# crossdist.default

##### Pairwise distances between two different sets of points

Computes the distances between each pair of points taken from two different sets of points.

##### Usage

```
## S3 method for class 'default':
crossdist(X, Y, x2, y2, \dots, period=NULL, method="C")
```

##### Arguments

- X,Y
- Numeric vectors of equal length specifying the coordinates of the first set of points.
- x2,y2
- Numeric vectors of equal length specifying the coordinates of the second set of points.
- ...
- Ignored.
- period
- Optional. Dimensions for periodic edge correction.
- method
- String specifying which method of calculation to use.
Values are
`"C"`

and`"interpreted"`

.

##### Details

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

This is a method for the generic function `crossdist`

.

This function expects `X`

and `Y`

to be numeric vectors
of equal length specifying the coordinates of the first set of points.
The arguments `x2`

,`y2`

specify the coordinates of the
second set of points.
Alternatively if `period`

is given,
then the distances will be computed in the `periodic'
sense (also known as `torus' distance).
The points will be treated as if they are in a rectangle
of width `period[1]`

and height `period[2]`

.
Opposite edges of the rectangle are regarded as equivalent.
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 the first set of points to the`j`

-th point in the second set of points.

##### See Also

`crossdist`

,
`crossdist.ppp`

,
`crossdist.psp`

,
`pairdist`

,
`nndist`

,
`Gest`

##### Examples

```
d <- crossdist(runif(7), runif(7), runif(12), runif(12))
d <- crossdist(runif(7), runif(7), runif(12), runif(12), period=c(1,1))
```

*Documentation reproduced from package spatstat, version 1.9-2, License: GPL version 2 or newer*