Thanks a lot Tamas, that makes sense in the end. If I have any bright ideas 
(doubtful...) for graph-level centrality measures for weighted graphs, will 
send them on!


Best,

A


________________________________
From: igraph-help <[email protected]> on 
behalf of Tamas Nepusz <[email protected]>
Sent: Friday, December 30, 2016 9:23 AM
To: Help for igraph users
Subject: Re: [igraph] Graph-level weighted degree, betweeeness, closeness?


However, is the weight edge attribute of the graph automatically detected when 
calculating the graph-level versions of these three metrics?

I guess not because the output seems to be blissfully ignorant of weights:

> g <- make_ring(10)
> centr_betw(g)
$res
 [1] 8 8 8 8 8 8 8 8 8 8

$centralization
[1] 0

$theoretical_max
[1] 324
> E(g)$weight <- c(100, rep(1, 9))
> centr_betw(g)
$res
 [1] 8 8 8 8 8 8 8 8 8 8

$centralization
[1] 0

$theoretical_max
[1] 324

I think the reason is that the graph-level cenrality metrics require the 
"theoretical maximum" of the centrality score across all possible connected 
networks with the same node count, and this is not well-defined for weighted 
graphs (because we don't know what we shall do with the weight -- shall we 
consider all possible permutations of the original weight set, or shall we 
consider weights uniformly distributed within a certain bounded or unbounded 
range?). If you can come up with or show us a formal definition of the 
centralization (i.e. graph-level centrality) score for weighted graphs, maybe 
we can come up with a solution using igraph.

T.
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