[Nauty] canonical label for directed graphs

Gordon Royle gordon at csse.uwa.edu.au
Wed Aug 3 22:23:56 EST 2005

nauty already computes canonical labellings for directed graphs....   
there is no need to modify the algorithm.

However the default settings for the "options" structure is to have  
options.digraph set to FALSE - presumably because some speed can be  
gained if the algorithm can rely on the input being undirected  
without actually confirming that edge j-i is present when it notices  
edge i-j.

So, just set options.digraph = TRUE before your call to nauty, and it  
will treat it as a directed graph


On 03/08/2005, at 7:46 PM, Edward N Turner wrote:

> Dear all,
> Nauty currently allows us to find canonical labels for undirected  
> graphs
> - would it be possible to modify the algorithm it uses to obtain
> canonical labels for directed graphs?

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