\Header{postscript}{PostScript Graphics}
\alias{.PostScript.Options}{postscript}
\alias{.ps.prolog}{postscript}
\alias{ps.options}{postscript}
\keyword{device}{postscript}
\begin{Description}\relax
\code{postscript} starts the graphics device driver for producing
PostScript graphics.

The auxiliary function \code{ps.options} can be used to set and view
(if called without arguments) default values for the arguments to
\code{postscript}.\end{Description}
\begin{Usage}
\begin{verbatim}
postscript(file = ifelse(onefile, "Rplots.ps", "Rplot%03d.ps"),
           onefile = TRUE,
           paper, family, encoding, bg, fg,
           width, height, horizontal, pointsize,
           pagecentre, print.it, command)

ps.options(paper, horizontal, width, height, family, encoding,
           pointsize, bg, fg,
           onefile = TRUE, print.it = FALSE, append = FALSE,
           reset = FALSE, override.check = FALSE)
.PostScript.Options
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{file}] a character string giving the name of the file.  If it is
\code{""}, the output is piped to the command given by
the argument \code{command}.
If it is \code{"|cmd"}, the output is piped to the command given
by \file{cmd}.

For use with \code{onefile=FALSE} give a \code{printf} format such
as \code{"Rplot\%d.ps"} (the default in that case).

\item[\code{...}] further options for \code{postscript()}.
\item[\code{paper}] the size of paper in the printer.  The choices are
\code{"a4"}, \code{"letter"}, \code{"legal"} and
\code{"executive"} (and these can be capitalized).
Also, \code{"special"} can be used, when the \code{width}
and \code{height} specify the paper size.  A further choice is
\code{"default"}, which is the default.  If this is selected, the
papersize is taken from the option \code{"papersize"}
if that is set and to \code{"a4"} if it is unset or empty.
\item[\code{horizontal}] the orientation of the printed image, a
logical. Defaults to true, that is landscape orientation.
\item[\code{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.
\item[\code{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'.
\item[\code{encoding}] the name of an encoding file. Defaults to
"ISOLatin1.enc"
in the \file{R\_HOME/afm} directory, which is used
if the path does not contain a path separator.  An extension
\code{".enc"} can be omitted.
\item[\code{pointsize}] the default point size to be used.
\item[\code{bg}] the default background color to be used. If "white" (or a
specification equivalent to white), no background is painted.
\item[\code{fg}] the default foreground color to be used.
\item[\code{onefile}] logical: if true (the default) allow multiple figures
in one file. If false, generate a
file name containing the page number and give EPSF header
and no \code{DocumentMedia} comment.
\item[\code{pagecentre}] logical: should the device region be centred on the page:
defaults to true.
\item[\code{print.it}] logical: should the file be printed when the device is
closed?  (This only applies if \code{file} is a real file name.)
\item[\code{command}] the command to be used for ``printing''. Defaults to
option \code{"printcmd"}; this can also be selected as \code{"default"}.
\item[\code{append}] logical; currently \bold{disregarded}; just there for
compatibility reasons.
\item[\code{reset, override.check}] logical arguments passed to
\code{\Link{check.options}}.  See the Examples.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
\code{postscript} opens the file \code{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 \code{postscript} in two ways.
\Enumerate{
\item Setting \code{print.it = TRUE} causes the command given in
argument \code{command} to be called with argument \code{"file"}
when the device is closed.
Note that the plot file is not deleted unless command arranges to
delete it.

\item \code{file=""} or \code{file="|cmd"} can be used to print
using a pipe on systems that support \file{popen}.
}

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

Most of the PostScript prologue used is taken from the \R{} character
vector \code{.ps.prolog}.  This is marked in the output, and can be
changed by changing that vector.  (This is only advisable for
PostScript experts.)

As ISOLatin1 encoding is used, \code{-} is set as a minus and not
as a hyphen.  Supply a hyphen (character 173) if that is what you
need.

\code{ps.options} needs to be called before calling \code{postscript},
and the default values it sets can be overridden by supplying
arguments to \code{postscript}.\end{Details}
\begin{Section}{Families}
The argument \code{family} specifies the font family to be used.
In normal use it is one of \code{"AvantGarde"},
\code{"Bookman"}, \code{"Courier"}, \code{"Helvetica"},
\code{"Helvetica-Narrow"}, \code{"NewCenturySchoolbook"},
\code{"Palatino"} or \code{"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
\code{ghostscript}) use the URW equivalents of these fonts, which are
\code{"URWGothic"}, \code{"URWBookman"}, \code{"NimbusMon"},
\code{"NimbusSan"}, \code{"NimbusSanCond"}, \code{"CenturySch"},
\code{"URWPalladio"} and \code{"NimbusRom"} respectively.  If your
PostScript device is using URW fonts, you will obtain access to more
characters and more approriate metrics by using these names.  To make
these easier to remember, \code{"URWHelvetica" == "NimbusSan"} and
\code{"URWTimes" == "NimbusRom"} are also supported.

It is also possible to specify \code{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 \code{dvips -Ppfb -j0} or the equivalent
on your system. (\code{-j0} turns off font subsetting.)

If the second form of argument \code{"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 \file{R\_HOME/afm}.  Thus the
default Helvetica family can be specified by \code{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
\code{FontName} fields of the \code{afm} files.  The software
including the PostScript plot file should either embed the font
outlines (usually from \code{.pfb} or \code{.pfa} files) or
use DSC comments to instruct the print spooler to do so.\end{Section}
\begin{Section}{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 \code{\Link{text}} are in that encoding.  However,
the encoding used on machines running \R{} may well be different, and by
using the \code{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:
\code{"WinAnsi.enc"} and \code{"MacRoman.enc"} correspond to the
encodings normally used on Windows and MacOS (at least by Adobe), and
\code{"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 (\code{"-"}) 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.\end{Section}
\begin{Author}\relax
Support for Computer Modern fonts is based on a contribution by
Brian D'Urso \email{durso@hussle.harvard.edu}.\end{Author}
\begin{SeeAlso}\relax
\code{\Link{Devices}},
{\code{\Link{check.options}} which is called from both
\code{ps.options} and \code{postscript}}.\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}

# open the file "foo.ps" for graphics output
postscript("foo.ps")
# produce the desired graph(s)
dev.off()              # turn off the postscript device
postscript("|lp -dlw")
# produce the desired graph(s)
dev.off()              # plot will appear on printer

# 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")
## The resultant postscript file can be used by dvips -Ppfb -j0.



stopifnot(unlist(ps.options()) == unlist(.PostScript.Options))
ps.options(bg = "pink")
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:
str(ps.options(width=0:12, onefile=1, bg=pi,
               override.check = c(FALSE,TRUE,FALSE)))
\end{ExampleCode}
\end{Examples}

