contour lines on a plot

Hi,
El lun, 19-01-2009 a las 22:19 +0100, Jos? Manuel Blanco Moreno
escribi?:

Just a doubt... there seems that the contours are not shifted but 
"mirrored" (flipped) along an horizontal line?

Very well spotted!!

The right code should be as follows (the change is in the definition of
'spvolcano'):

library(maptools)

x <- 10*1:nrow(volcano)
y <- 10*1:ncol(volcano)
clv<-contourLines(x, y, volcano)

res <- ContourLines2SLDF(clv)

grd<-GridTopology(c(0,0), c(10, 10), dim(volcano))
spvolcano<-SpatialGridDataFrame(grd, 
   data.frame(altitude=as.vector((volcano[,ncol(volcano):1]))))

spplot(spvolcano, sp.layout=list(list("sp.lines", res)) )



Best,

Virgilio