https://github.com/cran/lattice
Revision 35053e8aa96e7b9e13cdd257a3ea530c82abd8dc authored by Deepayan Sarkar on 06 March 2012, 00:00:00 UTC, committed by Gabor Csardi on 06 March 2012, 00:00:00 UTC
1 parent 53d9745
Tip revision: 35053e8aa96e7b9e13cdd257a3ea530c82abd8dc authored by Deepayan Sarkar on 06 March 2012, 00:00:00 UTC
version 0.20-5
version 0.20-5
Tip revision: 35053e8
level.colors.Rd
\name{D_level.colors}
\alias{level.colors}
\title{
A function to compute false colors representing a numeric or
categorical variable
}
\description{
Calculates false colors from a numeric variable (including factors,
using their numeric codes) given a color scheme and breakpoints.
}
\usage{
level.colors(x, at, col.regions, colors = TRUE, ...)
}
\arguments{
\item{x}{ A numeric or \code{\link{factor}} variable. }
\item{at}{ A numeric variable of breakpoints defining intervals along
the range of \code{x}. }
\item{col.regions}{ A specification of the colors to be assigned to
each interval defined by \code{at}. This could be either a vector
of colors, or a function that produces a vector of colors when
called with a single argument giving the number of colors. See
details below. }
\item{colors}{ logical indicating whether colors should be computed
and returned. If \code{FALSE}, only the indices representing which
interval (among those defined by \code{at}) each value in \code{x}
falls into is returned. }
\item{\dots}{ Extra arguments, ignored. }
}
\value{
A vector of the same length as \code{x}. Depending on the
\code{colors} argument, this could be either a vector of colors (in
a form usable by \R), or a vector of integer indices representing
which interval the values of \code{x} fall in.
}
\author{ Deepayan Sarkar \email{deepayan.sarkar@r-project.org} }
\seealso{ \code{\link{levelplot}}, \code{\link{colorRampPalette}}. }
\details{
If \code{at} has length n, then it defines n-1 intervals. Values of
\code{x} outside the range of \code{at} are not assigned to an
interval, and the return value is \code{NA} for such values.
Colors are chosen by assigning a color to each of the n-1 intervals.
If \code{col.regions} is a palette function (such as
\code{\link{topo.colors}}, or the result of calling
\code{\link{colorRampPalette}}), it is called with n-1 as an argument
to obtain the colors. Otherwise, if there are exactly n-1 colors in
\code{col.regions}, these get assigned to the intervals. If there are
fewer than n-1 colors, \code{col.regions} gets recycled. If there are
more, a more or less equally spaced (along the length of
\code{col.regions}) subset is chosen.
}
\examples{
depth.col <-
with(quakes,
level.colors(depth, at = do.breaks(range(depth), 30),
col.regions = terrain.colors))
xyplot(lat ~ long | equal.count(stations), quakes,
strip = strip.custom(var.name = "Stations"),
colours = depth.col,
panel = function(x, y, colours, subscripts, ...) {
panel.xyplot(x, y, pch = 21, col = "transparent",
fill = colours[subscripts], ...)
})
}
\keyword{utilities}
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