# load the data:
source("/home/longa/www/Rweb/examples/illdat.splus")

# we need the interpolation library:
library("akima")

# we now interpolate the liver cancer variable
liver <- interp(illdat$easting,illdat$northing,illdat$liver)
persp(liver,scale=F)
title(main="Liver Cancer in Illinois, as viewed from the South")

par(mfrow = c(1,2), oma = c(0,0,5,0))
plot(illdat$northing,illdat$easting,main="data locations",xlab="easting",ylab="northing") 

image(liver$y,liver$x,t(liver$z),main="Interpolated via image",xlab="easting",ylab="northing")  
points(illdat$northing,illdat$easting)

# contour(liver$x,liver$y,liver$z,add=T)
# - hangs on NA values, for some reason
# liver$z[!is.finite(liver$z)] <-  mean(illdat$liver)
# this would "fix" it, but is undesirable....

r.ak <- sapply(liver, function(x) diff(range(x,na.rm = T)))
par(mfrow = c(1,2), oma = c(0,0,5,0))
persp(liver, phi=62,scale=F)
persp(liver, theta=45, phi=62,scale=F)
par(mfrow = c(1,1), oma = c(0,0,5,0))
title(main="Liver Cancer in Illinois?")

par(mfrow = c(1,2), oma = c(0,0,5,0))
persp(liver, theta=90, phi=62,scale=F)
persp(liver, theta=135, phi=62,scale=F)
par(mfrow = c(1,1), oma = c(0,0,5,0))
title(main="Liver Cancer in Illinois?")