Re: [igraph] Negative weights in betweenness centrality calculation

[Tamás Nepusz]

> I am wondering how the betweenness centrality calculation work on the
> negative weights values.
Chances are that it won't. Betweenness centrality calculates all the shortest 
paths in the network (where "shortest" means "having smaller total weight") and 
then counts how many times a given edge occurs in shortest paths. If all the 
edges are negative, then there is a very high chance that a negative cycle 
exists in your graph. By traversing a negative cycle many times, one can 
arbitrarily decrease the weight of a path between any two vertices whose path 
passes through this negative cycle.

> In our graph, we all have edges with negative
> weights in which larger value means closer connections.
You have to find a transformation that turns similarity scores like yours into 
distances without introducing negative values. The "correct" transformation 
usually depends on your particular application so there is no single "good" way 
of doing it.

-- 
T.