[R] Delaunay Graph, once again

Rolf Turner r.turner at auckland.ac.nz
Tue Jun 24 02:08:15 CEST 2014

On 24/06/14 06:24, Raphael Päbst wrote:

> I have the same suspicion, unfortunately I am no Matlab-User either
> and only have a adjacency-matrix created by the corresponding matlab
> functions to compare with my own output. So, even though I don't see
> any use for collinear triples either, is there a way to get them with
> deldir as well?

Uh, no. Fortune fortune(228) springs to mind here.



> On 6/21/14, Rolf Turner <r.turner at auckland.ac.nz> wrote:
>> You are almost surely being bitten by the issue about which you
>> previously made inquiries to me, concerning the delaunayn() function
>> from the "geometry" package.  (NOTE: ***PACKAGE***!!!  Not "library".  A
>> library is a *collection* of packages.) The delaunayn()
>> function also uses the qhull algorithm.  By default it treats some
>> triples of *collinear* points as triangles.  This is probably causing
>> the discrepancy between the results.
>> Ergo it would seem best to use deldir() unless you *really want*
>> collinear triples to be considered as triangles --- and I can't see why
>> you would.


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