pairdist {spatstat}R Documentation

Pairwise distances

Description

Computes the matrix of distances between all pairs of points in a point pattern.

Usage

  pairdist(X, ..., method="C")
  pairdist.ppp(X, ..., method="C")
  pairdist.default(X, Y=NULL, ..., method="C")

Arguments

X,Y Arguments specifying the locations of a set of points. For pairdist.ppp, the argument X should be a point pattern (object of class "ppp"). For pairdist.default, typically X and Y would be numeric vectors of equal length. Alternatively Y may be omitted and X may be a list with two components x and y, or a matrix with two columns.
... Ignored by pairdist.ppp and pairdist.default.
method String specifying which method of calculation to use. Values are "C" and "interpreted". Usually not specified.

Details

This function computes the Euclidean distances between all pairs of points, and returns the matrix of distances.

The function pairdist is generic, with a method for point patterns (objects of class "ppp") and a default method.

The method for point patterns expects a single point pattern argument X and returns the matrix of its pairwise distances.

The default method expects that X and Y will determine the coordinates of a set of points. Typically X and Y would be numeric vectors of equal length. Alternatively Y may be omitted and X may be a list with two components named x and y, or a matrix or data frame with two columns.

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 somewhat faster.

Value

A square matrix whose [i,j] entry is the distance between the points numbered i and j.

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, nndist, Kest

Examples

   data(cells)
   d <- pairdist(cells)

   x <- runif(100)
   y <- runif(100)
   d <- pairdist(x, y)

[Package spatstat version 1.6-8 Index]