R: Pairwise distances in Three Dimensions

pairdist.pp3 {spatstat} | R Documentation

## 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 Baddeley Adrian.Baddeley@curtin.edu.au

based on two-dimensional code by Pavel Grabarnik.

### See Also

`pairdist`, `crossdist`, `nndist`, `K3est`

### Examples

       X <- runifpoint3(20)
       d <- pairdist(X)
       d <- pairdist(X, periodic=TRUE)
       d <- pairdist(X, squared=TRUE)

[Package spatstat version 1.54-0 Index]