3-d splinefun
Colby,
Function surf() in package labdsv uses the gam() function from mgcv
to do this in conjunction with akima. You might want to look at that
routine for an idea. Currently it fits the gam as z <- gam(s(x) + s(y),
but it's possible in the mgcv version of gam to fit z <- gam(s(x,y)) as
well. The gam function gives a good interpolation with measured error
and appropriate fit statistics.
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Colby Tanner wrote:
hello,
is it possible to do something like splinefun(x,y), but with a 3rd
dim?
for example, if i have a 2-dim system like:
x<-1:100
y<-rexp(100,1)
func<-splinefun(x,sort(y))
func(n) # returns interpolated value of y (after sorting) given x=n
# i can check this by:
plot(x,sort(y))
lines(spline(x,sort(y)))
Can i do the same thing with an x,y, and z? i have found the akima
interp(x,y,z) for building 3-d images, but nothing about the function
aspect. besides building a nice 3-dim image, i would like to have a
way of finding the interpolated z values if i give an x and y
coordinate. something like func(x,y) in the above example.
thank you,
colby
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