[R] Understanding mod.matrix for directed networks

Aziz, Muhammad Fayez aziz4 at illinois.edu
Tue May 19 07:50:09 CEST 2015

Dear Gabor,

Please find attached an Excel file with detailed information on a four node directed network to calculate its pairwise modularity matrix using igraph: mod.matrix(). I have tried multiple combinations to figure out how the formula works or is applied but failed to find consistency, specially for the pairs of arcs in opposing directions where the pairwise modularity is different (highlighted and color-coded). I gave membership(wtc) as input to mod.matrix() but not even sure if its used in the formula provided in the following R manual page:


Advice with a solved example in the Excel sheet would be deeply appreciated.

Thanks and regards,


University of Illinois at Urbana Champaign, USA

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