R/remove_outliers.R

In stineb/ingestr: Environmental point data ingest

#' Remove outliers
#'
#' Removes outliers based on their distance from the inter-quartile range (IQR).
#' Excludes all points beyond \code{coef} times the IQR. The function uses the
#' command \code{boxplot.stats()} which uses the Tukey's method to identify the
#' outliers ranged above and below the \code{coef*}IQR.
#' 
#' @param vec A vector of numeric values
#' @param coef A number specifying the maximum distance from the 
#'  inter-quartile range of \code{vec} for which values in \code{vec} are not
#'  replaced with NA.
#' 
#' @return A vector of numeric values of length \code{length(vec)} with all
#'  elements identical as in \code{vec} except that outliers are replaced by NA.
#' @export
#'
#' @examples 
#' \dontrun{
#' vec <- remove_outliers( vec, coef=3 ) 
#' }
remove_outliers <- function(vec, coef = 1.5) {
  # use the command boxplot.stats()$out which use the Tukey's method to 
  # identify the outliers ranged above and below the <coef`>*IQR.
  outlier <- grDevices::boxplot.stats( vec, coef=coef )$out
  vec[ which( is.element( vec, outlier ) ) ] <- NA
  return( vec )
}