connected.ppp.Rd
\name{connected.ppp}
\Rdversion{1.1}
\alias{connected.ppp}
\title{
Connected Components of a Point Pattern
}
\description{
Finds the topologically-connected components of a point pattern,
when all pairs of points closer than a threshold distance are joined.
}
\usage{
\method{connected}{ppp}(X, R, \dots)
}
\arguments{
\item{X}{
A point pattern (object of class \code{"ppp"}).
}
\item{R}{
Threshold distance. Pairs of points closer than \code{R} units apart
will be joined together.
}
\item{\dots}{
Other arguments, not recognised by these methods.
}
}
\details{
This function can be used to identify clumps of points in a point pattern.
The function \code{connected} is generic. This is the method for
point patterns (objects of class \code{"ppp"}).
The point pattern \code{X} is first converted into an abstract graph
by joining every pair of points that lie closer than \code{R} units
apart. Then the connected components of this graph are identified.
Two points in \code{X} belong to the same connected component if they
can be reached by a series of steps between points of \code{X},
each step being shorter than \code{R} units in length.
The result is a vector of labels for the points of \code{X}
where all the points in a connected component have the same label.
}
\value{
A point pattern, equivalent to \code{X} except that the points
have factor-valued marks, with levels corresponding to the
connected components.
}
\seealso{
\code{\link{connected.im}},
\code{\link{im.object}},
\code{\link{tess}}
}
\examples{
Y <- connected(redwoodfull, 0.1)
if(interactive()) {
plot(Y, cols=1:length(levels(marks(Y))),
main="connected(redwoodfull, 0.1)")
}
}
\author{
\adrian
and \rolf
}
\keyword{spatial}
\keyword{math}