I've used a similar three-stage approach. Depending on the format of your map (mine came from an ArcView shape file) you may be able to specify col="transparent" for the foreground (ie land) in plot as I did (tip, use border= to get colours for the country borders). This works where alpha channels don't, such as png. Not sure what image you have, but there may be alternatives, for example, I found .Internal(filledcontour()) extremely useful because then I could explicitly set some of the image to "transparent"... Hth rob
*** Want to know about Britain's birds? Try www.bto.org/birdfacts *** Dr Rob Robinson, Senior Population Biologist British Trust for Ornithology, The Nunnery, Thetford, Norfolk, IP24 2PU Ph: +44 (0)1842 750050 E: [EMAIL PROTECTED] Fx: +44 (0)1842 750030 W: http://www.bto.org ==== "How can anyone be enlightened, when truth is so poorly lit" ===== > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Greg Snow > Sent: 19 February 2008 17:20 > To: Ptit_Bleu; r-help@r-project.org > Subject: Re: [R] how to plot image() without painting a map > (the background) > > The approach that I usually use for things like this is: > > Plot the map to get the aspect ratio and limits correct. > Add the image (obscuring the original map). > Add the map again on top of the image using a light grey color. > > This seems to work fine for me. Another aproach that you may > try (untested) is to use colors with an alpha channel > (transparency) in the call to image, then the background map > may show through. Not all graphics devices support alpha > channels, so test on one that does. > > Hope this helps, > > -- > Gregory (Greg) L. Snow Ph.D. > Statistical Data Center > Intermountain Healthcare > [EMAIL PROTECTED] > (801) 408-8111 > > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Ptit_Bleu > > Sent: Monday, February 18, 2008 8:59 AM > > To: r-help@r-project.org > > Subject: [R] how to plot image() without painting a map (the > > background) > > > > > > Hello, > > > > I'm trying to plot dayly evolution of the temperature over > France from > > Global Forecast System files ("I'm trying" is the right > > expression...). > > > > akilonlat03 is the temperature for different latitudes and > longitudes > > à 3 o'clock. > > akilonlat06 is the temperature for different latitudes and > longitudes > > à 6 o'clock. > > > > I would like to plot akilonlat03 and then akilonlat06 and > keep the map > > of France in background. > > My script (see below) doesn't work as image "paints" the > background as > > I read somewhere in this forum. > > > > So would have someone a solution to correct my script ? > > Thanks in advance, > > Ptit Bleu. > > > > ---------------------------------------------------- > > > > > > akilonlat03<-interp(lonlat03$Longitude, lonlat03$Latitude, > > (5/9)*(lonlat03$TMP_200802150300-32)) > > akilonlat06<-interp(lonlat06$Longitude, lonlat06$Latitude, > > (5/9)*(lonlat06$TMP_200802150600-32)) > > > > map('france') > > > > image(akilonlat03, col=cm.colors(100), axes=FALSE, add=TRUE) > > #contour(akilonlat03, col="blue", add=TRUE) image(akilonlat06, > > col=cm.colors(100), axes=FALSE, add=TRUE) #contour(akilonlat06, > > col="blue", add=TRUE) > > > > -- > > View this message in context: > > http://www.nabble.com/how-to-plot-image%28%29-without-painting > > -a-map-%28the-background%29-tp15546906p15546906.html > > Sent from the R help mailing list archive at Nabble.com. > > > > ______________________________________________ > > R-help@r-project.org 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. > > > > ______________________________________________ > R-help@r-project.org 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. > ______________________________________________ R-help@r-project.org 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.
