Although not an R solution, I would highly recommend the generic mapping tools GMT for this type of work.
http://gmt.soest.hawaii.edu/ Cheers, Dylan On Monday 13 September 2010, Craig Stanton wrote: > Hello all, > I'm very new to R and am having some trouble with the results of the > interp function. I'm trying to produce a chart roughly akin to a weather > map with natural looking filled contours over a large region of the south > pacific. I've got a list of points and values to be mapped to those points > and I use the interp function as follows: > > tab<-read.table("data.txt") > library("akima") > png("contour.png", width = 1000, height=500) > colourRange<-colorRampPalette(c("#f9cd00","#f9cd00","#f9cd00","#f9cd00","#f >fffff","#6afaff","#53a3ff","#53a3ff","#53a3ff")) > filled.contour(interp(x=tab$V1,tab$V2, tab$V3, xo=seq(min(tab$V1), > max(tab$V1),length=1000),yo=seq(min(tab$V2), max(tab$V2),length=500), > linear = FALSE), xlim = range(160,190),ylim = range(-30,-10), > zlim=c(-4,4),color.palette = colourRange ) dev.off() > rm(list = ls()) > > > > I have added the "rm(list=ls())" on the end to try to reset the workspace > because I've found that repeated running of this code can result in > different output images. The main problem I am having is that though my > values are all between -2.5 and 2.5 the interpolation gives me values well > outside that range. Usually shown by colouring the areas white but > confirmed by plotting a regular contour map instead of a filled contour. > What I'd like to find out is if there is a way to dampen the cubic spline > that is being used, or if there is an alternative to interp() that I should > be looking at. Like I said before, I'm very new to R, so I may have missed > something entirely obvious. > > Thanks in advance, > Craig > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html and provide commented, minimal, > self-contained, reproducible code. -- Dylan Beaudette Soil Resource Laboratory http://casoilresource.lawr.ucdavis.edu/ University of California at Davis 530.754.7341 ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
