\HeaderA{prepanel.functions}{Useful Prepanel Function for Lattice}{prepanel.functions}
\aliasA{prepanel.lmline}{prepanel.functions}{prepanel.lmline}
\aliasA{prepanel.loess}{prepanel.functions}{prepanel.loess}
\aliasA{prepanel.qqmathline}{prepanel.functions}{prepanel.qqmathline}
\keyword{dplot}{prepanel.functions}
\begin{Description}\relax
These are predefined prepanel functions available in Lattice.
\end{Description}
\begin{Usage}
\begin{verbatim}
prepanel.lmline(x, y, ...)
prepanel.loess(x, y, span, degree, family, evaluation, ...)
prepanel.qqmathline(x, y = x, distribution = qnorm,
                    p = c(0.25, 0.75), qtype = 7,
                    groups, subscripts,
                    ...) 
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x, y}] x and y values, numeric or factor
\item[\code{distribution}] quantile function for theoretical
distribution. This is automatically passed in when this is used as a
prepanel function in \code{qqmath}.

\item[\code{qtype}] type of \code{\LinkA{quantile}{quantile}}
\item[\code{p}] numeric vector of length two, representing probabilities.  If used
with \code{aspect="xy"}, the aspect ratio will be chosen to make the
line passing through the corresponding quantile pairs as close to 45
degrees as possible.

\item[\code{span, degree, family, evaluation}] arguments controlling the
underlying \code{\LinkA{loess}{loess}} smooth 
\item[\code{groups, subscripts}] See \code{\LinkA{xyplot}{xyplot}}.  Whenever
appropriate, calculations are done separately for each group and
then combined.  
\item[\code{...}] other arguments 
\end{ldescription}
\end{Arguments}
\begin{Value}
usually a list with components \code{xlim}, \code{ylim}, \code{dx} and
\code{dy}, the first two being used to calculate panel axes limits,
the last two for banking computations.  The form of these components
are described under \code{\LinkA{xyplot}{xyplot}}.  There are also several
undocumented prepanel functions that serve as the default for high
level functions, e.g., \code{prepanel.default.xyplot}
\end{Value}
\begin{Author}\relax
Deepayan Sarkar \email{Deepayan.Sarkar@R-project.org}
\end{Author}
\begin{SeeAlso}\relax
\code{\LinkA{trellis.par.get}{trellis.par.get}}, \code{\LinkA{xyplot}{xyplot}},
\code{\LinkA{banking}{banking}}, \code{\LinkA{Lattice}{Lattice}}. See
\code{\LinkA{loess.smooth}{loess.smooth}} for further options to
\code{prepanel.loess}
\end{SeeAlso}

