points.lpp.Rd
\name{points.lpp}
\alias{points.lpp}
\title{
Draw Points on Existing Plot
}
\description{
For a point pattern on a linear network, this function draws the
coordinates of the points only, on the existing plot display.
}
\usage{
\method{points}{lpp}(x, \dots)
}
\arguments{
\item{x}{
A point pattern on a linear network (object of class \code{"lpp"}).
}
\item{\dots}{
Additional arguments passed to \code{\link[graphics]{points.default}}.
}
}
\details{
This is a method for the generic function
\code{\link[graphics]{points}}
for the class \code{"lpp"} of point patterns on a linear network.
If \code{x} is a point pattern on a linear network, then
\code{points(x)} plots the spatial coordinates of the points only,
on the existing plot display,
without plotting the underlying network.
It is an error to call this function if a plot has not yet been
initialised.
The spatial coordinates are extracted and passed to
\code{\link[graphics]{points.default}} along with any extra arguments.
Arguments controlling the colours and the plot symbols are interpreted
by \code{\link[graphics]{points.default}}. For example, if the
argument \code{col} is a vector, then the \code{i}th point is drawn
in the colour \code{col[i]}.
}
\section{Difference from plot method}{
The more usual way to plot the points is using \code{\link{plot.lpp}}.
For example \code{plot(x)} would plot both the points and the
underlying network, while \code{plot(x, add=TRUE)} would plot only the
points. The interpretation of arguments controlling the colours and
plot symbols is different here: they determine a symbol map, as explained
in the help for \code{\link{plot.ppp}}.
}
\value{
Null.
}
\author{
\spatstatAuthors.
}
\seealso{
\code{\link{plot.lpp}}, \code{\link[graphics]{points.default}}
}
\examples{
plot(Frame(spiders), main="Spiders on a Brick Wall")
points(spiders)
}
\keyword{spatial}
\keyword{hplot}