postscript {grDevices}R Documentation

PostScript Graphics

Description

postscript starts the graphics device driver for producing PostScript graphics.

The auxiliary function ps.options can be used to set and view (if called without arguments) default values for the arguments to postscript.

Usage

postscript(file = ifelse(onefile, "Rplots.ps", "Rplot%03d.ps"),
           onefile = TRUE,
           paper, family, encoding, bg, fg,
           width, height, horizontal, pointsize,
           pagecentre, print.it, command,
           title = "R Graphics Output", fonts = NULL)

ps.options(paper, horizontal, width, height, family, encoding,
           pointsize, bg, fg,
           onefile = TRUE, print.it = FALSE, append = FALSE,
           reset = FALSE, override.check = FALSE)

Arguments

file a character string giving the name of the file. If it is "", the output is piped to the command given by the argument command.
For use with onefile=FALSE give a printf format such as "Rplot%03d.ps" (the default in that case).
paper the size of paper in the printer. The choices are "a4", "letter", "legal" and "executive" (and these can be capitalized). Also, "special" can be used, when the width and height specify the paper size. A further choice is "default", which is the default. If this is selected, the papersize is taken from the option "papersize" if that is set and to "a4" if it is unset or empty.
horizontal the orientation of the printed image, a logical. Defaults to true, that is landscape orientation on paper sizes with width less than height.
width, height the width and height of the graphics region in inches. The default is to use the entire page less a 0.25 inch border on each side.
family the font family to be used. EITHER a single character string OR a character vector of length four or five. See the section ‘Families’.
encoding the name of an encoding file. Defaults to "WinAnsi.enc" in the ‘R_HOME/afm’ directory, which is used if the path does not contain a path separator. An extension ".enc" can be omitted.
pointsize the default point size to be used.
bg the default background color to be used. If "transparent" (or an equivalent specification), no background is painted.
fg the default foreground color to be used.
onefile logical: if true (the default) allow multiple figures in one file. If false, generate a file name containing the page number and use an EPSF header and no DocumentMedia comment.
pagecentre logical: should the device region be centred on the page: defaults to true.
print.it logical: should the file be printed when the device is closed? (This only applies if file is a real file name.)
command the command to be used for “printing”. Defaults to option "printcmd"; this can also be selected as "default".
append logical; currently disregarded; just there for compatibility reasons.
reset, override.check logical arguments passed to check.options. See the Examples.
title title string to embed in the file.
fonts a character vector specifying R graphics (device-independent) font family names for fonts which must be included in the PostScript file.

Details

postscript opens the file file and the PostScript commands needed to plot any graphics requested are stored in that file. This file can then be printed on a suitable device to obtain hard copy.

A postscript plot can be printed via postscript in two ways.

  1. Setting print.it = TRUE causes the command given in argument command to be called with argument "file" when the device is closed. Note that the plot file is not deleted unless command arranges to delete it.
  2. file="" or file="|cmd" can be used to print using a pipe on systems that support ‘popen’. Failure to open the command will probably be reported to the terminal but not to ‘popen’, in which case close the device by dev.off immediately.

Only the first of these will work on Windows, and the default "printcmd" is empty and will give an error if print.it=TRUE is used. Suitable commands to spool a PostScript file to a printer can be found in ‘RedMon’ suite available from http://www.cs.wisc.edu/~ghost/index.html. The command will be run in a minimized window. GSView 4.x provides ‘gsprint.exe’ which may be even more convenient (it requires GhostScript version 6.0 or later).

The postscript produced by R is EPS (Encapsulated PostScript) compatible, and can be included into other documents, e.g., into LaTeX, using \includegraphics{<filename>}. For use in this way you will probably want to set horizontal = FALSE, onefile = FALSE, paper = "special".

Most of the PostScript prologue used is taken from the R character vector .ps.prolog. This is marked in the output, and can be changed by changing that vector. (This is only advisable for PostScript experts: the standard version is in namespace:grDevices.)

ps.options needs to be called before calling postscript, and the default values it sets can be overridden by supplying arguments to postscript.

A PostScript device has a default font, which can be set by the user via family. If other fonts are to be used when drawing to the PostScript device, these must be declared when the device is created via fonts; the font family names for this argument are device-independent R graphics font family names (see the documentation for postscriptFonts).

Line widths as controlled by par(lwd=) are in multiples of 1/96 inch. Multiples less than 1 are allowed. pch="." with cex = 1 corresponds to a square of side 1/72 inch.

Families

Font families may be specified in several ways. The family argument specifies an initial/default font family for the device. This may be a device-independent R graphics font family (see postscriptFonts) or a PostScript-specific font family specification (see below). The fonts argument specifies a set of device-independent font families that are mapped to PostScript-specific fonts via a font database (see postscriptFonts).

The argument family specifies the initial/default font family to be used. In normal use it is one of "AvantGarde", "Bookman", "Courier", "Helvetica", "Helvetica-Narrow", "NewCenturySchoolbook", "Palatino" or "Times", and refers to the standard Adobe PostScript fonts of those names which are included (or cloned) in all common PostScript devices.

