https://github.com/cran/spatstat
Tip revision: 7c29845cd80606f8ceb6cc1904f98fc86bf77b7e authored by Adrian Baddeley on 05 February 2008, 04:20:32 UTC
version 1.12-6
version 1.12-6
Tip revision: 7c29845
crossdist.ppp.Rd
\name{crossdist.ppp}
\alias{crossdist.ppp}
\title{Pairwise distances between two different point patterns}
\description{
Computes the distances between pairs of points
taken from two different point patterns.
}
\usage{
\method{crossdist}{ppp}(X, Y, \dots, periodic=FALSE, method="C")
}
\arguments{
\item{X,Y}{
Point patterns (objects of class \code{"ppp"}).
}
\item{\dots}{
Ignored.
}
\item{periodic}{
Logical. Specifies whether to apply a periodic edge correction.
}
\item{method}{String specifying which method of calculation to use.
Values are \code{"C"} and \code{"interpreted"}.
}
}
\value{
A matrix whose \code{[i,j]} entry is the distance
from the \code{i}-th point in \code{X}
to the \code{j}-th point in \code{Y}.
}
\details{
Given two point patterns,
this function computes the Euclidean distance from each point
in the first pattern to each point in the second pattern,
and returns a matrix containing these distances.
This is a method for the generic function \code{\link{crossdist}}
for point patterns (objects of class \code{"ppp"}).
This function expects two
point patterns \code{X} and \code{Y}, and returns the matrix
whose \code{[i,j]} entry is the distance from \code{X[i]} to
\code{Y[j]}.
Alternatively if \code{periodic=TRUE}, then provided the windows
containing \code{X} and \code{Y} are identical and are rectangular,
then the distances will be computed in the `periodic'
sense (also known as `torus' distance): opposite edges of the
rectangle are regarded as equivalent.
This is meaningless if the window is not a rectangle.
The argument \code{method} is not normally used. It is
retained only for checking the validity of the software.
If \code{method = "interpreted"} then the distances are
computed using interpreted R code only. If \code{method="C"}
(the default) then C code is used.
The C code is faster by a factor of 4.
}
\seealso{
\code{\link{crossdist}},
\code{\link{crossdist.default}},
\code{\link{crossdist.psp}},
\code{\link{pairdist}},
\code{\link{nndist}},
\code{\link{Gest}}
}
\examples{
data(cells)
d <- crossdist(cells, runifpoint(6))
d <- crossdist(cells, runifpoint(6), periodic=TRUE)
}
\author{Pavel Grabarnik
\email{pavel.grabar@issp.serpukhov.su}
and
Adrian Baddeley
\email{adrian@maths.uwa.edu.au}
\url{http://www.maths.uwa.edu.au/~adrian/}
}
\keyword{spatial}
\keyword{math}