Extract.linim.Rd
\name{Extract.linim}
\alias{[.linim}
\title{Extract Subset of Pixel Image on Linear Network}
\description{
Extract a subset of a pixel image on a linear network.
}
\usage{
\method{[}{linim}(x, i, \dots, drop=TRUE)
}
\arguments{
\item{x}{
A pixel image on a linear network (object of class \code{"linim"}).
}
\item{i}{
Spatial window defining the subregion.
Either a spatial window (an object of class \code{"owin"}), or a
logical-valued pixel image,
or any type of index that applies to a matrix,
or a point pattern (an object of class \code{"lpp"} or \code{"ppp"}),
or something that can be converted to a point pattern
by \code{\link{as.lpp}} (using the network on which \code{x} is defined).
}
\item{\dots}{Additional arguments passed to \code{[.im}.}
\item{drop}{Logical value indicating whether \code{NA} values should
be omitted from the result.}
}
\value{
Another pixel image on a linear network (object of class \code{"linim"})
or a vector of pixel values.
}
\details{
This function is a method for the subset operator \code{"["} for
pixel images on linear networks (objects of class \code{"linim"}).
The pixel image \code{x} will be restricted to the
domain specified by \code{i}.
Pixels outside the domain of \code{x} are assigned the value \code{NA};
if \code{drop=TRUE} (the default) such \code{NA} values are deleted
from the result; if \code{drop=FALSE}, then \code{NA} values are retained.
If \code{i} is a window (or a logical-valued pixel image)
then \code{x[i]} is another pixel image of class \code{"linim"},
representing the restriction of \code{x} to the spatial domain
specified by \code{i}.
If \code{i} is a point pattern, then \code{x[i]} is the vector of
pixel values of \code{x} at the locations specified by \code{i}.
}
\examples{
M <- as.mask.psp(as.psp(simplenet))
Z <- as.im(function(x,y){x}, W=M)
Y <- linim(simplenet, Z)
X <- runiflpp(4, simplenet)
Y[X]
Y[square(c(0.3, 0.6))]
}
\author{
\adrian
}
\keyword{spatial}
\keyword{manip}