\Header{text}{Add Text to a Plot}
\methalias{text.default}{text}
\keyword{aplot}{text}
\begin{Description}\relax
\code{text} draws the strings given in the vector \code{labels} at the
coordinates given by \code{x} and \code{y}.
\code{y} may be missing since \code{\Link{xy.coords}(x,y)} is used for
construction of the coordinates.
\end{Description}
\begin{Usage}
\begin{verbatim}
text(x, ...)

## Default S3 method:
text (x, y = NULL, labels = seq(along = x), adj = NULL,
     pos = NULL, offset = 0.5, vfont = NULL,
     cex = 1, col = NULL, font = NULL, xpd = NULL, ...)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x, y}] numeric vectors of coordinates where the text
\code{labels} should be written.  If the length of \code{x} and
\code{y} differs, the shorter one is recycled.
\item[\code{labels}] one or more character strings or expressions specifying
the \emph{text} to be written.  An attempt is made
to coerce other vectors to character, and other language objects
to expressions.
\item[\code{adj}] one or two values in \eqn{[0,1]}{} which specify the x
(and optionally y) adjustment of the labels.  On most devices values
outside that interval will also work.
\item[\code{pos}] a position specifier for the text.  If specified this
overrides any \code{adj} value given.  Values of \code{1},
\code{2}, \code{3} and \code{4}, respectively indicate
positions below, to the left of, above and to the right of
the specified coordinates.
\item[\code{offset}] when \code{pos} is specified, this value gives the
offset of the label from the specified coordinate in fractions
of a character width.
\item[\code{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.
\item[\code{cex}] numeric \bold{c}haracter \bold{ex}pansion factor; multiplied
by \code{\Link{par}("cex")} yields the final character size.
\item[\code{col, font}] the color and font to be used; these default to the
values of the global graphical parameters in \code{\Link{par}()}.
\item[\code{xpd}] (where) should clipping take place?  Defaults to
\code{\Link{par}("xpd")}.
\item[\code{...}] further graphical parameters (from \code{\Link{par}}).
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
\code{labels} must be of type \code{\Link{character}} or
\code{\Link{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.

\code{adj} allows \emph{adj}ustment of the text with respect to \code{(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.,
\code{adj = c(0.5, 0.5)}. Accurate vertical centering needs
character metric information on individual characters, which is
only available on some devices.

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

Text can be rotated by using graphical parameters \code{srt} (see
\code{\Link{par}}); this rotates about the centre set by \code{adj}.

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

Labels whose \code{x}, \code{y}, \code{labels}, \code{cex} or \code{col}
value is \code{NA} are omitted from the plot.
\end{Details}
\begin{References}\relax
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
\emph{The New S Language}.
Wadsworth \& Brooks/Cole.
\end{References}
\begin{SeeAlso}\relax
\code{\Link{mtext}}, \code{\Link{title}},
\code{\Link{Hershey}} for details on Hershey vector fonts,
\code{\Link{plotmath}} for details and more examples on
mathematical annotation.
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
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 ©, but not ® ...")
mtext("«ISO-accents»: ± éè øØ å<Å æ<Æ", 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 français, c'est façile: Règles, Liberté, Egalité, Fraternité...")
text(5,9.8, "Jetz no chli züritüütsch: (noch ein bißchen Zürcher deutsch)")
\end{ExampleCode}
\end{Examples}

