pairdist.pp3
Pairwise distances in Three Dimensions
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)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
Examples
# NOT RUN {
X <- runifpoint3(20)
d <- pairdist(X)
d <- pairdist(X, periodic=TRUE)
d <- pairdist(X, squared=TRUE)
# }