R/pluralise.R

In moj-analytical-services/mojrap: Generic Functions for Reproducible Analytical Pipelines in MoJ

#' Pluralise words depending on a value
#'
#' This function takes a given value and outputs whether a word needs to be pluralised based on the value of the input:
#' if the value is 1, the output is not pluralised, if the value is > 1, the output is pluralised.
#' The function can either pluralise a specific input word, or the output be used next to an existing word (if the word parameter is left blank).
#' NB - this function simply adds an 's' to pluralise; for more complex pluralisations (e.g. 'ies' rather than 'ys') this function will not provide desired output.
#'
#' @param value the integer value preceeding your word which needs to be checked for if pluralisation is required
#' @param word the word that you wish to pluralise. Optional, defaults to blank - if blank, the function outputs an 's' (if pluralisation required)
#' to add to the end of an existing word
#'
#' @examples
#' pluralise(4, "percentage point") # outputs string "percentage points"
#' pluralise(1, "week") # outputs string "week"
#' pluralise(2) # outputs string "s"
#' pluralise(1) # outputs blank string ""
#' pluralise(-5, "week") # outputs string "weeks"
#'
#' @export

pluralise   <- function(value, word = ""){

  value <- abs(value)

  #CHECKS
  if (value == 0){

    stop("the value is zero and thus pluralisation does not make sense. Please enter an integer value greater than zero")

  } else if (is.numeric(value) != TRUE){

    stop("value argument must be an integer, in order to determine whether pluralisation is required")

  } else {  }

  if (is.character(word) != TRUE){

    stop("the word you enter must be a character string")

  } else {}

  #BODY
  if (value == 1){

    if (word == ""){

      out <- ""

    } else {

      out <- word

    }
  } else if (value > 1){

    if (word == ""){

      out <- "s"

    } else {

      out <- paste(word, "s", sep = "")

    }
  }

  return(out)

}