R/num2words.R

In dietrichson/sashaUseful: Collection of Useful Functions

#' Convert Number to Word
#'
#' Convert a number to word.
#'
#' @param x 
#' @param first.cap Should the first word be capitalized (i.e. start of a sentence)
#' @import stringr
#' @return a string 
#' @export
num2words <- function(x, first.cap=FALSE){
  ## Function by John Fox found here: 
  ## http://tolstoy.newcastle.edu.au/R/help/05/04/2715.html
  ## Tweaks by AJH to add commas and "and"
  helper <- function(x){
    
    digits <- rev(strsplit(as.character(x), "")[[1]])
    nDigits <- length(digits)
    if (nDigits == 1) as.vector(ones[digits])
    else if (nDigits == 2)
      if (x <= 19) as.vector(teens[digits[1]])
    else trim(paste(tens[digits[2]],
                    Recall(as.numeric(digits[1]))))
    else if (nDigits == 3) trim(paste(ones[digits[3]], "hundred and", 
                                      Recall(makeNumber(digits[2:1]))))
    else {
      nSuffix <- ((nDigits + 2) %/% 3) - 1
      if (nSuffix > length(suffixes)) stop(paste(x, "is too large!"))
      trim(paste(Recall(makeNumber(digits[
        nDigits:(3*nSuffix + 1)])),
        suffixes[nSuffix],"," ,
        Recall(makeNumber(digits[(3*nSuffix):1]))))
    }
  }
  trim <- function(text){
    #Tidy leading/trailing whitespace, space before comma
    text=gsub("^\ ", "", gsub("\ *$", "", gsub("\ ,",",",text)))
    #Clear any trailing " and"
    text=gsub(" and$","",text)
    #Clear any trailing comma
    gsub("\ *,$","",text)
  }  
  makeNumber <- function(...) as.numeric(paste(..., collapse=""))     
  #Disable scientific notation
  opts <- options(scipen=100) 
  on.exit(options(opts)) 
  ones <- c("", "one", "two", "three", "four", "five", "six", "seven",
            "eight", "nine") 
  names(ones) <- 0:9 
  teens <- c("ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen",
             "sixteen", " seventeen", "eighteen", "nineteen")
  names(teens) <- 0:9 
  tens <- c("twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty",
            "ninety") 
  names(tens) <- 2:9 
  x <- round(x)
  suffixes <- c("thousand", "million", "billion", "trillion")     
  if (length(x) > 1) return(trim(sapply(x, helper)))
  ret <- helper(x)
  if(isTRUE(first.cap))
    ret <- stringr::str_to_sentence(ret) #Not quite TODO: fix later so it is 
  ret
}