R/crossdistsph.R

In baddstats/spherstat: Spatial Point Pattern Analysis, Geometry and Trigonometry for the Sphere

crossdistsph <- function(X, Y, rad=1) {
	stopifnot(inherits(X, c("sp2", "sp3", "matrix")) && inherits(Y, c("sp2", "sp3", "matrix")))
	if(inherits(X, c("sp2", "sp3")) && inherits(Y, c("sp2", "sp3")) && X$win$rad != Y$win$rad) {
		stop("Objects have different rad values")
	}
	if(inherits(X, "matrix")) {
		X <- X
	}
	else {
		rad <- X$win$rad
		X <- X$X
	}
	if(inherits(Y, "matrix")) {
		Y <- Y
	}
	else {
		if(!inherits(Y, c("sp2", "sp3"))) {
			rad <- Y$rad
		}
		Y <- Y$X
	}
	nrX <- nrow(X)
	nrY <- nrow(Y)
	if(ncol(X)==2) {
		X <- convert3(X)
	}
	if(ncol(Y)==2) {
		Y <- convert3(Y)
	}
	if(nrX==0 && nrY==0) {
		d <- NA
	}
	else {
        	XY <- X %*% t(Y)
        	d <- rad * acos(pmin(1, pmax(-1, XY/rad))/rad)
	}
	d <- matrix(d, nrow=nrX, ncol=nrY)         
	return(d)
}