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Mark Pilgrim's library solution in Clear category for Roman Numerals by macfreek
#!/usr/bin/env python3.2
# -*- coding: utf-8 -*-
__author__ = "Mark Pilgrim (mark@diveintopython.org)"
__version__ = "$Revision: 1.3 $"
__date__ = "$Date: 2004/05/05 21:57:19 $"
__copyright__ = "Copyright (c) 2001 Mark Pilgrim"
__license__ = "Python"
import re
#Define exceptions
class RomanError(Exception): pass
class OutOfRangeError(RomanError): pass
class NotIntegerError(RomanError): pass
class InvalidRomanNumeralError(RomanError): pass
# WARNING: Disabled XL to adhere to malformed roman numerals as used by Victory!
# Define digit mapping
romanNumeralMap = (('M', 1000),
('CM', 900),
('D', 500),
('CD', 400),
('C', 100),
('XC', 90),
('L', 50),
('XL', 40),
('X', 10),
('IX', 9),
('V', 5),
('IV', 4),
('I', 1))
def toRoman(n):
"""convert integer to Roman numeral"""
if not (0 < n < 5000):
raise OutOfRangeError("number out of range (must be 1..4999)")
if int(n) != n:
raise NotIntegerError("non-integers can not be converted")
result = ""
for numeral, integer in romanNumeralMap:
while n >= integer:
result += numeral
n -= integer
return result
# Define pattern to detect valid Roman numerals
romanNumeralPattern = re.compile('''
^ # beginning of string
M{0,4} # thousands - 0 to 4 M's
(CM|CD|D?C{0,5}) # hundreds - 900 (CM), 400 (CD), 0-300 (0 to 3 C's),
# or 500-800 (D, followed by 0 to 3 C's)
(XC|XL|L?X{0,5}) # tens - 90 (XC), 40 (XL), 0-30 (0 to 3 X's),
# or 50-80 (L, followed by 0 to 3 X's)
(IX|IV|V?I{0,5}) # ones - 9 (IX), 4 (IV), 0-3 (0 to 3 I's),
# or 5-8 (V, followed by 0 to 3 I's)
$ # end of string
''' ,re.VERBOSE)
def fromRoman(s):
"""convert Roman numeral to integer"""
if not s:
raise InvalidRomanNumeralError('Input can not be blank')
if not romanNumeralPattern.search(s):
raise InvalidRomanNumeralError('Invalid Roman numeral: %s' % s)
result = 0
index = 0
for numeral, integer in romanNumeralMap:
while s[index:index+len(numeral)] == numeral:
result += integer
index += len(numeral)
return result
checkio = toRoman
if __name__ == '__main__':
assert checkio(6) == 'VI', 'First'
assert checkio(76) == 'LXXVI', 'Second'
assert checkio(499) == 'CDXCIX', 'Third'
assert checkio(3888) == 'MMMDCCCLXXXVIII', 'Fourth'
print('All ok')
Dec. 15, 2012
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