\HeaderA{panel.superpose}{Panel Function for Display Marked by groups}{panel.superpose}
\methaliasA{panel.superpose.2}{panel.superpose}{panel.superpose.2}
\keyword{dplot}{panel.superpose}
\begin{Description}\relax
These are panel functions for Trellis displays useful when a grouping
variable is specified for use within panels. The \code{x} (and
\code{y} where appropriate) variables are plotted with different
graphical parameters for each distinct value of the grouping variable.
\end{Description}
\begin{Usage}
\begin{verbatim}
panel.superpose(x, y, panel.groups = "panel.xyplot",
                subscripts, groups, type="p", ...)
panel.superpose.2(x, y, panel.groups = "panel.xyplot",
                  subscripts, groups, type="p", ...)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x,y}] coordinates of the points to be displayed
\item[\code{panel.groups}] the panel function to be used for each group of points. Defaults to
\code{panel.xyplot} (behaviour in S)

\item[\code{subscripts}] subscripts giving indices in original data frame 
\item[\code{groups}] a grouping variable. Different graphical parameters
will be used to plot the subsets of observations given by each
distinct value of \code{groups}. The default graphical parameters
are obtained from \code{superpose.symbol} and \code{superpose.line}
using \code{\LinkA{trellis.par.get}{trellis.par.get}} wherever appropriate

\item[\code{type}] usually a character vector specifying what should be drawn for each
group, passed on to the \code{panel.groups} function, which must
know what to do with it.  By default, this is
\code{\LinkA{panel.xyplot}{panel.xyplot}}, whose help page describes the admissible
values.

The two functions \code{panel.superpose} and
\code{panel.superpose.2} differ only in the way the \code{type}
argument is interpreted.  For the former, the interpretation is the
same as for \code{panel.xyplot} for each of the unique groups.  In
other words, if \code{type} is a vector, all the individual
components are honoured concurrently.  For the latter, \code{type}
is replicated to be as long as the number of unique values in
\code{groups}, and one component used for the points corresponding
to the each different group.  Even in this case, it is possible to
request multiple types per group, specifying \code{type} as a list,
each component being the desired \code{type} vector for the
corresponding plot.

\item[\code{...}] other arguments (mostly graphical parameters, replicated
to be as long as the number of groups), ultimately passed down to
\code{panel.xyplot}. In particular, colour can be specified using 3
arguments (\code{col}, \code{col.line} and \code{col.symbol}), as
described in \code{\LinkA{panel.xyplot}{panel.xyplot}}.

\end{ldescription}
\end{Arguments}
\begin{Author}\relax
Deepayan Sarkar \email{Deepayan.Sarkar@R-project.org}
(\code{panel.superpose.2} originally contributed by Neil Klepeis)
\end{Author}
\begin{SeeAlso}\relax
Different functions when used as \code{panel.groups} gives different
types of plots, for example \code{\LinkA{panel.xyplot}{panel.xyplot}},
\code{\LinkA{panel.dotplot}{panel.dotplot}} and \code{\LinkA{panel.linejoin}{panel.linejoin}} (This can
be used to produce interaction plots).
\end{SeeAlso}

