project2set.Rd
\name{project2set}
\alias{project2set}
\title{
Find Nearest Point in a Region
}
\description{
For each data point in a point pattern \code{X},
find the nearest location in a given spatial region \code{W}.
}
\usage{
project2set(X, W, \dots)
}
\arguments{
\item{X}{
Point pattern (object of class \code{"ppp"}).
}
\item{W}{
Window (object of class \code{"owin"})
or something acceptable to \code{\link{as.owin}}.
}
\item{\dots}{
Arguments passed to \code{\link{as.mask}} controlling the
pixel resolution.
}
}
\details{
The window \code{W} is first discretised as a binary mask
using \code{\link{as.mask}}.
For each data point \code{X[i]} in the point pattern \code{X},
the algorithm finds the nearest pixel in \code{W}.
The result is a point pattern \code{Y} containing these nearest points,
that is, \code{Y[i]} is the nearest point in \code{W} to the
point \code{X[i]}.
}
\value{
A point pattern (object of class \code{"ppp"}) with the same
number of points as \code{X} in the window \code{W}.
}
\author{\adrian
\rolf
and \ege
}
\seealso{
\code{\link{project2segment}},
\code{\link{nncross}}
}
\examples{
He <- heather$fine[owin(c(2.8, 7.4), c(4.0, 7.8))]
plot(He, main="project2set")
X <- runifpoint(4, erosion(complement.owin(He), 0.2))
points(X, col="red")
Y <- project2set(X, He)
points(Y, col="green")
arrows(X$x, X$y, Y$x, Y$y, angle=15, length=0.2)
}
\keyword{spatial}
\keyword{math}