# 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 class 'ppp':
crossdist(X, Y, \dots, 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.