[R] Package GSS for interpolation in more than 2D?

[Chong Gu]

Try to use method="u" in ssanova and set varht to a very small number.
Never tried that so am not sure whether it would be numerically
stable.

Chong Gu


   Date: Thu, 2 Aug 2001 21:47:39 +0200 (MET DST)
   From: Kjetil Kjernsmo <kjetil.kjernsmo at astro.uio.no>
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   Dear all,

   There has been some time since I asked about interpolation in higher (>2)
   dimensions, and I must admit I failed to write a function to do this
   myself the last time, but eventually ended up doing it in MATLAB. I tried
   to translate the MATLAB code, but MATLAB code is so much more opaque than
   R (S) code, so I failed that too, mainly because I could only get one
   MATLAB session, I would add... ;-)

   I'm now reviewing the packages, and I was wondering whether gss could do
   what I need? The data I have are not random (at least not very... ;-) ),
   and I really don't need smoothing splines, but I figured, if smoothing
   splines is an extension of normal splines, it might do the job. If it
   can, may I then ask how?

   My problem:
   In the simplest case, I have two data.frames: For each of the data.frames
   The three first coloumns make up a 3D grid (I'd like to go up to at least
   5), and the fourth coloumn contains the values for the point specified in
   the first three.

   The smaller data.frame, may have been generated by e.g.
   expand.grid(ntotalclouds=seq(1000000, 12000000, length=2),
			       EW=seq(8,25,length=3),
			       numberofbins=seq(100, 1000, length=3))
   while the larger data.frame may look like
   argsspacex50 <- expand.grid(ntotalclouds=seq(1000000, 12000000, length=6),
			       EW=seq(8,25,length=6),
			       numberofbins=seq(100, 1000, length=7))
   what I want to do, is simply to interpolate the data in the smaller
   data.frame so that I get a new data.frame where the three first coloumns
   are identical to the larger data.frame and contains interpolated data at
   the corresponding points.

   Any advices?

   Best,

   Kjetil
   -- 
   Kjetil Kjernsmo
   Graduate astronomy-student                    Problems worthy of attack
   University of Oslo, Norway            Prove their worth by hitting back
   E-mail: kjetikj at astro.uio.no                                - Piet Hein
   Homepage <URL:http://folk.uio.no/kjetikj/>
   Webmaster at skepsis.no                            OpenPGP KeyID: 6A6A0BBC



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