[igraph] degree according to vertex attributes

[Dominik Santner (CRIE)]

Hello,

I'm using igraph with R and I have an undirected graph including vertex 
attributes (for example the city of residence). I want to calculate the 
degree separately for connections to actors living in the same city and 
those living in any other city.

Example: John lives in Berlin and has 10 friends (degree of 10). 3 of 
his friends live in Berlin, 3 in Hamburg, 2 in New York and 2 in Munich. 
I need a result telling me that John has 3 friends in the same city and 
7 in any other city.

Thanks

Dominik