R: PDF Graphics Device

pdf {grDevices} | R Documentation

## PDF Graphics Device

### Description

`pdf` starts the graphics device driver for producing PDF graphics.

### Usage

    pdf(file = ifelse(onefile, "Rplots.pdf", "Rplot%03d.pdf"),
        width = 6, height = 6, onefile = TRUE, family = "Helvetica",
        title = "R Graphics Output", fonts = NULL, version = "1.1",
        paper = "special", encoding, bg, fg, pointsize, pagecentre)

### Arguments

`file` | a character string giving the name of the file. For use with `onefile=FALSE` give a C integer format such as `"Rplot%03d.pdf"` (the default in that case). (See `postscript` for further details.)
`width, height` | the width and height of the graphics region in inches.
`onefile` | logical: if true (the default) allow multiple figures in one file. If false, generate a file name containing the page number for each page.
`family` | the font family to be used, see `postscript`.
`title` | title string to embed as the `/Title` field in the file.
`fonts` | a character vector specifying R graphics font family names for fonts which will be included in the PDF file.
`version` | a string describing the PDF version that will be required to view the output. This is a minimum, and will be increased (with a warning) if necessary.
`paper` | the target paper size. The choices are `"a4"`, `"letter"`, `"legal"` (or `"us"`) and `"executive"` (and these can be capitalized), or `"a4r"` and `"USr"` for rotated (‘landscape’). The default is `"special"`, which means that the `width` and `height` specify the paper size. A further choice is `"default"`; if this is selected, the papersize is taken from the option `"papersize"` if that is set and as `"a4"` if it is unset or empty.
`encoding` | the name of an encoding file. See `postscript` for details. Defaults to to the setting given by `ps.options()`, which defaults to `"default"`.
`bg` | the default background color to be used. Defaults to the setting given by `ps.options()`, which defaults to `"transparent"`.
`fg` | the default foreground color to be used. Defaults to to the setting given by `ps.options()`, which defaults to `"black"`.
`pointsize` | the default point size to be used. Strictly speaking, in bp, that is 1/72 of an inch, but approximately in points. Defaults to the setting given by `ps.options()`, which defaults to `12`.
`pagecentre` | logical: should the device region be centred on the page? – is only relevant for `paper != "special"`. Defaults to the setting given by `ps.options()`, which defaults to true.

### Details

`pdf()` opens the file `file` and the PDF commands needed to plot any graphics requested are sent to that file.

The `file` argument is interpreted as a C integer format as used by `sprintf`, with integer argument the page number. The default gives files ‘Rplot001.pdf’, ..., ‘Rplot999.pdf’, ‘Rplot1000.pdf’, ....

The `family` argument can be used to specify a PDF-specific font family as the initial/default font for the device.

If a device-independent R graphics font family is specified (e.g., via `par(family=)` in the graphics package), the PDF device makes use of the PostScript font mappings to convert the R graphics font family to a PDF-specific font family description. (See the documentation for `pdfFonts`.)

R does not embed fonts in the PDF file, so it is only straightforward to use mappings to the font families that can be assumed to be available in any PDF viewer: `"Times"` (equivalently `"serif"`), `"Helvetica"` (equivalently `"sans"`), `"Courier"` (equivalently `"mono"`) and `"Symbol"` (equivalently `"symbol"`). Other families may be specified, but it is the user's responsibility to ensure that these fonts are available on the system and third-party software, e.g., Ghostscript, may be required to embed the fonts so that the PDF can be included in other documents (e.g., LaTeX): see `embedFonts`. The URW-based families described for `postscript` can be used with viewers set up to use URW fonts, which is usual with those based on `xpdf` or Ghostscript. Since `embedFonts` makes use of Ghostscript, it should be able to embed the URW-based families for use with other viewers.

See `postscript` for details of encodings, as the internal code is shared between the drivers. The native PDF encoding is given in file ‘PDFDoc.enc’.

`pdf` writes uncompressed PDF. It is primarily intended for producing PDF graphics for inclusion in other documents, and PDF-includers such as `pdftex` are usually able to handle compression.

The PDF produced is fairly simple, with each page being represented as a single stream. The R graphics model does not distinguish graphics objects at the level of the driver interface.

The `version` argument declares the version of PDF that gets produced. The version must be at least 1.4 for semi-transparent output to be understood, and at least 1.3 if CID fonts are to be used: if these features are used the version number will be increased (with a warning). Specifying a low version number (as the default) is useful if you want to produce PDF output that can be viewed on older or non-Adobe PDF viewers. (PDF 1.4 requires Acrobat 5 or later.)

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, which is also the ‘pixel’ size assumed for graphics parameters such as `"cra"`.

The `paper` argument sets the `/MediaBox` entry in the file, which defaults to `width` by `height`. If it is set to something other than `"special"`, a device region of the specified size is (by default) centred on the rectangle given by the paper size: if either `width` or `height` is less than `0.1` or too large to give a total margin of 0.5 inch, it is reset to the corresponding paper dimension minus 0.5. Thus if you want the default behaviour of `postscript` use `pdf(paper="a4r", width=0, height=0)` to centre the device region on a landscape A4 page with 0.25 inch margins.

### Note

Acrobat Reader does not use the fonts specified but rather emulates them from multiple-master fonts. This can be seen in imprecise centering of characters, for example the multiply and divide signs in Helvetica. This can be circumvented by embedding fonts where possible.

Acrobat Reader 5.x and later can be extended by support for Asian and (so-called) Central European fonts (the latter only for 7.x and later, part of the ‘Extended’ pack for 8.x), and this will be needed for the full use of encodings other than Latin-1. See http://www.adobe.com/products/acrobat/acrrasianfontpack.html.

### See Also

`pdfFonts`, `embedFonts`, `Devices`, `postscript`

More details of font families and encodings and especially handling text in a non-Latin-1 encoding and embedding fonts can be found in

Paul Murrell and Brian Ripley (2006) Non-standard fonts in PostScript and PDF graphics. R News, 6(2):41–47. http://cran.r-project.org/doc/Rnews/Rnews_2006-2.pdf.

### Examples

    ## Not run:
    ## Test function for encodings
    TestChars <- function(encoding="ISOLatin1", ...)
    {
        pdf(encoding=encoding, ...)
        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 %% 16
            y <- i %/% 16
            points(x, y, pch=i)
        }
        dev.off()
    }
    ## there will be many warnings.
    TestChars("ISOLatin2")
    ## this does not view properly in older viewers.
    TestChars("ISOLatin2", family="URWHelvetica")
    ## works well for viewing in gs-based viewers, and often in xpdf.
    ## End(Not run)

[Package grDevices version 2.6.2 Index]