crossdist.ppp

0th

Percentile

Pairwise distances between two different point patterns

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

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

squared

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

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.

Aliases
• crossdist.ppp
Examples
# NOT RUN {
data(cells)
d <- crossdist(cells, runifpoint(6))
d <- crossdist(cells, runifpoint(6), periodic=TRUE)
# }
Documentation reproduced from package spatstat, version 1.55-1, License: GPL (>= 2)

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