Re: [igraph] random walks with directed edges

[Tamás Nepusz]

> are these good indicators that maybe the network has a core-periphery
> structure, with nested k-groups, instead of connected communities with
> some links between them?

Yes, I strongly suspect so.
 
> again, if this is a suitable answer, is there any core-periphery
> algorithm in igraph?

Well, as a first approximation, you can say that nodes with a low coreness 
value are the periphery and the rest is the core. Alternatively, you could say 
that the big strongly connected component is the core and the rest is the 
periphery. You could also try to fit a stochastic blockmodel to the network 
with two groups -- this is not implemented in igraph, but I have a working 
implementation for both traditional and degree-corrected stochastic blockmodel 
fitting in C++ (using igraph) so I can help you with that. The source code is 
here in case you are interested:

https://github.com/ntamas/blockmodel

This paper gives you a short overview about the existing methods in Section 2.1 
and also proposes a new method:

http://www.amath.unc.edu/Faculty/mucha/Reprints/coreperiphery.pdf

Best,
T.