https://github.com/cran/spatstat
Tip revision: 198d8db539783cb2d4f1347b81b82519926116b2 authored by Adrian Baddeley on 01 April 2009, 11:43:18 UTC
version 1.15-1
version 1.15-1
Tip revision: 198d8db
crossdist.default.Rd
\name{crossdist.default}
\alias{crossdist.default}
\title{Pairwise distances between two different sets of points}
\description{
Computes the distances between each pair of points
taken from two different sets of points.
}
\usage{
\method{crossdist}{default}(X, Y, x2, y2, \dots, period=NULL, method="C")
}
\arguments{
\item{X,Y}{
Numeric vectors of equal length specifying the coordinates of
the first set of points.
}
\item{x2,y2}{
Numeric vectors of equal length specifying the coordinates of
the second set of points.
}
\item{\dots}{
Ignored.
}
\item{period}{
Optional. Dimensions for 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 the first set of points
to the \code{j}-th point in the second set of points.
}
\details{
Given two sets of points,
this function computes the Euclidean distance from each point
in the first set to each point in the second set,
and returns a matrix containing these distances.
This is a method for the generic function \code{\link{crossdist}}.
This function expects \code{X} and \code{Y} to be numeric vectors
of equal length specifying the coordinates of the first set of points.
The arguments \code{x2},\code{y2} specify the coordinates of the
second set of points.
Alternatively if \code{period} is given,
then the distances will be computed in the `periodic'
sense (also known as `torus' distance).
The points will be treated as if they are in a rectangle
of width \code{period[1]} and height \code{period[2]}.
Opposite edges of the rectangle are regarded as equivalent.
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.ppp}},
\code{\link{crossdist.psp}},
\code{\link{pairdist}},
\code{\link{nndist}},
\code{\link{Gest}}
}
\examples{
d <- crossdist(runif(7), runif(7), runif(12), runif(12))
d <- crossdist(runif(7), runif(7), runif(12), runif(12), period=c(1,1))
}
\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}