R/pl.R

In toniprice/jute: Sundry Utility Functions

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#' Pluralise word
#'
#' Converts a word into a plural (English).
#'
#' @param singular Singular form of the word
#' @param num Number of items. \code{num = 1} will give the singular form;
#'   \code{num = 0} or \code{num > 1} will give the plural form.
#' @param irregular Plural form of the word in the case where it is irregular
#'   and needs to be explicitly specified.
#'
#' @details
#' This function would usually be used in a context where the number of items
#'   \code{num} is a variable and not known at run-time.
#'
#' @return Either the singular or plural form of the word, depending on the
#'   value of \code{num}.
#'
#' @examples
#' pl("shoe", 2)
#' pl("shoe", 1)
#'
#' n <- 0
#' pl("thing", n)
#'
#' pl("sheep", 5) # => incorrect (gives "sheeps")
#' pl("sheep", 5, "sheep") # => correct   (gives "sheep")
#'
#' @export
#'
pl <- function(singular, num, irregular = NULL) {
  if (num == 1) {
    return(singular)
  }
  irregular %||% sprintf("%ss", singular)
}

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