\name{G_banking}
\alias{banking}
\title{Banking}
\description{
Calculates banking slope
}
\usage{
banking(dx, dy)
}
\arguments{
\item{dx, dy}{ vector of consecutive x, y differences. }
}
\details{
\code{banking} is the banking function used when
\code{aspect = "xy"} in high level Trellis functions. It is usually not
very meaningful except with \code{xyplot}. It considers the
absolute slopes (based on \code{dx} and \code{dy}) and returns a value
which when adjusted by the panel scale limits will make the median of
the above absolute slopes correspond to a 45 degree line.
This function was inspired by the discussion of banking in the
documentation for Trellis Graphics available at Bell Labs' website
(see \code{\link{Lattice}}), but is most likely identical to an
algorithm described by Cleveland et al (see below). It is
not clear (to the author) whether this is the algorithm used in
S-PLUS. Alternative banking rules, implemented as a similar function,
can be used as a drop-in replacement by suitably modifying
\code{lattice.options("banking")}.
}
\examples{
xyplot(sunspot.year ~ time(sunspot.year) | equal.count(time(sunspot.year)),
xlab = "", type = "l", aspect = "xy", strip = FALSE,
scales = list(x = list(alternating = 2, relation = "sliced")),
as.table = TRUE, main = "Yearly Sunspots")
}
\references{
Cleveland, William S., McGill, Marylyn E. and McGill, Robert (1988),
"The Shape Parameter of a Two-variable Graph",
\emph{Journal of the American Statistical Association}, 83, 289-300
}
\author{ Deepayan Sarkar \email{Deepayan.Sarkar@R-project.org}}
\seealso{\code{\link{Lattice}}, \code{\link{xyplot}}}
\keyword{dplot}