R/dist_cross.r

In orthoDr: Semi-Parametric Dimension Reduction Models Using Orthogonality Constrained Optimization

#' Cross distance matrix
#' 
#' Calculate the Gaussian kernel distance between rows of X1 and rows of X2.
#' As a result, this is an extension to the [stats::dist()] function. 
#' 
#' @param x1 First data matrix
#' @param x2 Second data matrix
#' 
#' @return 
#' A distance matrix with its (i, j)th element being the Gaussian kernel
#' distance between ith row of `X1` jth row of `X2`.
#' 
#' @export
#' 
#' @examples
#' # two matrices
#' set.seed(1)
#' x1 <- matrix(rnorm(10), 5, 2)
#' x2 <- matrix(rnorm(6), 3, 2)
#' dist_cross(x1, x2)
dist_cross <- function(x1, x2) {
  if (!is.matrix(x1) | !is.numeric(x1)) stop("x1 must be a numerical matrix")
  if (!is.matrix(x2) | !is.numeric(x2)) stop("x2 must be a numerical matrix")
  if (ncol(x1) != ncol(x2)) stop("x1 and x2 must have the same number of columns")

  return(KernelDist_cross(x1, x2))
}