[R-sig-Geo] colour mapping tesselated irregular xy data

Rolf Turner r.turner at auckland.ac.nz
Thu Apr 14 00:08:37 CEST 2011

On 14/04/11 09:48, baptiste auguie wrote:
> Thanks, it is cleaner indeed. However, it's still painfully slow on
> large data sets (typically a couple hundred thousand points). Looking
> at the source of various functions, it looks like the place to look at
> would be deldir::tile.list(). To my naive eyes it doesn't look
> particularly efficient, given that the "meat" of the calculation that
> I expected more costly was performed by deldir() in much less time.

You are very likely correct; tile.list() was an add-on, which was appended
to the deldir package in a rather cobbled-together manner at the request
of a user.  Its functionality probably should be incorporated into the 
process of the basic deldir structure, in the Fortran code.

I've been vaguely thinking about doing something along these lines for a
while.  But this would require that I revive my understanding of the Fortran
code which I wrote lo, these many years ago.  (Like about thirty (!) for the
original pass at the code.)  So it would be a non-trivial undertaking.  
I don't
know when I'll be able to get at it, but it certainly won't be less than 
3 or 4
months from now.

Feel free to nudge me about it, from time to time! :-)


         Rolf Turner

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