R/has_element.R

In mlr3misc: Helper Functions for 'mlr3'

#' @title Check if an Object is Element of a List
#'
#' @description
#' Simply checks if a list contains a given object.
#'
#' * NB1: Objects are compared with identity.
#' * NB2: Only use this on lists with complex objects, for simpler structures there are faster operations.
#' * NB3: Clones of R6 objects are not detected.
#'
#' @inheritParams map
#' @param .y (`any`)\cr
#'   Object to test for.
#' @export
#' @examples
#' has_element(list(1, 2, 3), 1)
has_element = function(.x, .y) {
  for (i in seq_along(.x)) {
    if (identical(.x[[i]], .y)) {
      return(TRUE)
    }
  }
  return(FALSE)
}