Re: [igraph] problems with parameters in barabasi.game()

[Csardi Gabor]

On Wed, Sep 10, 2008 at 04:22:19PM +0200, Mario Lavezzi wrote:
> Hello Gabor
> thank you so much.
> 
> I think I got confused by the different notation used in the papers I am 
> considering at the moment.
> >It is still not the formula in the Dorogovtsev paper, though. I don't 
> >know why, maybe they don't consider multiple edges, or the results are 
> >only valid in some limit.
> >  
> I think that things are a little different because, they actually allow 
> multiple (directed) links, consider a parameter of "attractiveness" of a 
> node which is only initial (and so it is not used at each time step as 
> the "zero.appeal" value, as I understand).
> 
> One last question: can you suggest a quick way of generating degree 
> sequences with a given power-law exponent to  be used  in  the  
> "degree.sequence.game"?

Mario, I would try 'sample' first, e.g. 

degs <- sample(1:1000, 1000, replace=TRUE, prob=(1:1000)^-2)
g <- degree.sequence.game(degs, method="vl")

Note that it is not always possible to realize a given degree sequence,
e.g. if the sum of degrees is odd, then it is trivially impossible.

G.

> >If you just want to have graphs with various power law degree 
> >distributions,
> >you might consider using 'degree.sequence.game', with method="vl", here
> >you can prescribe the exact degree distribution. It always generated 
> >connected graphs, but probably this is not a problem.
> >
> >  
> Thanks a lot!
> best,
> Mario
> 

-- 
Csardi Gabor <address@hidden>    MTA RMKI, ELTE TTK