[R] Setting default graphics device & options

[Henrik Bengtsson]

Hi,

see the R.devices package
[http://cran.r-project.org/web/packages/R.devices/].   FYI, there is a
vignette [R.devices-overview.pdf], but for some reason it's hard find.
 However it is there: help.start() -> R.devices -> 'User guides,
package vignettes and other documentation.' -> R.devices-overview.pdf.

First, don't forget to call library("R.devices").

CREATE IMAGE FILE ATOMICALLY:
To create a PNG image file 'GaussianDensity.png' in subdirectory
figures/ (of the current working directory), do:

toPNG("GaussianDensity", aspectRatio=0.6, scale=2, {
  curve(dnorm, from=-5, to=+5)
})

This will, while still using png()/dev.off() internally, (1)
automatically add filename extension, (2) set the height of the image
as 0.6 times the default width, (3) rescale height and width to be 2
times the default, and (3) make sure the PNG device is closed
afterward (no more forgetting about dev.off()).

It's also make sure not to leave incomplete image files behind in case
there's an error in your plot code.  There's an option to change that
behavior too, e.g. so it instead renames the incomplete file for easy
identification.


DEFAULT OUTPUT DIRECTORY:
You can set the default output directory as:

options("devEval/args/path"="/srv/samba/share/")

Then, whenever you call toPNG(), it will instead save the file to
/srv/samba/share/.  If the directory is missing, it will be created
automatically.


DEFAULT FILENAME:
Currently it is not possible to set a default filename pattern.
However, you can do something like:

imgname <- function() {
  # NOTE: No filename extension
  sprintf("Rplot-%s", format(Sys.time(), "%Y%m%d-%H%M%S"))
}

and then use:

toPNG(imgname(), aspectRatio=0.6, scale=2, {
  curve(dnorm, from=-5, to=+5)
})

(I'll think about adding support for a default image name format).


DEFAULT DEVICE OPTIONS:
To change the default image dimensions, do:

> devOptions("png", width=1280, height=800);

Importantly, in order for these devOptions() to apply, you must use
toPNG() [or devEval("png")]; they won't apply if you call png()
explicitly.  To check the default options, do:

> str(devOptions("png"))
List of 11
 $ filename      : chr "Rplot%03d.png"
 $ units         : chr "px"
 $ pointsize     : num 12
 $ bg            : chr "white"
 $ res           : logi NA
 $ family        : chr "sans"
 $ restoreConsole: logi TRUE
 $ type          : language c("windows", "cairo", "cairo-png")
 $ antialias     : language c("default", "none", "cleartype", "grey", "subpixel"
)
 $ width         : num 1280
 $ height        : num 800

The default "defaults" are inferred from the default in R, so if you
don't change anything you'll get the same output as calling
png()/dev.off().

BTW, unless all of your images should have aspect ratio
800/1280=0.625, I'd recommend to use square defaults (just as the
png() device do), e.g. devOptions("png", width=1280, height=1280), and
then specify aspectRatio=0.625 in your toPNG() calls.


In addition to toPNG(), there are also toBMP(), toEPS(), toPDF(),
toSVG() and toTIFF(), with their own devOptions() settings.


Hope this is useful

Henrik

PS. From your example where all images have the same filename format
with timestamps, it almost looks like you want to do an automatic
log/archiving of image files generated.  If so, I also have the
R.archive package (not yet on CRAN) in development.  All you need to
do is load that package and everything else will be automatic.
Whenever R.devices creates an image file (e.g. via toPNG()), a copy of
it will be saved to ~/.Rarchive/%Y%m%d/%H%M%OS3-<imgname>.<ext>, e.g.
~/.Rarchive/2013-05-26/100330.684_GaussianDensity.png.  For every
toPNG(), toPDF() etc another copy will be created with a unique
filename.  That is useful when you do lots to EDA and want to go back
to that image you did a couple of hours ago.  If this is what you
want, let me know and I'll show you how to get access to R.archive.


On Sun, May 26, 2013 at 8:20 AM, Vishal Belsare <shoot.spam at gmail.com> wrote:
> Hi,
>
> Is it possible to :
>
> [1] set a default location to plot graphs in png format with specific
> dimensions & resolution. I want to plot to a directory which is a shared on
> the network (samba share), so as to view the plots from a different machine.
> prior2plot <- function() {plotfile <-  paste('/srv/samba/share/Rplot-',
> as.character(format(Sys.time(), "%Y%m%d-%H%M%S")), '.png', sep='');
> png(filename=plotfile, width=1280, height=800)}

>
> [2] call dev.off() 'automagically' after a call to the plot function, by
> (somehow) setting it as a default behavior in .Rprofile.site? This would be
> nice to have, so as to update an image viewer running on a local machine
> which keeps displaying the image(s) in the shared plot folder on the remote
> machine (which runs R)
>
> I was thinking on the lines of adding the following to .Rprofile.site :
> __________
>
> prior2plot <- function() {plotfile <-  paste('/srv/samba/share/Rplot-',
> as.character(format(Sys.time(), "%Y%m%d-%H%M%S")), '.png', sep='');
> png(filename=plotfile, width=1280, height=800)}
>
> setHook("before.plot.new", prior2plot())
>
> __________
>
> However, the above does not seem to work beyond a first plot.
>
> Best wishes,
>
> Vishal
>
>         [[alternative HTML version deleted]]
>
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