Thomas, Thank you for this example, makes it easier to see what levelplot does - does this mean that EVERY time I want to plot with levelplot() I have to not only reverse the columns [,ncol(output.temp):1] but also have to transform the matrix as below? I am only suprised as I don't remember having read about this in the R-info in ?levelplot or R-help website and it seems like a fundamental thing to know if using levelplot!
Thanks, Jenny > > rm(list=ls(all=TRUE)) > graphics.off() > # make a test matrix: > nr<- 3 > nc<- 4 > # the data: > ( m<- matrix((1:(nr*nc)), nr, nc) ) > [,1] [,2] [,3] [,4] > [1,] 1 4 7 10 > [2,] 2 5 8 11 > [3,] 3 6 9 12 > > # the way that levelplot (and image) displays the data: > t(m)[dim(t(m))[1]:1, ] > [,1] [,2] [,3] > [1,] 10 11 12 > [2,] 7 8 9 > [3,] 4 5 6 > [4,] 1 2 3 > > # undo what levelplot does by performing the inverse transformation > inverse<- function(x) t(x[dim(x)[1]:1, ]) > > windows(); levelplot(m, main="levelplot(m)") > windows(); levelplot(inverse(m), main="levelplot(inverse(m))") > > > Message: 7 > > Date: Mon, 11 Dec 2006 12:28:17 +0000 (GMT) > > From: Jenny Barnes <[EMAIL PROTECTED]> > > Subject: [R] upside down image/data > > To: [email protected] > > Message-ID: <[EMAIL PROTECTED]> > > Content-Type: TEXT/plain; charset=us-ascii > > > > Dear R-community, > > > > I am looking for some simple advice - I have a matrix (therefore 2 dimensional) > > of global temperature. > > > > Having read R-help I think that when I ask R to image() or > levelplot() my matrix > > will it actually appear upside down - I think I therefore need to use the line: > > > levelplot(temperature.matrix[,ncol(output.temp):1], ........) > > to get it looking like it was on the globe due to the matrix rows increasing in > > number down the matrix in its dimensions on longitude and latitude > but the > > y-axis coordinates increase up the axis. > > > > Can anyone simply tell me whether this is correct as I find it very hard to know > > which way up my data should be and I cannot tell which is correct simply by > > looking at it! > > > > Many thanks for your time in reading this problem, > > > > Jenny Barnes > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Jennifer Barnes PhD student - long range drought prediction Climate Extremes Department of Space and Climate Physics University College London Holmbury St Mary, Dorking Surrey RH5 6NT 01483 204149 07916 139187 Web: http://climate.mssl.ucl.ac.uk ______________________________________________ [email protected] 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.
