Re: [jgrapht-users] EdgeReversedGraph does not modify edgeSet.

[John V. S. <js...@gm...>]

Luis Pureza wrote:
> Hi,
> 
> I have been using JGraphT for some graph related activities and I love 
> it. Nonetheless, I seem to have found an inconsistency.
> 
> When I create an EdgeReversedGraph, the edgeSet() is not reversed. Is 
> this a bug? Would you like me to cook up a patch?

Do you mean you are expecting that when you iterate edgeSet, the edges 
will be E3 E2 E1 if they were E1 E2 E3 in the original graph?  That's 
not a bug; this class only reverses the direction of the edges (not 
their order in the set).

> Also, while I'm at it... I need to be able to tell if two graphs are 
> equal. Is it enough to compare the vertexSet()s and the edgeSet()s of 
> both graphs? If you'd like, I can submit a patch that implements 
> equals() and hashCode() for graphs.

By equal, do you mean isomorphic?  That is the main comparison of 
interest for graphs, but there is no known polynomial-time algorithm for 
it.  We have a brute-force implementation in the experimental package.

JVS