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59 lines
2.6 KiB
R
59 lines
2.6 KiB
R
# ==================================================================== #
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# TITLE #
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# Antimicrobial Resistance (AMR) Analysis #
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# #
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# AUTHORS #
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# Berends MS (m.s.berends@umcg.nl), Luz CF (c.f.luz@umcg.nl) #
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# #
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# LICENCE #
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# This package is free software; you can redistribute it and/or modify #
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# it under the terms of the GNU General Public License version 2.0, #
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# as published by the Free Software Foundation. #
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# #
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# This R package is distributed in the hope that it will be useful, #
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# but WITHOUT ANY WARRANTY; without even the implied warranty of #
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the #
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# GNU General Public License version 2.0 for more details. #
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# ==================================================================== #
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#' Skewness of the sample
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#'
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#' @description Skewness is a measure of the asymmetry of the probability distribution of a real-valued random variable about its mean.
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#'
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#' 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.
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#' @param x a vector of values, a \code{matrix} or a \code{data frame}
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#' @param na.rm a logical value indicating whether \code{NA} values should be stripped before the computation proceeds.
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#' @exportMethod skewness
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#' @seealso \code{\link{kurtosis}}
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#' @rdname skewness
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#' @export
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skewness <- function(x, na.rm = FALSE) {
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UseMethod("skewness")
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}
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#' @exportMethod skewness.default
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#' @rdname skewness
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#' @export
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skewness.default <- function (x, na.rm = FALSE) {
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x <- as.vector(x)
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if (na.rm == TRUE) {
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x <- x[!is.na(x)]
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}
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n <- length(x)
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(base::sum((x - base::mean(x))^3) / n) / (base::sum((x - base::mean(x))^2) / n)^(3/2)
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}
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#' @exportMethod skewness.matrix
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#' @rdname skewness
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#' @export
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skewness.matrix <- function (x, na.rm = FALSE) {
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base::apply(x, 2, skewness.default, na.rm = na.rm)
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}
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#' @exportMethod skewness.data.frame
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#' @rdname skewness
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#' @export
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skewness.data.frame <- function (x, na.rm = FALSE) {
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base::sapply(x, skewness.default, na.rm = na.rm)
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}
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