igraph

[Tamas Nepusz]

Hello,

>   At centrality.c:362 :Weighted directed graph in eigenvector centrality"
This warning is emitted because weighted directed graphs can introduce
all sorts of complications with the eigenvector calculation. (To be
honest, some of these complications are present even with non-weighted
directed graphs):

- Directed acyclic graphs will have an all-zero eigenvector centrality vector.
- Directed graphs with negative weights may have eigenvector
centrality vectors with complex members - in this case, igraph will
report the real part only.
- If a vertex is not in a strongly connected component of size at
least 2, or in the out-component of such a component, then its
eigenvector centrality will be zero.

If you are sure that your graph does not have these issues, then it is
fine to use the eigenvector centrality. Otherwise, I would recommend
using the PageRank instead as it is better suited for directed graphs.

T.