# pairdist.pp3

0th

Percentile

##### Pairwise distances in Three Dimensions

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

Keywords
spatial, math
##### Usage
## S3 method for class 'pp3':
pairdist(X, \dots, 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.

##### See Also

pairdist, crossdist, nndist, K3est

• pairdist.pp3
##### Examples
X <- runifpoint3(20)
d <- pairdist(X)
d <- pairdist(X, periodic=TRUE)
d <- pairdist(X, squared=TRUE)
Documentation reproduced from package spatstat, version 1.20-2, License: GPL (>= 2)

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