Thank you, that explains it all. I didn't know that it would create an undirected graph by default.
And sorry about the trouble of having to guess. My code to read a data set and create the adj and cost matrices is a bit too lengthy to post here. So I thought some inline comments would give enough information about what is happening on my side. In any case, now I understand what is going on. Thank you very much! Regards, Ram On Sat, Jul 19, 2014 at 3:15 AM, Tamás Nepusz <[email protected]> wrote: > Hello, > > Unfortunately your example is not self-contained (i.e. I cannot run it > straight away without having to make up some artificial input) so I can > only guess at this point. Could it simply be the case that there exists a > pair of nodes A and B such that A is one of the k nearest neighbors of B > and vice versa? In this case, you would obviously have a mutual edge pair > between nodes A and B -- but since your graph is undirected, this edge pair > simply appears as two undirected edges. > > -- > T. > > -----Original Message----- > From: Ram MS <[email protected]> > Reply: Help for igraph users <[email protected]>> > Date: 18 July 2014 at 07:58:27 > To: [email protected] <[email protected]>> > Subject: [igraph] Unwanted multiple edges between vertices > > > Hi, > > > > I am creating an instance of igraph in Python and adding some vertices > and > > edges using add_vertices and add_edges methods of the Graph object. All > the > > vertices and edges are created in one go. I have a 'name' attribute on > the > > vertices and a 'weight' attribute on the edges. Strangely, I am observing > > multiple edges added between some vertices with the same weight. > > > > Currently I am calling graph.simplify() to remove the unwanted multiple > > edges after the graph is constructed. But I am wondering why it is > creating > > multiple edges at all. Could someone help me see what might be going on? > > > > Thanks, > > Ram > > _______________________________________________ > > igraph-help mailing list > > [email protected] > > https://lists.nongnu.org/mailman/listinfo/igraph-help > > > >
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