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) :
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
Halld?r
image function with date-time on X axis
3 messages · Halldór Björnsson, Peter Ehlers
On 2010-04-29 12:15, Halld?r Bj?rnsson 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 Halld?r
______________________________________________ R-help at 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.
Peter Ehlers University of Calgary
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 Halld?r
On Fri, Apr 30, 2010 at 2:05 AM, Peter Ehlers <ehlers at ucalgary.ca> wrote:
On 2010-04-29 12:15, Halld?r Bj?rnsson 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 Halld?r
______________________________________________ R-help at 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.
-- Peter Ehlers University of Calgary