\name{Dotplot}
\alias{Dotplot}

\title{
Dot Plots
}
\description{
Dot plot of numeric variable, either using raw values or binned, 
optionally classified by a factor. Dot plots are useful for visualizing the
distribution of a numeric variable in a small data set.}

\usage{
Dotplot(x, by, bin = FALSE, breaks, xlim, 
    xlab = deparse(substitute(x)))
}

\arguments{
  \item{x}{a numeric variable.}
  \item{by}{optionally a factor (or character or logical variable) by which to classify \code{x}.}
  \item{bin}{if \code{TRUE} (the default is \code{FALSE}), the values of \code{x} are binned, 
    as in a histogram, prior to plotting.}
  \item{breaks}{breaks for the bins, in a form acceptable to the \code{\link{hist}} function;
    the default is \code{"Sturges"}.}
  \item{xlim}{optional 2-element numeric vector giving limits of the horizontal axis.}
  \item{xlab}{optional character string to label horizontal axis.}
}

\details{
If the \code{by} argument is specified, then one dot plot is produced for each
level of \code{by}; these are arranged vertically and all use the same scale
for \code{x}. An attempt is made to adjust the size of the dots to the space
available without making them too big.
}

\value{
Returns \code{NULL} invisibly.
}

\author{
John Fox \email{jfox@mcmaster.ca}
}

\seealso{
\code{\link{hist}}
}

\examples{
if (require(car)){
  data(Duncan)
  with(Duncan, {
    Dotplot(education)
    Dotplot(education, bin=TRUE)
    Dotplot(education, by=type)
    Dotplot(education, by=type, bin=TRUE)
  })
}
}

\keyword{hplot}
