distance {laGP}

Calculate the squared Euclidean distance between pairs of points

Description

Calculate the squared Euclidean distance between pairs of points and return a distance matrix

Usage

distance(X1, X2 = NULL)

Arguments

X1

a matrix or data.frame containing real-valued numbers

X2

an optional matrix or data.frame containing real-valued numbers; must have ncol(X2) = ncol(X1)

Details

If X2 = NULL distances between X1 and itself are calculated, resulting in an nrow(X1)-by-nrow(X1) distance matrix. Otherwise the result is nrow(X1)-by-nrow(X2) and contains distances between X1 and X2.

Calling distance(X) is the same as distance(X,X)

Value

The output is a matrix, whose dimensions are described in the Details section above

Author(s)

Robert B. Gramacy [e-mail]

See Also

darg

Examples

x <- seq(-2, 2, length=11)
X <- as.matrix(expand.grid(x, x))
## predictive grid with NN=400
xx <- seq(-1.9, 1.9, length=20)
XX <- as.matrix(expand.grid(xx, xx))

D <- distance(X)
DD <- distance(X, XX)