[R-sig-Geo] Too many points for deldir()

[Rolf Turner]

I had a similar query about a month ago, and it appears that the
limitation is intrinsic to R and there's nothing that can be done about
it through modifying deldir.

You are quite right to say that "there will be problems at the
borderlines of blocks".  I would guess that doing such an amalgamation
of triangulations would be a very difficult problem.  It is possible that
there is something about it in the literature; I wouldn't know.

There is another package for doing triangulation on CRAN.  It's called
"tripack".  This package presumably uses a different algorithm from
deldir so it is *possible* that it does not bump up against the same
limitation.  You might want to give it a try.  There is other software
(not written in R) out there for doing triangulation and it is possible
that one of these implementations might alleviate your problem. There
is a "sweepline algorithm" due to Steve Fortune about which I have
seen laudatory comments.

Finally, let me just say that it is mysterious to me what one could
discover from a triangulation/tessellation of 1.3 million points. It seems
to me that any potential information would be lost in a blur of noise.
Why are you doing this?

     cheers,

         Rolf Turner

On 11/05/13 00:05, Ludwig Hilger wrote:
> Hello everybody,
>
> I am trying to construct Thiessenpolygons from a very large dataset (ca. 1.3
> mio points) and get the following error:
>
> thiessen <- deldir(normv$X, normv$Y)
> [...]
> Fehler: lange Vektoren (Argument 7) nicht unterstützt in  .C (~= long
> vectors (argument 7) not supported in .C)
>
> I am wondering if this comes from the number of points and if yes, if there
> is a way to split the dataset into blocks and putting the result back
> together afterwards? I suspect that there will be problems at the
> borderlines of blocks!?