# crossdist.ppp

##### Pairwise distances between two different point patterns

Computes the distances between pairs of points taken from two different point patterns.

##### Usage

```
## S3 method for class 'ppp':
crossdist(X, Y, \dots, periodic=FALSE, method="C")
```

##### Arguments

- X,Y
- Point patterns (objects of class
`"ppp"`

). - ...
- Ignored.
- periodic
- Logical. Specifies whether to apply a periodic edge correction.
- method
- String specifying which method of calculation to use.
Values are
`"C"`

and`"interpreted"`

.

##### Details

Given two point patterns, this function computes the Euclidean distance from each point in the first pattern to each point in the second pattern, and returns a matrix containing these distances.

This is a method for the generic function `crossdist`

for point patterns (objects of class `"ppp"`

).

This function expects two
point patterns `X`

and `Y`

, and returns the matrix
whose `[i,j]`

entry is the distance from `X[i]`

to
`Y[j]`

.

Alternatively if `periodic=TRUE`

, then provided the windows
containing `X`

and `Y`

are identical and are rectangular,
then the distances will be computed in the `periodic'
sense (also known as `torus' distance): opposite edges of the
rectangle are regarded as equivalent.
This is meaningless if the window is not a rectangle.
The argument `method`

is not normally used. It is
retained only for checking the validity of the software.
If `method = "interpreted"`

then the distances are
computed using interpreted R code only. If `method="C"`

(the default) then C code is used.
The C code is faster by a factor of 4.

##### Value

- A matrix whose
`[i,j]`

entry is the distance from the`i`

-th point in`X`

to the`j`

-th point in`Y`

.

##### See Also

`crossdist`

,
`crossdist.default`

,
`crossdist.psp`

,
`pairdist`

,
`nndist`

,
`Gest`

##### Examples

```
data(cells)
d <- crossdist(cells, runifpoint(6))
d <- crossdist(cells, runifpoint(6), periodic=TRUE)
```

*Documentation reproduced from package spatstat, version 1.11-7, License: GPL version 2 or newer*