Re: [igraph] Circular Reingold Tilford on tree is not planar!?

[Robert Belleman]

Hi Gabor, Tamás,

Thanks for your answers.

So it is not possible to derive a circular planar layout from the
RT layout?

Because surely it must be possible to construct a planar circular
layout for any tree?

Do you know an alternative?

Thanks,
-- Rob

Tamás Nepusz wrote:
> > it should be planar, AFAIK. If it is not planar, that means that the
> > original non-circular one is not planar
> No, it isn't necesarily planar. A while ago I found a graph for which
> the RT layout was planar but the circular RT layout wasn't, and I also
> thought it was a bug, but it isn't. Try this graph for instance (given
> as an edge list):
>
> 0-1, 0-2, 0-3, 0-4, 0-5, 0-6, 0-7, 0-8, 0-9, 4-10, 9-10
>
> When you use vertex 0 as root, the RT layout is planar but the circular
> RT layout isn't.
>
> --
> T.
>
> > , the circular one is just the
> > transformation of that. Can you send us (in private if it's big, to
> > Tamas and me) an example? I think this is a bug.
> >
> > Best,
> > Gabor
> >
> > On Fri, Jun 24, 2011 at 9:55 AM, Robert Belleman <address@hidden
> > <mailto:address@hidden>> wrote:
> > > Hi,
> > >
> > > I am applying the circular Reingold Tilford layout algorithm on a tree
> > > consisting of 23k nodes and the same number of edges. I was expecting
> > > this
> > > algorithm to produce a planar layout but it doesn't.
> > >
> > > Can anybody enlighten me?
> > >
> > > Thanks,
> > > -- Rob
> > >
> > > --
> > > Robert Belleman, PhD, Computational Science, Faculty of Science
> > > Universiteit van Amsterdam, Science Park 904, 1098 XH Amsterdam
> > > The Netherlands. T: +31 20 525 7272/7463 F: +31 20 525 7490
> > > W: http://www.science.uva.nl/~robbel/ E: address@hidden
> > > <mailto:address@hidden>
> > >
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> >
> >
> >
> > --
> > Gabor Csardi <address@hidden <mailto:address@hidden>> MTA
> > KFKI RMKI
> >
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