[igraph] Identifying vertices belonging to fully closed triads in large graph

[Wagner, Stefan]

Dear igraph-list,

 

I am trying to identify all fully closed triads in large directed graphs as well as the vertices belonging to them.

 

I am aware that triad.census provides a count of all fully closed triads. However, I am looking for a way to identify all individual fully closed triads in a graph. Ideally, I get a matrix with 3 columns (for each vertice in a triad) and n lines for the each fully closed triad in my directed graph.

 

I found the following solution in https://stackoverflow.com/questions/40597315/igraph-finding-all-subgraphs-of-specified-shape: Generate all possible combinations of 3 vertices and use sna’s triad.classify to identify the fully closed triads within these combinations. However, the number of different vertices in my graphs is too big, to generate all possible combinations using the combn command. (At least, I get an error message when trying.)

 

Is there an alternative approach?

 

Thanks for your help,

 

Stefan