Recently, I've been looking into *motifs* in networks (directed graphs) -- small connected induced subgraphs that appear significantly more frequently than in a "similar random graph".

In practice, we need to enumerate the induced subgraphs (up to isomorphism) in thousands of large random networks, which can take a long time, and requires some form of canonical labelling (e.g. FANMOD uses nauty). My feeling is that nauty is quite bulky and seems likely to be overkill for this feature because e.g. we only need to canonically label small graphs (in FANMOD they have at most 8 vertices -- although I haven't seen much interest in motifs with more than 4 vertices).

Question: Is there a package that specialises in the canonical labelling of small directed graphs?

In the case I'm interested in, we need to label millions of graphs on a small number of vertices.