Thank you. Do you know what is an efficient way of getting these
non-isomorphic graphs with n edges?
Using your answer. I can use nauty_geng(2 * n), and then filter out all the
graphs with n edges. But even going through nauty_geng(2*n) is more memory
and spaces needed.
On Tuesday, January 31, 2023 at 6:49:03 AM UTC-5 dim...@gmail.com wrote:
> On Tue, Jan 31, 2023 at 2:38 AM Shiyue Li wrote:
> >
> > Hi all,
> >
> > I am hoping to generate a list of all graph isomorphism classes of a
> given size. The current code that I have first generate all the graphs on
> 2n, and then take all the isomorphism class representatives of size n. But
> the first step of generating all graphs on 2n vertices can take a really
> long time and huge amount of memory (run 10 days on my university's
> research computing cloud) and crashes.
> >
> > See the following for my code:
> >
> > def iso_graphs(n):
> > '''returns all isomorphism classes of simple graphs on n edges on 2*n
> vertices'''
> > L = list(graphs(2 * n, loops=False, size=n)) print("Do we ever reach
> this point?")
> > L = [G.canonical_label().copy(immutable=True) for G in L if G.size() ==
> n]
> > return L
> >
> > I wonder if what is a correct and efficient way of doing it.
>
> We have a function to do this job very efficently:
>
> graphs.nauty_geng()
>
> it generates non-isomorphic graphs. E.g. list(graphs.nauty_geng("3
> -c")) gives you the complete list
> (of lengh 2) of all non-isomrphic connected graphs on 3 vertices
> (remove "-c" there if you want all graphs,
> not only connected)
>
> HTH
> Dima
>
> >
> > Thanks!
> >
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