median <- function(x, na.rm = FALSE) {
	if(na.rm)
		x <- x[!is.na(x)]
	else if(any(is.na(x)))
		return(NA)
	n <- length(x)
	half <- (n + 1)/2
	if(n %% 2 == 1) {
		sort(x, partial = half)[half]
	}
	else {
		sum(sort(x, partial = c(half, half + 1))[c(half, half + 1)])/2
	}
}
