R: PostScript Graphics

postscript {graphics} | 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")

    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`. If it is `"|cmd"`, the output is piped to the command given by ‘`cmd`’. 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 "ISOLatin1.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.

### 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.

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:graphics`.)

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

### Families

The argument `family` specifies the 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.

### 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

`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
    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.

    ## To test out encodings, you can use
    TestChars <- function(encoding="ISOLatin1", family="URWHelvetica")
    {
        postscript(encoding=encoding, family=family)
        par(pty="s")
        plot(c(0,15), c(0,15), type="n", xlab="", ylab="")
        title(paste("Centred chars in encoding", encoding))
        grid(15, 15, 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)))

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