Re: [igraph] Counting number of cliques each vertex is in

[Tamás Nepusz]

> I'm trying to count the number of cliques that each vertex is in.  I couldn't 
> find a native igraph function, so I wrote one that works fine using <clique>, 
> but is a bit slow.
> 
> So, my simple question is whether there is a native igraph function that 
> would do the same?
No, there isn't; unfortunately you are on your own here. If you haven't tried 
it yet, take a look at the maximal clique enumeration function 
(igraph_maximal_cliques in C, maximal.cliques in R, Graph.maximal_cliques() in 
Python) and try to make use of the fact that any subgraph of a maximal clique 
is also a clique. So, if you find a maximal clique involving vertex v, it means 
that v is also contained in every subgraph of that clique. Of course this leads 
to another problem: if v is contained by multiple maximal cliques that also 
overlap with each other, you will count every clique that consists of vertices 
in the overlap multiple times, and you have to take this into account. I'm not 
sure whether this is actually simpler in the end or not, but I'm sure that the 
clique enumeration part will take a shorter time.

Best,
Tamas