R/remove_outliers.r

In robertzk/syberiaMungebits: Common mungebits used with Syberia projects.

#' remove outliers based upon a z_score threshold z_score=> (x - mean(x) / sd(x) 
#'
#' @param x an numeric vector
#' @param threshold a z_score threshold from which the absolute value of a z_score above this threshold will be set to NA 

remove_outliers_fn <- function(x, threshold = 3) {
  if (!('removed_outliers' %in% names(inputs))) {
    inputs$mean <<- mean(x, na.rm = TRUE)
    inputs$sd <<- sd(x, na.rm = TRUE) 
    inputs$removed_outliers <<- TRUE  ## not sure if another mungebit has a mean namespace 
  }
  x[abs((x - inputs$mean) / inputs$sd) > threshold] <- NA
  x
}

#' @export
remove_outliers <- column_transformation(remove_outliers_fn, mutating = TRUE)