pairdist.ppp

0th

Percentile

Pairwise distances

Computes the matrix of distances between all pairs of points in a point pattern.

Keywords
spatial, math
Usage
# S3 method for ppp
pairdist(X, …, periodic=FALSE, method="C", squared=FALSE)
Arguments
X

A point pattern (object 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". Usually not specified.

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 point pattern X (an object of class "ppp"), 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 rectangle, 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.

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).

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 somewhat faster.

Value

A square matrix whose [i,j] entry is the distance between the points numbered i and j.

See Also

pairdist, pairdist.default, pairdist.psp, crossdist, nndist, Kest

Aliases
  • pairdist.ppp
Examples
# NOT RUN {
   data(cells)
   d <- pairdist(cells)
   d <- pairdist(cells, periodic=TRUE)
   d <- pairdist(cells, squared=TRUE)
# }
Documentation reproduced from package spatstat, version 1.56-1, License: GPL (>= 2)

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