Re: [jgrapht-users] DirectedGraph equality testing

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

For multigraphs, e1 and e2 may both have source v1 and target v2, and yet
they are two distinct edges.

In general, "equality" for a graph isn't a very useful concept due to the
fact that g1 and g2 may be isomorphic even though !g1.equals(g2).


On Wed, Aug 12, 2015 at 2:30 PM, Aidan Delaney <
ai...@on...> wrote:

> Dear all,
>         I've been trying to test for deep vertex & edge equality in a
> DirectedGraph.  An example is below.  It appears that this fails
> because, I think, DefaultEdge needs a non-default hashCode
> implementation.  My GitHub pull-request is at [1], but it causes more
> problems than it solves.
>
> Am I just incorrect in trying to use JGraphT in this way to check graph
> equality?  Is there some other way I should be doing this?
>
> DirectedGraph<String, DefaultEdge> g1 =
>             new SimpleDirectedGraph<String,
> DefaultEdge>(DefaultEdge.class);
>         DirectedGraph<String, DefaultEdge> g2 =
>             new SimpleDirectedGraph<String,
> DefaultEdge>(DefaultEdge.class);
>
>         g1.addVertex("A");
>         g2.addVertex("A");
>
>         assertEquals(g1, g2);
>
>         g1.addVertex("B");
>         g2.addVertex("B");
>
>         assertEquals(g1, g2);
>
> [1] https://github.com/jgrapht/jgrapht/pull/148
>
> --
> Dr Aidan Delaney
> Principal Lecturer
> Computing, Engineering & Maths
> University of Brighton
>
> @aidandelaney
>
>
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