Hi Simon, On Tue, Jan 25, 2011 at 03:45:35AM -0800, Simon King wrote: > I just noticed that DiGraph produces graphs that are mutable. Is there > any alternative implementation of digraphs (with multiple edges) in > Sage that are immutable?
This is an often requested feature. Please open a ticket! See e.g.: http://groups.google.com/group/sage-combinat-devel/browse_thread/thread/211a073fe1e7f3d8/ Actually, I once needed it so badly, that I hacked a quick workaround. And it inadvertently went into Sage as part of another patch (oops, shame on me and on the reviewer!). So now you can do: sage: G = digraphs.DeBruijn(5,0) sage: hash(G) Traceback (most recent call last): ... TypeError: graphs are mutable, and thus not hashable sage: G._immutable = True sage: hash(G) -3360383311399787762 Please have a look at G.__hash__. To be used at your own risk; there is absolutely no safety; in particular nothing prevents you from changing the graph with all the bad consequences that could occur. Cheers, Nicolas -- Nicolas M. Thiéry "Isil" <nthi...@users.sf.net> http://Nicolas.Thiery.name/ -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
