Pcolar
commented
10 years ago I found some code at: http://code.activestate.com/recipes/81611-roman-numerals/
def roman_to_int(input): """ Convert a roman numeral to an integer.
r = range(1, 4000) nums = [int_to_roman(i) for i in r] ints = [roman_to_int(n) for n in nums] print r == ints 1
roman_to_int('VVVIV') Traceback (most recent call last): ... ValueError: input is not a valid roman numeral: VVVIV roman_to_int(1) Traceback (most recent call last): ... TypeError: expected string, got roman_to_int('a') Traceback (most recent call last): ... ValueError: input is not a valid roman numeral: A roman_to_int('IL') Traceback (most recent call last): ... ValueError: input is not a valid roman numeral: IL """ try: input = input.upper() except AttributeError: raise TypeError, 'expected string, got %s' % type(input)
map of (numeral, value, maxcount) tuples
roman_numeral_map = (('M', 1000, 3), ('CM', 900, 1), ('D', 500, 1), ('CD', 400, 1), ('C', 100, 3), ('XC', 90, 1), ('L', 50, 1), ('XL', 40, 1), ('X', 10, 3), ('IX', 9, 1), ('V', 5, 1), ('IV', 4, 1), ('I', 1, 3)) result, index = 0, 0 for numeral, value, maxcount in roman_numeral_map: count = 0 while input[index: index +len(numeral)] == numeral: count += 1 # how many of this numeral we have if count > maxcount: raise ValueError, 'input is not a valid roman numeral: %s' % input result += value index += len(numeral) if index < len(input): # There are characters unaccounted for. raise ValueError, 'input is not a valid roman numeral: %s'%input else: return result
Function to convert roman numerals to digits
i.e. IX -> 9