Linking, unlinking and relinking a hypernode to a hyperedge will fail

[GoogleCodeExporter]

Steps to reproduce the problem

a = hypergraph()

a.add_nodes([1,2,3])
a.add_edges([4,5])

a.link(3,5)
a.unlink(3,5)
a.link(3,5)

I expected no exception but I got an exception instead

the reason can be easily be seen from the source of hypergraph.py:

    def link(self, node, hyperedge):
        """
        Link given node and hyperedge.

        @type  node: node
        @param node: Node.

        @type  hyperedge: node
        @param hyperedge: Hyperedge.
        """
        if (hyperedge not in self.node_links[node]):
            self.edge_links[hyperedge].append(node)
            self.node_links[node].append(hyperedge)
            self.graph.add_edge(((node,'n'), (hyperedge,'h')))
        else:
            raise AdditionError("Link (%s, %s) already in graph" % (node, hyperedge))

    def unlink(self, node, hyperedge):
        """
        Unlink given node and hyperedge.

        @type  node: node
        @param node: Node.

        @type  hyperedge: hyperedge
        @param hyperedge: Hyperedge.
        """
        self.node_links[node].remove(hyperedge)
        self.edge_links[hyperedge].remove(node)

unlink should have something like:

self.graph.del_edge(((node,'n'), (hyperedge,'h')))

Original issue reported on code.google.com by emanuelez@gmail.com on 1 Feb 2011 at 3:49

[GoogleCodeExporter]

Accepted. Thanks for your report.

Original comment by pmatiello on 1 Feb 2011 at 10:28

• Changed state: Accepted

[GoogleCodeExporter]

Would you be willing to generate a patch & an additional test case? I'd be 
happy to validate & merge in any changes you propose. You can submit your 
changes as a SVN diff if you are familiar with that.

Original comment by s...@stodge.org on 1 Feb 2011 at 11:14

[GoogleCodeExporter]

I can surely generate a patch and add a test case... as for the svn diff I'll 
see what I can do :) I never used SVN before (I only interfaced to an SVN 
server throw Git before).

Will work on it tomorrow. 

Original comment by emanuelez@gmail.com on 1 Feb 2011 at 11:29

[GoogleCodeExporter]

That was easier than I expected so here it is!

Original comment by emanuelez@gmail.com on 1 Feb 2011 at 11:48

Attachments:

• link-unlink-link.diff

[GoogleCodeExporter]

Great, would you also include a unit-test. Ideally it should be nothing more 
than the code you've already found - we just want to show in test-form that the 
formerly broken test is now working. 

Thanks for the diff!

Original comment by s...@stodge.org on 1 Feb 2011 at 11:51

[GoogleCodeExporter]

the diff I provided already includes an additional testcase for 
unittests-hypergraph.py

Original comment by emanuelez@gmail.com on 1 Feb 2011 at 11:53

[GoogleCodeExporter]

Any news on this?

Original comment by emanuelez@gmail.com on 21 Feb 2011 at 12:57

[GoogleCodeExporter]

Maybe other devs are busy at the moment so I took the courtesy and applied your 
patch to trunk after verifying and testing it on my local copy. The patch 
itself was a no-brainer. Thank you for your contribution!

See r726

Original comment by tomaz.ko...@gmail.com on 27 Feb 2011 at 2:26

• Changed state: Fixed

[GoogleCodeExporter]

Thank you Tomaz :)

Original comment by emanuelez@gmail.com on 27 Feb 2011 at 4:40

[GoogleCodeExporter]

emanuelez, can you provide us your first name, last name and email address so 
we can give you credit for the fix?

Original comment by pmatiello on 14 Mar 2011 at 1:27

[GoogleCodeExporter]

Emanuele Zattin, emanuelez@gmail.com

Original comment by emanuelez@gmail.com on 14 Mar 2011 at 1:30

[GoogleCodeExporter]

It's done. Thanks.

Original comment by pmatiello on 14 Mar 2011 at 10:00