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\name{D_simpleKey}
\alias{simpleKey}
\title{ Function to generate a simple key }
\description{
Simple interface to generate a list appropriate for \code{draw.key}
}
\usage{
simpleKey(text, points = TRUE,
rectangles = FALSE,
lines = FALSE,
col, cex, alpha, font,
fontface, fontfamily,
lineheight, \dots)
}
\arguments{
\item{text}{
character or expression vector, to be used as labels for levels of
the grouping variable
}
\item{points}{ logical }
\item{rectangles}{ logical }
\item{lines}{ logical }
\item{col, cex, alpha, font, fontface, fontfamily, lineheight}{
Used as top-level components of the list produced, to be used for
the text labels. Defaults to the values in
\code{trellis.par.get("add.text")}
}
\item{\dots}{
further arguments added to the list, eventually passed to
\code{draw.key}
}
}
\details{
A lattice plot can include a legend (key) if an appropriate list is
specified as the \code{key} argument to a high level Lattice function
such as \code{xyplot}. This key can be very flexible, but that
flexibility comes at a cost: this list needs to be fairly complicated
even in simple situations. \code{simpleKey} is designed as a useful
shortcut in the common case of a key drawn in conjunction with a
grouping variable, using the default graphical settings.
The \code{simpleKey} function produces a suitable \code{key} argument
using a simpler interface. The resulting list will use the
\code{text} argument as a text component, along with at most one set
each of points, rectangles, and lines. The number of entries (rows)
in the key will be the length of the \code{text} component. The
graphical parameters for the additional components will be derived
from the default graphical settings (wherein lies the simplification,
as otherwise these would have to be provided explicitly).
Calling \code{simpleKey} directly is usually unnecessary. It is most
commonly invoked (during the plotting of the \code{"trellis"} object)
when the \code{auto.key} argument is supplied in a high-level plot
with a \code{groups} argument. In that case, the \code{text} argument
of \code{simpleKey} defaults to \code{levels(groups)}, and the
defaults for the other arguments depend on the relevant high-level
function. Note that these defaults can be overridden by supplying
\code{auto.key} as a list containing the replacement values.
}
\value{
A list that would work as the \code{key} argument to
\code{\link{xyplot}}, etc.
}
\author{ Deepayan Sarkar \email{Deepayan.Sarkar@R-project.org}}
\seealso{
\code{\link{Lattice}}, \code{\link{draw.key}},
\code{\link{trellis.par.get}}, and
\code{\link{xyplot}}, specifically the entry for \code{auto.key}.
}
\keyword{dplot}
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