[R] adding custom axis to image.plot() and strange clipping behavior

[Stephen Tucker]

Hi list,

I wanted to plot an image with a colorbar to the right of the plot, but set my 
own axis labels (text rather than numbers) to the image. I have previously 
accomplished this with two calls to image(), but the package 'fields' has a 
wrapper function, image.plot(), which does this task conveniently.

However, I could not add axes to the original image after a call to 
image.plot(); I have found that I needed to set par(xpd=TRUE) within the 
function to allow this to happen:

###=== begin code
library(fields)

## make data matrix
m - matrix(1:15,ncol=3)

## plot
image.plot(m,axes=FALSE)
axis(1) # doesn't work

par(xpd=TRUE)
axis(1) # still doesn't work

## replace the 28th element of the body of image.plot()
## and assign to new function called 'imp'
## here I just use the second condition of 'if' statement
## and set 'xpd = TRUE'
imp - `body-`(image.plot,value=`[[-`(body(image.plot),28,
quote({par(big.par)
  par(plt = big.par$plt, xpd = TRUE)
  par(mfg = mfg.save, new = FALSE)
  invisible()})))
imp(m,axes=FALSE)
box()
axis(1,axTicks(1),lab=letters[1:length(axTicks(1))])
## clip to plotting region for additional
## graphical elements to be added:
par(xpd=FALSE)
abline(v=0.5)
###=== end code

I wonder if anyone has any insights into this behavior? Since in the axis() 
documentation, it says:
Note that xpd is not accepted as clipping is always to the device region
I am surprised to find (1) that the par(xpd=TRUE) works in the case above, and 
(2) that it must be called before the function call is terminated.

I wonder if anyone has any insights into this behavior. I have reproduced this 
on both my Linux box (Ubuntu Gutsy Gibbon 64-bit, R 2.7.0, fields package 
version 4.1) and Windows machine (32-bit XP Pro, R 2.7.0, fields package 
version 4.1).

Thanks very much,

Stephen

__
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.

Re: [R] adding custom axis to image.plot() and strange clipping behavior

[Katharine Mullen]

I also noticed that adding a custom axis with image.plot was a problem;
you can also do:

library(fields)

m - matrix(1:15,ncol=3)

par(mar=c(5,5,5,7))

image(m, axes=FALSE)

# add axis
axis(1,axTicks(1),lab=letters[1:length(axTicks(1))])
box()

## add legend
image.plot(m, legend.only=TRUE)

On Fri, 13 Jun 2008, Stephen Tucker wrote:

 Hi list,

 I wanted to plot an image with a colorbar to the right of the plot, but
 set my own axis labels (text rather than numbers) to the image. I have
 previously accomplished this with two calls to image(), but the package
 'fields' has a wrapper function, image.plot(), which does this task
 conveniently.

 However, I could not add axes to the original image after a call to
 image.plot(); I have found that I needed to set par(xpd=TRUE) within the
 function to allow this to happen:

 ###=== begin code
 library(fields)

 ## make data matrix
 m - matrix(1:15,ncol=3)

 ## plot
 image.plot(m,axes=FALSE)
 axis(1) # doesn't work

 par(xpd=TRUE)
 axis(1) # still doesn't work

 ## replace the 28th element of the body of image.plot()
 ## and assign to new function called 'imp'
 ## here I just use the second condition of 'if' statement
 ## and set 'xpd = TRUE'
 imp - `body-`(image.plot,value=`[[-`(body(image.plot),28,
 quote({par(big.par)
   par(plt = big.par$plt, xpd = TRUE)
   par(mfg = mfg.save, new = FALSE)
   invisible()})))
 imp(m,axes=FALSE)
 box()
 axis(1,axTicks(1),lab=letters[1:length(axTicks(1))])
 ## clip to plotting region for additional
 ## graphical elements to be added:
 par(xpd=FALSE)
 abline(v=0.5)
 ###=== end code

 I wonder if anyone has any insights into this behavior? Since in the axis() 
 documentation, it says:
 Note that xpd is not accepted as clipping is always to the device region
 I am surprised to find (1) that the par(xpd=TRUE) works in the case above, 
 and (2) that it must be called before the function call is terminated.

 I wonder if anyone has any insights into this behavior. I have reproduced 
 this on both my Linux box (Ubuntu Gutsy Gibbon 64-bit, R 2.7.0, fields 
 package version 4.1) and Windows machine (32-bit XP Pro, R 2.7.0, fields 
 package version 4.1).

 Thanks very much,

 Stephen

 __
 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.