R: Add Text to a Plot

text {base}

R Documentation

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, ...)
text.default (x, y = NULL, labels = seq(along = x), adj = NULL,
       pos = NULL, offset = 0.5, vfont = NULL,
       cex = 1, col = NULL, font = NULL, xpd = 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`	one or more character strings or expressions specifying the text to be written.
`adj`	one or two values in `[0,1]` which specify the x (and optionally y) adjustment of the labels. On most devices values outside that interval will also work.
`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 coordinates.
`offset`	when `pos` is specified, this value gives the offset of the label from the specified coordinate in fractions of a character width.
`vfont`	if a character vector of length 2 is specified, then Hershey vector fonts are used. The first element of the vector selects a typeface and the second element selects a style.
`cex`	numeric character expansion factor; multiplied by `par("cex")` yields the final character size.
`col`, `font`	the color and font to be used; these default to the values of the global graphical parameters in `par()`.
`xpd`	(where) should clipping take place? Defaults to `par("xpd")`.
`...`	further graphical parameters (from `par`).

Details

labels must be of type character or expression. 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 with respect to (x,y). Values of 0, 0.5, and 1 specify left/bottom, middle and right/top, respectively. The default is for centered text, i.e., adj = c(0.5, 0.5). Accurate vertical centering needs character metric information on individual characters, which is only available on some devices.

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); this rotates about the centre set by adj.

Graphical parameters col, cex and font can be vectors and will then be applied cyclically to the labels (and extra values will be ignored).

Examples

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 <a9>, but not <ae> ...")
mtext("<ab>ISO-accents<bb>: <b1> <e9><e8> <f8><d8> <e5><<c5> <e6><<c6>", 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<e7>ais, c'est fa<e7>ile: R<e8>gles, Libert<e9>, Egalit<e9>, Fraternit<e9>...")
text(5,9.8, "Jetz no chli z<fc>rit<fc><fc>tsch: (noch ein bi<df>chen Z<fc>rcher deutsch)")