OK, looking into this a bit more it's definitely a PEBCAK error - I misremembered the definition of connected graph. I was confused because G.is_connected() was returning True (it seems like is_connected should really only be used for undirected graphs). I guess I can implement the method I really want by using something along the lines of max(filter(lambda x: x != Infinity, G.eccentricity())).
Thanks! On Sunday, January 11, 2015 at 5:02:10 PM UTC-7, David Joyner wrote: > > On Sun, Jan 11, 2015 at 5:49 PM, Andrew Russell > <[email protected] <javascript:>> wrote: > > I'm running Sage 6.4.1 on OS X (Yosemite). Creating a finite, connected > DAG > > with n vertices (for any n that I tried) returned +Infinity. EG: > > > > sage: digraphs.Path(10).diameter() > > +Infinity > > > > or even > > > > sage: digraphs.ButterflyGraph(5).diameter() > > +Infinity > > > > However, both of these Path and Butterfly graphs are finite, connected, > > directed acyclic graphs so their diameter should always be finite. I > need > > to be able to compute the largest diameter of the connected components > of > > any finite DAG, yet the diameter method fails even on these simple > cases. > > > > Seems to me to work as documented (using Gamma.diameter? or > Gamma.diameter??): > > sage: Gamma = digraphs.Path(3) > sage: Gamma.diameter() > +Infinity > sage: Gamma.eccentricity(0) > 2 > sage: Gamma.eccentricity(1) > +Infinity > sage: Gamma = digraphs.Circuit(3) > sage: Gamma.diameter() > 2 > sage: Gamma.eccentricity(0) > 2 > sage: Gamma.eccentricity(1) > 2 > sage: Gamma.eccentricity(2) > 2 > > > > -- > > You received this message because you are subscribed to the Google > Groups > > "sage-support" group. > > To unsubscribe from this group and stop receiving emails from it, send > an > > email to [email protected] <javascript:>. > > To post to this group, send email to [email protected] > <javascript:>. > > Visit this group at http://groups.google.com/group/sage-support. > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
