contour lines on a plot

Hi,

El lun, 19-01-2009 a las 18:37 +0100, Maxime Pauwels escribi?:
  

Dear Virgilio,

I think you're right. Unfortunately, I am not familiar enough with the 
analysis of spatial data to avoid such conflict.
Do you know wath function I should use to generate contour before 
conversion.
    

This example may help:


library(maptools)

res <- ContourLines2SLDF(contourLines(volcano))

grd<-GridTopology(c(0,0), 1/dim(volcano), dim(volcano))
spvolcano<-SpatialGridDataFrame(grd,
data.frame(altitude=as.vector(volcano)))

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

There is something wrong in the way I have defined the grid topology and
the contour lines are shifted north, but you will get the idea. You
could also add labels to the contour lines.

Best,

Virgilio