>>>>> "Hisaji" == Hisaji Ono <[EMAIL PROTECTED]>
>>>>> on Fri, 15 Aug 2003 08:31:34 +0900 writes:
Hisaji> Hi, Kris.
>> Dear,
>>
>> I have XYZ data available in a MySQL database. I get it out, can plot
>> the data with the plot() function, load it into a geoR datastructure.
>> But what I actually would like to do is a simple contouring of the data
>> based on a no Kriging interpolation such as TIN based.
>>
>> I know the first thing I shold do is interpolate a full matrix for the
>> region I have my points for, then contour should do its work. Any idea
>> which function can be used for XYZ interpolations, maybe/hopefully based
>> on a Delaunay triangulation in combination with linear or spline
>> interpolation. Is there a package that allows me to do this?
>>
Hisaji> I found following URL. It's an example for S-PLUS, so you might need some
Hisaji> modifications.
Hisaji> http://geography.uoregon.edu/courses/geog414f01/lectures/lec10.htm
Hisaji> I hope this would help you.
Thank you!
Note that one of the more sophisticated solutions there uses
Akima(1978)'s polynomial interpolation scheme, function
interp() in S-plus.
R's "akima" package interp() function can do a bit more and uses
bivariate spline-interpolation {as in Akima(1996)} by default
(thanks to Albrecht Gebhardt <[EMAIL PROTECTED]>
In short:
## if needed, get the CRAN package "akima"
install.packages("akima")
library(akima)
help(interp)
## now use interp():
intxyz <- interp(x,y,z)
with(zreg, contour(x,y,z))
Martin Maechler <[EMAIL PROTECTED]> http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum LEO C16 Leonhardstr. 27
ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND
phone: x-41-1-632-3408 fax: ...-1228 <><
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