mirror of https://github.com/msberends/AMR.git
41 lines
1.4 KiB
R
41 lines
1.4 KiB
R
|
#' Skewness of the sample
|
||
|
|
#'
|
||
|
|
#' @description Skewness is a measure of the asymmetry of the probability distribution of a real-valued random variable about its mean.
|
||
|
|
#'
|
||
|
|
#' When negative: the left tail is longer; the mass of the distribution is concentrated on the right of the figure. When positive: the right tail is longer; the mass of the distribution is concentrated on the left of the figure.
|
||
|
|
#' @param x a vector of values, a \code{matrix} or a \code{data frame}
|
||
|
|
#' @param na.rm a logical value indicating whether \code{NA} values should be stripped before the computation proceeds.
|
||
|
|
#' @exportMethod skewness
|
||
|
|
#' @seealso \code{\link{kurtosis}}
|
||
|
|
#' @rdname skewness
|
||
|
|
#' @export
|
||
|
|
skewness <- function(x, na.rm = FALSE) {
|
||
|
|
UseMethod("skewness")
|
||
|
|
}
|
||
|
|
|
||
|
|
#' @exportMethod skewness.default
|
||
|
|
#' @rdname skewness
|
||
|
|
#' @export
|
||
|
|
skewness.default <- function (x, na.rm = FALSE) {
|
||
|
|
x <- as.vector(x)
|
||
|
|
if (na.rm == TRUE) {
|
||
|
|
x <- x[!is.na(x)]
|
||
|
|
}
|
||
|
|
n <- length(x)
|
||
|
|
(base::sum((x - base::mean(x))^3) / n) / (base::sum((x - base::mean(x))^2) / n)^(3/2)
|
||
|
|
}
|
||
|
|
|
||
|
|
#' @exportMethod skewness.matrix
|
||
|
|
#' @rdname skewness
|
||
|
|
#' @export
|
||
|
|
skewness.matrix <- function (x, na.rm = FALSE) {
|
||
|
|
base::apply(x, 2, skewness.default, na.rm = na.rm)
|
||
|
|
}
|
||
|
|
|
||
|
|
#' @exportMethod skewness.data.frame
|
||
|
|
#' @rdname skewness
|
||
|
|
#' @export
|
||
|
|
skewness.data.frame <- function (x, na.rm = FALSE) {
|
||
|
|
base::sapply(x, skewness.default, na.rm = na.rm)
|
||
|
|
}
|