R: Pairwise distances between two different sets of points

crossdist.default {spatstat.geom} | R Documentation

## Pairwise distances between two different sets of points

### Description

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

### Usage

      ## Default S3 method:
    crossdist(X, Y, x2, y2, ...,
                 period=NULL, method="C", squared=FALSE)

### 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"`.
`squared` | Logical. If `squared=TRUE`, the squared distances are returned instead (this computation is faster).

### 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.

### Author(s)

Pavel Grabarnik pavel.grabar@issp.serpukhov.su and Adrian Baddeley Adrian.Baddeley@curtin.edu.au

### 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))

[Package spatstat.geom version 2.3-2 Index]