Hi, A model gives me as output a netCDF file which I read with ncdf package. The output consists of three similar matrices: one contains the variable value, and the other two, the longitude and latitude coordinates. I need to do a contour graph with such information, however, the R contour function expects, two vectors X, Y, and a matrix Z, as its input. X and Y, being the same length as the number of rows and columns of Z matrix, respectively. This implies that the Z values in the same row, all have the same abscissa, and the Z values in the same colum, all have the same ordinate. I know, in systems similar to matlab, ferret, ncl, and the like, you just give the three matrices, and the system performs all the necessary interpolations to display the contour. Do you know if there is a way to do the same in R? Though not exactly an output in a netCDF, I'm presenting here a very simplified example of the kind of output I need to plot. val <- matrix(c(rep(15,5),rep(c(15:17,16,15),2),rep(15,5)),nrow=4,byrow=T) v1 <- 1:5 v2 <- 10:13 xx <- cbind(v2, v2+.1, v2+.2, v2+.1, v2) yy <- rbind(v1, v1+0.1, v1+0.2, v1+0.1) val: is the matrix with the values I want to plot. xx: is the corresponding abscissa values. yy: is the corresponging ordinate values. Thanks, -Sergio.