Many PostScript emulators (including those based on ghostscript) use the URW equivalents of these fonts, which are "URWGothic", "URWBookman", "NimbusMon", "NimbusSan", "NimbusSanCond", "CenturySch", "URWPalladio" and "NimbusRom" respectively. If your PostScript device is using URW fonts, you will obtain access to more characters and more appropriate metrics by using these names. To make these easier to remember, "URWHelvetica" == "NimbusSan" and "URWTimes" == "NimbusRom" are also supported.

It is also possible to specify family = "ComputerModern". This is intended to use with the Type 1 versions of the TeX CM fonts. It will normally be possible to include such output in TeX or LaTeX provided it is processed with dvips -Ppfb -j0 or the equivalent on your system. (-j0 turns off font subsetting.)

If the second form of argument "family" is used, it should be a character vector of four or five paths to Adobe Font Metric files for the regular, bold, italic, bold italic and (optionally) symbol fonts to be used. If these paths do not contain the file separator, they are taken to refer to files in the R directory ‘R_HOME/afm’. Thus the default Helvetica family can be specified by family = c("hv______.afm", "hvb_____.afm", "hvo_____.afm", "hvbo____.afm", "sy______.afm"). It is the user's responsibility to check that suitable fonts are made available, and that they contain the needed characters when re-encoded. The fontnames used are taken from the FontName fields of the afm files. The software including the PostScript plot file should either embed the font outlines (usually from ‘.pfb’ or ‘.pfa’ files) or use DSC comments to instruct the print spooler to do so.

The .afm files for the first four fonts do not need to be in the correct encoding, but that for the symbol font must be.

When family = "ComputerModern" is used, the italic/bold-italic fonts used are slanted fonts (cmsl10 and cmbxsl10). To use text italic fonts instead, use family = c("CM_regular_10.afm", "CM_boldx_10.afm", "cmti10.afm", "cmbxti10.afm", "CM_symbol_10.afm").

Encodings

Encodings describe which glyphs are used to display the character codes (in the range 0–255). By default R uses ISOLatin1 encoding, and the examples for text are in that encoding. However, the encoding used on machines running R may well be different, and by using the encoding argument the glyphs can be matched to encoding in use.

None of this will matter if only ASCII characters (codes 32–126) are used as all the encodings agree over that range. Some encodings are supersets of ISOLatin1, too. However, if accented and special characters do not come out as you expect, you may need to change the encoding. Three other encodings are supplied with R: "WinAnsi.enc" and "MacRoman.enc" correspond to the encodings normally used on Windows and MacOS (at least by Adobe), and "PDFDoc.enc" is the first 256 characters of the Unicode encoding, the standard for PDF.

If you change the encoding, it is your responsibility to ensure that the PostScript font contains the glyphs used. One issue here is the Euro symbol which is in the WinAnsi and MacRoman encodings but may well not be in the PostScript fonts. (It is in the URW variants; it is not in the supplied Adobe Font Metric files.)

There is one exception. Character 45 ("-") is always set as minus (its value in Adobe ISOLatin1) even though it is hyphen in the other encodings. Hyphen is available as character 173 (octal 0255) in ISOLatin1.

Computer Modern fonts are encoded rather differently and should be used with encoding = "TeXtext.enc", taking care that the symbols < > \ _ { } are not available in those fonts.

Author(s)

Support for Computer Modern fonts is based on a contribution by Brian D'Urso durso@hussle.harvard.edu.

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

postscriptFonts, Devices, {check.options which is called from both ps.options and postscript}.

Examples

## Not run: 
# open the file "foo.ps" for graphics output
postscript("foo.ps")
# produce the desired graph(s)
dev.off()              # turn off the postscript device
options(printcmd='redpr -P"\\markov\lw"')
postscript(file=tempfile("Rps."), print.it=TRUE)
# produce the desired graph(s)
dev.off()              # send plot file to the printer
## alternative using GSView 4.x
options(printcmd='/GhostGum/gsview/gsprint -query')

# for URW PostScript devices
postscript("foo.ps", family = "NimbusSan")

## for inclusion in Computer Modern TeX documents, perhaps
postscript("cm_test.eps", width = 4.0, height = 3.0,
           horizontal = FALSE, onefile = FALSE, paper = "special",
           family = "ComputerModern", encoding = "TeXtext.enc")
## The resultant postscript file can be used by dvips -Ppfb -j0.

## To test out encodings, you can use
TestChars <- function(encoding="ISOLatin1", family="URWHelvetica")
{
    postscript(encoding=encoding, family=family)
    par(pty="s")
    plot(c(-1,16), c(-1,16), type="n", xlab="", ylab="", xaxs="i", yaxs="i")
    title(paste("Centred chars in encoding", encoding))
    grid(17, 17, lty=1)
    for(i in c(32:255)) {
        x <- i 
        y <- i 
        points(x, y, pch=i)
    }
    dev.off()
}
## there will be many warnings.  We use URW to get a complete enough
## set of font metrics.
TestChars()
TestChars("ISOLatin2")
TestChars("WinAnsi")
## End(Not run)


ps.options(bg = "pink")
utils::str(ps.options(reset = TRUE))

### ---- error checking of arguments: ----
ps.options(width=0:12, onefile=0, bg=pi)
# override the check for 'onefile', but not the others:
utils::str(ps.options(width=0:12, onefile=1, bg=pi,
                      override.check = c(FALSE,TRUE,FALSE)))

[Package grDevices version 2.1.0 Index]