R/geoR_trf.R

In famuvie/geoRcb: An Extension of Package geoR that Works with Cost-Based Distances

#' Default transition function in geoR
#'
#' Default function to use with \code{\link[gdistance]{transition}}. Defined as
#' the geometric mean.
#'
#' To use another function, override this one by defining it using the same
#' name.
#'
#' @param x numeric vector of length 2 with cost/conductivity non-negative
#'   numbers.
#'
#' @return cost/conductivity value of the transition between neighbouring cells.
#' @export
#' @examples
#'    geoR_trf(c(0, 1))
#'
#'    # redefine function
#'    geoR_trf <- mean
#'
#'    geoR_trf(c(0, 1))
geoR_trf <- function(x) {
  stopifnot(length(x) == 2)
  sqrt(prod(x))
}