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

[Kjetil Kjernsmo]

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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