spatstat.geom (version 3.2-8)

pairdist.pp3: 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 pp3
pairdist(X, ..., periodic=FALSE, squared=FALSE)

Value

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

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).

Author

Adrian Baddeley based on two-dimensional code by Pavel Grabarnik .

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).

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)