text: Add Text to a Plot

Description

text draws the strings given in the vector labels at the coordinates given by x and y. y may be missing since xy.coords(x, y) is used for construction of the coordinates.

Usage

text(x, …)
# S3 method for default
text (x, y = NULL, labels = seq_along(x$x), adj = NULL,
     pos = NULL, offset = 0.5, vfont = NULL,
     cex = 1, col = NULL, font = NULL, …)

Arguments

x, y

numeric vectors of coordinates where the text labels should be written. If the length of x and y differs, the shorter one is recycled.

labels

a character vector or expression specifying the text to be written. An attempt is made to coerce other language objects (names and calls) to expressions, and vectors and other classed objects to character vectors by as.character. If labels is longer than x and y, the coordinates are recycled to the length of labels.

adj

one or two values in \([0, 1]\) which specify the x (and optionally y) adjustment (‘justification’) of the labels, with 0 for left/bottom, 1 for right/top, and 0.5 for centered. On most devices values outside \([0, 1]\) will also work. See below.

pos

a position specifier for the text. If specified this overrides any adj value given. Values of 1, 2, 3 and 4, respectively indicate positions below, to the left of, above and to the right of the specified (x,y) coordinates.

offset

when pos is specified, this value controls the distance (‘offset’) of the text label from the specified coordinate in fractions of a character width.

vfont

NULL for the current font family, or a character vector of length 2 for Hershey vector fonts. The first element of the vector selects a typeface and the second element selects a style. Ignored if labels is an expression.

cex

numeric character expansion factor; multiplied by par("cex") yields the final character size. NULL and NA are equivalent to 1.0.

col, font

the color and (if vfont = NULL) font to be used, possibly vectors. These default to the values of the global graphical parameters in par().

…

further graphical parameters (from par), such as srt, family and xpd.

Euro symbol

The Euro symbol may not be available in older fonts. In current versions of Adobe symbol fonts it is character 160, so text(x, y, "\xA0", font = 5) may work. People using Western European locales on Unix-alikes can probably select ISO-8895-15 (Latin-9) which has the Euro as character 165: this can also be used for postscript and pdf. It is \u20ac in Unicode, which can be used in UTF-8 locales.

The Euro should be rendered correctly by X11 in UTF-8 locales, but the corresponding single-byte encoding in postscript and pdf will need to be selected as ISOLatin9.enc (and the font will need to contain the Euro glyph, which for example older printers may not).

In all the European Windows encodings the Euro is symbol 128 and \u20ac will work in all locales: however not all fonts will include it. It is not in the symbol font used for windows and related devices, including the Windows printer.

Details

labels must be of type character or expression (or be coercible to such a type). In the latter case, quite a bit of mathematical notation is available such as sub- and superscripts, greek letters, fractions, etc.

adj allows adjustment of the text position with respect to (x, y). Values of 0, 0.5, and 1 specify that (x, y) should align with the left/bottom, middle and right/top of the text, respectively. The default is for centered text, i.e., adj = c(0.5, NA). Accurate vertical centering needs character metric information on individual characters which is only available on some devices. Vertical alignment is done slightly differently for character strings and for expressions: adj = c(0,0) means to left-justify and to align on the baseline for strings but on the bottom of the bounding box for expressions. This also affects vertical centering: for strings the centering excludes any descenders whereas for expressions it includes them. Using NA for strings centers them, including descenders.

The pos and offset arguments can be used in conjunction with values returned by identify to recreate an interactively labelled plot.

Text can be rotated by using graphical parameters srt (see par). When adj is specified, a non-zero srt rotates the label about (x, y). If pos is specified, srt rotates the text about the point on its bounding box which is closest to (x, y): top center for pos = 1, right center for pos = 2, bottom center for pos = 3, and left center for pos = 4. The pos interface is not as useful for rotated text because the result is no longer centered vertically or horizontally with respect to (x, y). At present there is no interface in the graphics package for directly rotating text about its center which is achievable however by fiddling with adj and srt simultaneously.

Graphical parameters col, cex and font can be vectors and will then be applied cyclically to the labels (and extra values will be ignored). NA values of font are replaced by par("font"), and similarly for col.

Labels whose x, y or labels value is NA are omitted from the plot.

What happens when font = 5 (the symbol font) is selected can be both device- and locale-dependent. Most often labels will be interpreted in the Adobe symbol encoding, so e.g."d" is delta, and "\300" is aleph.

References

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

Murrell, P. (2005) R Graphics. Chapman & Hall/CRC Press.

Examples

Run this code

# NOT RUN {
plot(-1:1, -1:1, type = "n", xlab = "Re", ylab = "Im")
K <- 16; text(exp(1i * 2 * pi * (1:K) / K), col = 2)

## The following two examples use latin1 characters: these may not
## appear correctly (or be omitted entirely).
plot(1:10, 1:10, main = "text(...) examples\n~~~~~~~~~~~~~~",
     sub = "R is GNU <U+00A9>, but not <U+00AE> ...")
mtext("<U+00AB>Latin-1 accented chars<U+00BB>: <U+00E9><U+00E8> <U+00F8><U+00D8> <U+00E5><<U+00C5> <U+00E6><<U+00C6>", side = 3)
points(c(6,2), c(2,1), pch = 3, cex = 4, col = "red")
text(6, 2, "the text is CENTERED around (x,y) = (6,2) by default",
     cex = .8)
text(2, 1, "or Left/Bottom - JUSTIFIED at (2,1) by 'adj = c(0,0)'",
     adj = c(0,0))
text(4, 9, expression(hat(beta) == (X^t * X)^{-1} * X^t * y))
text(4, 8.4, "expression(hat(beta) == (X^t * X)^{-1} * X^t * y)",
     cex = .75)
text(4, 7, expression(bar(x) == sum(frac(x[i], n), i==1, n)))

## Two more latin1 examples
text(5, 10.2,
     "Le fran<U+00E7>ais, c'est fa<U+00E7>ile: R<U+00E8>gles, Libert<U+00E9>, Egalit<U+00E9>, Fraternit<U+00E9>...")
text(5, 9.8,
     "Jetz no chli z<U+00FC>rit<U+00FC><U+00FC>tsch: (noch ein bi<U+00DF>chen Z<U+00FC>rcher deutsch)")
# }

Run the code above in your browser using DataLab