R/notIn.R

In anilchalisey/juggleR: A mix of useful R functions

#' @title Not in
#'
#' @description Determine if values in the first argument don't exist in the second argument.
#'
#' @details
#' \code{\%nin\%} is the functional inverse of \code{\%in\%}.
#' \code{lhs \%nin\% rhs} is equivalent to \code{notIn(lhs, rhs)}.
#'
#' @param x Vector or NULL: the values to be matched.
#' @param y Vector or NULL: the values to be matched against.
#' @return A logical vector of the same length as \code{x}. For every element in \code{x},
#' return \code{FALSE} if the value exists in \code{y}, and \code{TRUE} otherwise.
#'
#' @examples
#' "a" %nin% letters
#' "a" %nin% LETTERS
#' c("a", "A") %nin% letters
#' notIn("A", letters)
#'
#' @name notIn
NULL

#' @export
#' @rdname notIn
"%nin%" <- function(x, y) {
  notIn(x, y)
}

#' @export
#' @rdname notIn
notIn <- function(x, y) {
  stopifnot((is.vector(x) || is.null(x)) &&
              (is.vector(y) || is.null(y)))
  !(x %in% y)
}