calcFunctions4.py

from math import factorial as fact


def factorial(numStr):
    try:
        n = int(numStr)
        r = str(fact(n))
    except:
        r = 'Error!'
    return r


def decToBin(numStr):
    try:
        n = int(numStr)
        r = bin(n)[2:]
    except:
        r = 'Error!'
    return r


def binToDec(numStr):
    try:
        n = int(numStr, 2)
        r = str(n)
    except:
        r = 'Error!'
    return r


def decToRoman(numStr):
    try:
        n = int(numStr)
    except:
        return 'Error!'

    if n >= 4000:
        return 'Error!'

    romans = [
        (1000, 'M'), (900, 'CM'), (500, 'D'), (400, 'CD'),
        (100, 'C'), (90, 'XC'), (50, 'L'), (40, 'XL'),
        (10, 'X'), (9, 'IX'), (5, 'V'), (4, 'IV'),
        (1, 'I')
    ]

    result = ''
    for value, letters in romans:
        while n >= value:
            result += letters
            n -= value

    return result


def romanToDec(numStr):
    values = (('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))
    result = 0
    number = []
    try:
        n = str(numStr)
        for i in range(len(numStr)):
            for roman, num in values:
                while True:
                    if numStr[i] == roman:
                        number.append(num)
                    break
        number.append(0)
        for i in range(len(numStr)):
            if number[i] >= number[i + 1]:
                result = result + number[i]
            else:
                result = result - number[i]
    except:
        return 'Error!'

    return result