superimpose.Rd
\name{superimpose}
\alias{superimpose}
\title{Superimpose Several Point Patterns}
\description{
Superimpose any number of point patterns.
}
\usage{
superimpose(\dots, W=NULL, check=TRUE)
}
\arguments{
\item{\dots}{
Any number of arguments, each of which represents a point pattern.
Each argument must be either a point pattern
object (of class \code{"ppp"}) or a structure
containing elements \code{x} and \code{y}.
}
\item{W}{
Optional. Window for the resulting point pattern.
An object of class \code{"owin"}, or something
acceptable to \code{\link{as.owin}}.
}
\item{check}{
Logical value (passed to \code{\link{ppp}})
determining whether to check the geometrical validity of the
resulting point pattern.
}
}
\value{
A point pattern (object of class \code{"ppp"}) representing the
superposition (union) of all the point patterns.
}
\details{
This function is used to superimpose two or more point patterns
(see also \code{\link{concatxy}}).
Each of the arguments in
\code{\dots} is either a point pattern object (of class \code{"ppp"})
or a structure containing (at least) the elements
\code{x} and \code{y}. The point patterns are not required to have
the same window of observation.
The window for the superimposed point pattern is
specified by \code{W}. Its default value is
the union of the windows of all the point patterns.
If any of the arguments is a \emph{marked} point pattern,
then all of them must be.
In that case, the result is also a marked point pattern.
If the arguments are given in the form \code{name=value},
then the names will be used
as marks attached to the corresponding points. See the last line
in the Examples.
}
\seealso{
\code{\link{concatxy}},
\code{\link{quadscheme}}.
See \code{\link{superimposePSP}} for superimposing patterns of line segments.
}
\examples{
dat <- runifrect(30)
xy <- list(x=runif(10),y=runif(10))
new <- superimpose(dat, xy)
\dontrun{plot(new)}
# how to make a 2-type point pattern with types "a" and "b"
u <- superimpose(a = rpoispp(10), b = rpoispp(20))
# how to make a 2-type point pattern with types 1 and 2
u <- superimpose("1" = rpoispp(10), "2" = rpoispp(20))
}
\author{Adrian Baddeley
\email{adrian@maths.uwa.edu.au}
\url{http://www.maths.uwa.edu.au/~adrian/}
and Rolf Turner
\email{r.turner@auckland.ac.nz}
}
\keyword{spatial}
\keyword{manip}