"""
Light-weight functions to convert from Roman-Numerals to ints,
and vice-versa.
"""
#import string
factor_list = [1000, 500, 100, 50, 10, 5, 1]
roman_equiv = {1000: 'M', 500: 'D', 100: 'C', 50: 'L', 10: 'X', 5: 'V', 1: 'I'}
def IToRoman(num):
roman = ""
remainder = num
factor_index = 0
for f in factor_list:
factor_up = (f != 1000 and factor_list[factor_index - 1]) or None
factor_down = (f != 1 and factor_list[factor_index + 1]) or None
dividend = remainder / f
remainder = remainder % f
if factor_up and dividend == 4:
roman = roman + roman_equiv[f] + roman_equiv[factor_up]
elif factor_down and dividend == 1 and remainder / factor_down == 4:
roman = roman + roman_equiv[factor_down] + roman_equiv[factor_up]
remainder = remainder % factor_down
else:
roman = roman + roman_equiv[f]*dividend
factor_index = factor_index + 1
return roman
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