R/geoMean.R

In TalhoukLab/biostatUtil: Utility Functions Used in Biostatistics Projects

#' Geometric mean
#'
#' Calculates the geometric mean
#'
#' @param x a vector. Matrices are allowed.
#' @param na.rm logical; should NA values be removed?
#' @return If `x` has any `NA` values then `geoMean` will return
#'   `NA` just like `mean` unless `na.rm = TRUE` is specified.
#'   Otherwise, the geometric mean of `x` is returned. If the input only
#'   has `NA` values then `NA` is returned as well.
#' @author Samuel Leung, Derek Chiu
#' @export
#' @examples
#' set.seed(1)
#' x <- rexp(100, rate = 0.5)
#' y <- rexp(100, rate = 0.3)
#' y[3] <- NA
#' geoMean(x)
#' geoMean(y)
#' geoMean(y, na.rm = TRUE)
geoMean <- function(x, na.rm = FALSE) {
  if (na.rm) {
    x <- x[!is.na(x)]
    if (length(x) > 0)
      result <- prod(x) ^ (1 / length(x))
    else
      result <- NA
  } else {
    result <- prod(x) ^ (1 / length(x))
  }
  return(result)
}