# 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)
# }
```

*Documentation reproduced from package spatstat, version 1.55-1, License: GPL (>= 2)*