Thanks Peter zlevs and ylevs are similar, that was not the problem
Following your suggestion I now use > image(tax, ylevs, Rmat, xaxt = "n") > axis.POSIXct(1, at = seq(tax[1],tax[length(tax)],by="1 day"),format="%d-%m") Which does what I wanted to do I still get the warning message, but otherwise this works. Thanks again Halldór On Fri, Apr 30, 2010 at 2:05 AM, Peter Ehlers <[email protected]> wrote: > On 2010-04-29 12:15, Halldór Björnsson wrote: >> >> I am trying to plot a image where the x axis has the units of time. >> When I issue the >> image(x,y,z) command with x as a POSIXct object, it fails to put a >> time stamp on the >> x axis. >> >> Instead I get a warning "Incompatible methods" warning and no dates on >> my x axis. >> >> This example shows my problem: >> >> Rmat=t(matrix(data=rnorm(1:500),ncol=10,nrow=50)) >> tax=seq(ISOdate(2010,4,14,12,0,0), ISOdate(2010,4,19,00,0,0), by = "12 >> hours") ylevs=seq(100,5000,length=50) >> image(tax,ylevs,Rmat) >> >> This givies the warning: >> In image.default(tax, zlevs, Rmat) : >> Incompatible methods ("-.POSIXt", "Ops.difftime") for "-" >> 2: In is.vector(X) : > > I don't get that warning. Are you doing something you're not > telling us? (I note that you have 'ylevs' in one place and 'zlevs' > in another). > > This works for me (using your above definitions of Rmat, etc): > > image(tax, ylevs, Rmat, xaxt = "n") > axis(1, at = as.numeric(tax), lab = weekdays(tax, TRUE)) > > -Peter Ehlers > >> >> Contrast the x axis result of image with that of plot >> plot(tax,rnorm(length(tax))) >> >> where the date-time shows stamps work fine. >> >> How can I get image to behave (or is there a better function for the job?) >> >> Sincerely >> Halldór >> >> ______________________________________________ >> [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. >> >> > > -- > Peter Ehlers > University of Calgary > ______________________________________________ [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.
