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\name{arctext}
\title{Display text on a circular arc}
\description{Displays a character string on the circumference of an imaginary
circle on an existing plot.}
\usage{
arctext(x,center=c(0,0),radius=1,start=NULL,middle=pi/2,end=NULL,stretch=1,
clockwise=TRUE,cex=NULL,...)
}
\alias{arctext}
\arguments{
\item{x}{A character string.}
\item{center}{The center of the circular arc in x/y user units.}
\item{radius}{The radius of the arc in user units.}
\item{start}{The starting position of the string in radians.}
\item{middle}{The middle position of the string in radians.}
\item{end}{The end position of the string in radians.}
\item{stretch}{How much to stretch the string for appearance.}
\item{clockwise}{Whether to print the string in the clockwise direction.}
\item{cex}{The character expansion factor.}
\item{...}{additional arguments passed to \samp{text}.}
}
\details{
\samp{arctext} displays a string along a circular arc, rotating each
letter. This may not work on all devices, as not all graphic devices
can rotate text to arbitrary angles. The output looks best on a
Postscript or similar device that can rotate text without distortion.
Rotated text often looks very ragged on small bitmaps.
If the user passes a value for
\samp{start}, this will override any value passed to \samp{middle}.
If the plot area is not square, see \samp{par(pty="s")}, the arc will
be somewhat elliptical.
If the \samp{clockwise} argument is TRUE, the string will be displayed
in a clockwise direction and the orientation of the characters will be
rotated \samp{pi} radians (180 degrees). This is useful when the string
is to be displayed on the bottom of the circumference.
}
\value{nil}
\author{Jim Lemon - Thanks to Suhas Parandekar for the idea, Ted Toal
for greatly improving the placement of the text and Andy South for
providing the initial code for the clockwise argument.}
\seealso{\link{text}}
\examples{
plot(0, xlim = c(1, 5),ylim = c(1, 5),main = "Test of arctext", xlab = "",
ylab = "", type = "n")
arctext("bendy like spaghetti", center = c(3,3), col = "blue")
arctext("bendy like spaghetti", center = c(3,3), radius = 1.5, start = pi,
cex = 2)
arctext("bendy like spaghetti", center = c(3, 3),radius = 0.5,
start = pi/2, stretch = 1.2)
arctext("bendy like spaghetti", center = c(3, 3), radius = 1.7,
start = 4 * pi / 3, cex = 1.3, clockwise = FALSE)
}
\keyword{misc}
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