roman-numerals 4.1.0

Manipulate well-formed Roman numerals

A library for manipulating well-formed Roman numerals.

Integers between 1 and 3,999 (inclusive) are supported. Numbers beyond this range will return an OutOfRangeError.

The classical system of roman numerals requires that the same character may not appear more than thrice consecutively, meaning that ‘MMMCMXCIX’ (3,999) is the largest well-formed Roman numeral. The smallest is ‘I’ (1), as there is no symbol for zero in Roman numerals.

Both upper- and lower-case formatting of roman numerals are supported, and likewise for parsing strings, although the entire string must be of the same case. Numerals that do not adhere to the classical form are rejected with an InvalidRomanNumeralError.

Example usage

Creating a roman numeral

from roman_numerals import RomanNumeral

num = RomanNumeral(16)
assert str(num) == 'XVI'

num = RomanNumeral.from_string("XVI")
assert int(num) == 16

Convert a roman numeral to a string

from roman_numerals import RomanNumeral

num = RomanNumeral(16)
assert str(num) == 'XVI'
assert num.to_uppercase() == 'XVI'
assert num.to_lowercase() == 'xvi'
assert repr(num) == 'RomanNumeral(16)'

Extract the decimal value of a roman numeral

from roman_numerals import RomanNumeral

num = RomanNumeral(42)
assert int(num) == 42

Invalid input

from roman_numerals import RomanNumeral, InvalidRomanNumeralError

num = RomanNumeral.from_string("Spam!")  # raises InvalidRomanNumeralError
num = RomanNumeral.from_string("CLL")  # raises InvalidRomanNumeralError
num = RomanNumeral(0)  # raises OutOfRangeError
num = RomanNumeral(4_000)  # raises OutOfRangeError

Licence

This project is licenced under the terms of either the Zero-Clause BSD licence or the CC0 1.0 Universal licence. See LICENCE.rst for the full text of both licences.