pairdist.pp3: Pairwise distances in Three Dimensions

In spatstat.geom: Geometrical Functionality of the 'spatstat' Family

Pairwise distances in Three Dimensions

Description

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

Usage

  ## S3 method for class 'pp3'
pairdist(X, ..., periodic=FALSE, squared=FALSE)

Arguments

X	A point pattern (object of class "pp3").
...	Ignored.
periodic	Logical. Specifies whether to apply a periodic edge correction.
squared	Logical. If squared=TRUE, the squared distances are returned instead (this computation is faster).

Details

This is a method for the generic function pairdist.

Given a three-dimensional point pattern X (an object of class "pp3"), this function computes the Euclidean distances between all pairs of points in X, and returns the matrix of distances.

Alternatively if periodic=TRUE and the window containing X is a box, then the distances will be computed in the ‘periodic’ sense (also known as ‘torus’ distance): opposite faces of the box are regarded as equivalent. This is meaningless if the window is not a box.

If squared=TRUE then the squared Euclidean distances d^2 are returned, instead of the Euclidean distances d. The squared distances are faster to calculate, and are sufficient for many purposes (such as finding the nearest neighbour of a point).

Value

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

Author(s)

\adrian

based on two-dimensional code by \pavel.

See Also

pairdist, crossdist, nndist, K3est

Examples

if(require(spatstat.random)) {
   X <- runifpoint3(20)
} else {
   X <- osteo$pts[[1]]
}
   d <- pairdist(X)
   d <- pairdist(X, periodic=TRUE)
   d <- pairdist(X, squared=TRUE)

spatstat.geom documentation built on Sept. 18, 2024, 9:08 a.m.