R help - Oct 2011 - minimizing device-dependent code in graphics scripts

Here is a common scenario that I and probably others often face:

- I write a script, test.R, to produce some graphs, viewing them 
on-screen and tinkering until they look right
- I want to save image files (e.g., .png), so I wrap each plot in device 
driver calls, e.g.,

png(file='test01.png', width=600, height=600);
plot(1:10)
dev.off()

png(file='test02.png', width=600, height=600);
plot(10:1)
dev.off()
...


- Then I want to include those graphs in a document, so maybe I want 
them in .pdf or .eps format.  So I have
to modify all the device calls to pdf() or postscript(), changing the 
filenames and perhaps other options.
If I want those graphs to be squentially numbered with filenames like 
'test%02d' and insert a new graph
in the sequence, I have to edit all the filenames after the insertion.
There has to be an easier way.  (I know I could use Sweave, but that 
introduces another layer that I want to
avoid while I'm developing plots.)

This contrasts strongly with what I've done for many years with SAS:  I 
use *no* device-dependent code in .sas
files, but instead use a collection of device-independent macros that 
respond to a global macro variable, DEVTYP.
On linux, a custom (perl) script sets this as an environment variable 
used by these macros, so I can run test.sas at the
command line via

% alias s=mysas
% s -b -d eps test
% s -d pdf test
% s -v -d png test

and get test1.eps, test2.eps, ... etc. where the basename of the image 
files is automatically set to something
like 'test%01d'.  The -v option opens each of the generated graphics 
files in an appropriate viewer (gs, display, xpdf, etc.)
The -b option for .eps files runs a bbfix script to adjust bounding 
boxes on .eps files.

I don't need anything this elaborate for R, but it's a long way from 
what I do with SAS vs what I do currently with R.
Perhaps other have some partial solutions for this general problem 
they'd be willing to share.

For what it's worth, here is an initial sketch of one approach, using 
two general functions, img() and img.off().
Perhaps others could help improve it.

############  img.R ###################
# shorthand for eps()
eps <- function(file="Rplot.eps", horizontal=FALSE,
paper="special",
height=6, width=6, ...) {
     postscript(file=file, onefile=FALSE, horizontal=horizontal, 
paper=paper, height=height, width=width,...)
   }

img <- function(file, type,
                 height=6, width=6, res=100, units="in", ...) {

     # handle image types
     types <- c("bmp", "eps", "jpg",
"pdf", "png")
     if (missing(type)) {
         if (exists("imgtype")) {
             if (is.null(imgtype)) return() else type <- imgtype
         }
     }
     else {
         t <- match(type, types, nomatch=0)
         if(t > 0) type <- types[t] else stop("unknown file
type")
     }

     if (exists("imgnum") imgnum <<- imgnum+1
     else imgnum <<- 1

# TODO: Handle global imgnum in filename
     if (missing(file)) {
         file <- if(exists("imgname")) paste(imgname,
'%03d', sep='')
else "Rplot%03d"
     }
     filename <- paste(file, '.', type, sep='')
   switch(type,
          bmp = bmp(filename, height=height, width=width, res=res, 
units=units, ...),
          eps = eps(filename, height=height, width=width, ...),
          jpg = jpeg(filename, height=height, width=width, res=res, 
units=units, ...),
          pdf = pdf(filename, height=height, width=width, ...),
          png = png(filename, height=height, width=width, res=res, 
units=units, ...)
          )
}

img.off <- function() {
     if (exists("imgtype") & !is.null(imgtype)) dev.off()
}


TESTME <- FALSE

if(TESTME) {

# set global image name and starting number
imgname <- 'test'
imgnum <- 1
imgtype <- NULL   # screen output

img()
plot(1:10, main=paste("imgtype:", imgtype))
img.off()

imgtype <- "pdf"
img()
plot(10:1, main=paste("imgtype:", imgtype))
img.off()

}




-- 
Michael Friendly     Email: friendly AT yorku DOT ca
Professor, Psychology Dept.
York University      Voice: 416 736-5115 x66249 Fax: 416 736-5814
4700 Keele Street    Web:   http://www.datavis.ca
Toronto, ONT  M3J 1P3 CANADA

