Pairwise distances between two different point patterns

Description

Computes the distances between pairs of points taken from two different point patterns.

Usage

  ## S3 method for class 'ppp':
  crossdist(X, Y, ..., periodic=FALSE, method="C")

Arguments

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 crossdist for point patterns (objects of class "ppp").

This function expects two point patterns X and Y, and returns the matrix whose [i,j] entry is the distance from X[i] to Y[j].

Alternatively if periodic=TRUE, then provided the windows containing X and 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 method is not normally used. It is retained only for checking the validity of the software. If method = "interpreted" then the distances are computed using interpreted R code only. If method="C" (the default) then C code is used. The C code is faster by a factor of 4.

Value

A matrix whose [i,j] entry is the distance from the i-th point in X to the j-th point in Y.

Author(s)

Pavel Grabarnik pavel.grabar@issp.serpukhov.su and Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/

See Also

crossdist, crossdist.default, crossdist.psp, pairdist, nndist, Gest

Examples

   data(cells)
   d <- crossdist(cells, runifpoint(6))
   d <- crossdist(cells, runifpoint(6), periodic=TRUE)