spell.py

# code stole from: https://stackoverflow.com/a/54018199/21613605

ones = {
    0: '', 1: 'one', 2: 'two', 3: 'three', 4: 'four', 5: 'five', 6: 'six',
    7: 'seven', 8: 'eight', 9: 'nine', 10: 'ten', 11: 'eleven', 12: 'twelve',
    13: 'thirteen', 14: 'fourteen', 15: 'fifteen', 16: 'sixteen',
    17: 'seventeen', 18: 'eighteen', 19: 'nineteen'}
tens = {
    2: 'twenty', 3: 'thirty', 4: 'forty', 5: 'fifty', 6: 'sixty',
    7: 'seventy', 8: 'eighty', 9: 'ninety'}
illions = {
    1: 'thousand', 2: 'million', 3: 'billion', 4: 'trillion', 5: 'quadrillion',
    6: 'quintillion', 7: 'sextillion', 8: 'septillion', 9: 'octillion',
    10: 'nonillion', 11: 'decillion'}



def say_number(i):
    """
    Convert an integer in to it's word representation.

    say_number(i: integer) -> string
    """
    if i < 0:
        return _join('negative', _say_number_pos(-i))
    if i == 0:
        return 'zero'
    return _say_number_pos(i)


def _say_number_pos(i):
    if i < 20:
        return ones[i]
    if i < 100:
        return _join(tens[i // 10], ones[i % 10])
    if i < 1000:
        return _divide(i, 100, 'hundred')
    for illions_number, illions_name in illions.items():
        if i < 1000**(illions_number + 1):
            break
    return _divide(i, 1000**illions_number, illions_name)


def _divide(dividend, divisor, magnitude):
    return _join(
        _say_number_pos(dividend // divisor),
        magnitude,
        _say_number_pos(dividend % divisor),
    )


def _join(*args):
    return ' '.join(filter(bool, args))

if __name__ == "__main__":
  def test_say_number(data, expected_output):
      """Test cases for say_number(i)."""
      output = say_number(data)
      assert output == expected_output, \
          "\n    for:      {}\n    expected: {}\n    got:      {}".format(
              data, expected_output, output)


  test_say_number(0, 'zero')
  test_say_number(1, 'one')
  test_say_number(-1, 'negative one')
  test_say_number(10, 'ten')
  test_say_number(11, 'eleven')
  test_say_number(99, 'ninety nine')
  test_say_number(100, 'one hundred')
  test_say_number(111, 'one hundred eleven')
  test_say_number(999, 'nine hundred ninety nine')
  test_say_number(1119, 'one thousand one hundred nineteen')
  test_say_number(999999,
                  'nine hundred ninety nine thousand nine hundred ninety nine')
  test_say_number(9876543210,
                  'nine billion eight hundred seventy six million '
                  'five hundred forty three thousand two hundred ten')
  test_say_number(1000**1, 'one thousand')
  test_say_number(1000**2, 'one million')
  test_say_number(1000**3, 'one billion')
  test_say_number(1000**4, 'one trillion')
  test_say_number(1000**5, 'one quadrillion')
  test_say_number(1000**6, 'one quintillion')
  test_say_number(1000**7, 'one sextillion')
  test_say_number(1000**8, 'one septillion')
  test_say_number(1000**9, 'one octillion')
  test_say_number(1000**10, 'one nonillion')
  test_say_number(1000**11, 'one decillion')
  test_say_number(1000**12, 'one thousand decillion')
  test_say_number(
      1-1000**12,
      'negative nine hundred ninety nine decillion nine hundred ninety nine '
      'nonillion nine hundred ninety nine octillion nine hundred ninety nine '
      'septillion nine hundred ninety nine sextillion nine hundred ninety nine '
      'quintillion nine hundred ninety nine quadrillion nine hundred ninety '
      'nine trillion nine hundred ninety nine billion nine hundred ninety nine'
      ' million nine hundred ninety nine thousand nine hundred ninety nine')