On 27/10/2011 10:13 AM, Michael Friendly wrote:
> Here is a common scenario that I and probably others often face:
>
> - I write a script, test.R, to produce some graphs, viewing them
> on-screen and tinkering until they look right
> - I want to save image files (e.g., .png), so I wrap each plot in device
> driver calls, e.g.,
>
> png(file='test01.png', width=600, height=600);
> plot(1:10)
> dev.off()
>
> png(file='test02.png', width=600, height=600);
> plot(10:1)
> dev.off()
> ...
>
>
> - Then I want to include those graphs in a document, so maybe I want
> them in .pdf or .eps format.  So I have
> to modify all the device calls to pdf() or postscript(), changing the
> filenames and perhaps other options.
> If I want those graphs to be squentially numbered with filenames like
> 'test%02d' and insert a new graph
> in the sequence, I have to edit all the filenames after the insertion.
> There has to be an easier way.  (I know I could use Sweave, but that
> introduces another layer that I want to
> avoid while I'm developing plots.)
I use Sweave, more or less as you describe at the top:  I fiddle with 
the graphs on screen first, then when they're fine, I put the code into 
the document.  Mostly the documents use PDF figures, but it's a global 
change at the top if I want something else.  Since all the fiddling is done
on screen, I don't have the issue of Sweave overhead being a problem 
during development (and it's generally pretty low overhead, as long
as I don't put long computations into the documents).

But if I wanted to avoid device calls in scripts, I'd probably do what 
you did below.

Duncan Murdoch
> This contrasts strongly with what I've done for many years with SAS:  I
> use *no* device-dependent code in .sas
> files, but instead use a collection of device-independent macros that
> respond to a global macro variable, DEVTYP.
> On linux, a custom (perl) script sets this as an environment variable
> used by these macros, so I can run test.sas at the
> command line via
>
> % alias s=mysas
> % s -b -d eps test
> % s -d pdf test
> % s -v -d png test
>
> and get test1.eps, test2.eps, ... etc. where the basename of the image
> files is automatically set to something
> like 'test%01d'.  The -v option opens each of the generated
graphics
> files in an appropriate viewer (gs, display, xpdf, etc.)
> The -b option for .eps files runs a bbfix script to adjust bounding
> boxes on .eps files.
>
> I don't need anything this elaborate for R, but it's a long way
from
> what I do with SAS vs what I do currently with R.
> Perhaps other have some partial solutions for this general problem
> they'd be willing to share.
>
> For what it's worth, here is an initial sketch of one approach, using
> two general functions, img() and img.off().
> Perhaps others could help improve it.
>
> ############  img.R ###################
> # shorthand for eps()
> eps<- function(file="Rplot.eps", horizontal=FALSE,
paper="special",
> height=6, width=6, ...) {
>       postscript(file=file, onefile=FALSE, horizontal=horizontal,
> paper=paper, height=height, width=width,...)
>     }
>
> img<- function(file, type,
>                   height=6, width=6, res=100, units="in", ...) {
>
>       # handle image types
>       types<- c("bmp", "eps", "jpg",
"pdf", "png")
>       if (missing(type)) {
>           if (exists("imgtype")) {
>               if (is.null(imgtype)) return() else type<- imgtype
>           }
>       }
>       else {
>           t<- match(type, types, nomatch=0)
>           if(t>  0) type<- types[t] else stop("unknown file
type")
>       }
>
>       if (exists("imgnum") imgnum<<- imgnum+1
>       else imgnum<<- 1
>
> # TODO: Handle global imgnum in filename
>       if (missing(file)) {
>           file<- if(exists("imgname")) paste(imgname,
'%03d', sep='')
> else "Rplot%03d"
>       }
>       filename<- paste(file, '.', type, sep='')
>     switch(type,
>            bmp = bmp(filename, height=height, width=width, res=res,
> units=units, ...),
>            eps = eps(filename, height=height, width=width, ...),
>            jpg = jpeg(filename, height=height, width=width, res=res,
> units=units, ...),
>            pdf = pdf(filename, height=height, width=width, ...),
>            png = png(filename, height=height, width=width, res=res,
> units=units, ...)
>            )
> }
>
> img.off<- function() {
>       if (exists("imgtype")&  !is.null(imgtype)) dev.off()
> }
>
>
> TESTME<- FALSE
>
> if(TESTME) {
>
> # set global image name and starting number
> imgname<- 'test'
> imgnum<- 1
> imgtype<- NULL   # screen output
>
> img()
> plot(1:10, main=paste("imgtype:", imgtype))
> img.off()
>
> imgtype<- "pdf"
> img()
> plot(10:1, main=paste("imgtype:", imgtype))
> img.off()
>
> }
>
>
>
>