https://github.com/cran/spatstat
Tip revision: 23d61251adb9bd109605170b55856851ca066bbc authored by Adrian Baddeley on 08 May 2017, 13:31:46 UTC
version 1.51-0
version 1.51-0
Tip revision: 23d6125
raster.x.Rd
\name{raster.x}
\alias{raster.x}
\alias{raster.y}
\alias{raster.xy}
\title{Cartesian Coordinates for a Pixel Raster}
\description{
Return the \eqn{x} and \eqn{y} coordinates
of each pixel in a pixel image or binary mask.
}
\usage{
raster.x(w, drop=FALSE)
raster.y(w, drop=FALSE)
raster.xy(w, drop=FALSE)
}
\arguments{
\item{w}{
A pixel image (object of class \code{"im"}) or a
mask window (object of class \code{"owin"}
of type \code{"mask"}).
}
\item{drop}{
Logical.
If \code{TRUE}, then coordinates of pixels that lie outside the
window are removed.
If \code{FALSE} (the default) then the coordinates of every
pixel in the containing rectangle are retained.
}
}
\value{
\code{raster.xy} returns a list with components \code{x} and \code{y}
which are numeric vectors of equal length containing the pixel coordinates.
If \code{drop=FALSE},
\code{raster.x} and \code{raster.y} return
a matrix of the same dimensions as the pixel grid in \code{w},
and giving the value of the \eqn{x} (or \eqn{y}) coordinate
of each pixel in the raster.
If \code{drop=TRUE},
\code{raster.x} and \code{raster.y} return numeric vectors.
}
\details{
The argument \code{w} should be either
a pixel image (object of class \code{"im"})
or a mask window (an object of class
\code{"owin"} of type \code{"mask"}).
If \code{drop=FALSE} (the default), the
functions \code{raster.x} and \code{raster.y} return
a matrix of the same dimensions as the
pixel image or mask itself, with entries giving the \eqn{x} coordinate
(for \code{raster.x}) or \eqn{y} coordinate (for \code{raster.y})
of each pixel in the pixel grid.
If \code{drop=TRUE}, pixels that lie outside the
window \code{w} (or outside the domain of the image \code{w})
are removed, and \code{raster.x} and \code{raster.y}
return numeric vectors containing the coordinates of the
pixels that are inside the window \code{w}.
The function \code{raster.xy} returns a list
with components \code{x} and \code{y}
which are numeric vectors of equal length containing the pixel coordinates.
}
\seealso{
\code{\link{owin}},
\code{\link{as.mask}},
\code{\link{pixelcentres}}
}
\examples{
u <- owin(c(-1,1),c(-1,1)) # square of side 2
w <- as.mask(u, eps=0.01) # 200 x 200 grid
X <- raster.x(w)
Y <- raster.y(w)
disc <- owin(c(-1,1), c(-1,1), mask=(X^2 + Y^2 <= 1))
\dontrun{plot(disc)}
# approximation to the unit disc
}
\author{\adrian
,
\rolf
and \ege
}
\keyword{spatial}
\keyword{manip}