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Decimal to Roman Numeral

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Join Date: Feb 2009

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curiouskitten curiouskitten is offline

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Decimal to Roman Numeral

Feb 27th, 2009

I need to convert a number (in decimal form) that is between 1 to 4999 to Roman Numeral Form. However, though the code I have is kinda working, its only outputting the thousand digit, not anything less or any part thats less.

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
def int2roman(number):
    numerals={1:"I", 4:"IV", 5:"V", 9: "IX", 10:"X", 40:"XL", 50:"L",
              90:"XC", 100:"C", 400:"CD", 500:"D", 900:"CM", 1000:"M"}
    result=""
    for value, numeral in sorted(numerals.items(), reverse=True):
        while number >= value:
            result += numeral
            number -= value
        return result
print int2roman(input("Enter a number (1 to 4999) in decimal form: "))
def int2roman(number):
    numerals={1:"I", 4:"IV", 5:"V", 9: "IX", 10:"X", 40:"XL", 50:"L",
              90:"XC", 100:"C", 400:"CD", 500:"D", 900:"CM", 1000:"M"}
    result=""
    for value, numeral in sorted(numerals.items(), reverse=True):
        while number >= value:
            result += numeral
            number -= value
        return result
print int2roman(input("Enter a number (1 to 4999) in decimal form: "))

if I input 1994, I get M instead of the MCMXCIV I should be getting. Any corrections and explanations to my code?
Thanks

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Re: Decimal to Roman Numeral

Feb 27th, 2009

Here is a site where they do just what you are doing, the first bit talks about unit testing, just ignore that and keep going on, it shows you how to make a roman numeral converter that is almost impossible to break:
http://www.diveintopython.org/unit_testing/index.html

Make it idiot proof and someone will make a better idiot.
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Re: Decimal to Roman Numeral

Feb 27th, 2009

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Originally Posted by curiouskitten

Any corrections and explanations to my code?

Your return statement is inside your for loop so it's exiting on the first iteration.... if you knock it back an indentation level it'll work:

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
>>> def int2roman(number):
...     numerals={1:"I", 4:"IV", 5:"V", 9: "IX", 10:"X", 40:"XL", 50:"L",
...               90:"XC", 100:"C", 400:"CD", 500:"D", 900:"CM", 1000:"M"}
...     result=""
...     for value, numeral in sorted(numerals.items(), reverse=True):
...         while number >= value:
...             result += numeral
...             number -= value
...     return result
...     
>>> print int2roman(input("Enter a number (1 to 4999) in decimal form: "))
Enter a number (1 to 4999) in decimal form: 1942
MCMXLII
>>> print int2roman(input("Enter a number (1 to 4999) in decimal form: "))
Enter a number (1 to 4999) in decimal form: 1994
MCMXCIV
>>> def int2roman(number):
...     numerals={1:"I", 4:"IV", 5:"V", 9: "IX", 10:"X", 40:"XL", 50:"L",
...               90:"XC", 100:"C", 400:"CD", 500:"D", 900:"CM", 1000:"M"}
...     result=""
...     for value, numeral in sorted(numerals.items(), reverse=True):
...         while number >= value:
...             result += numeral
...             number -= value
...     return result
...     
>>> print int2roman(input("Enter a number (1 to 4999) in decimal form: "))
Enter a number (1 to 4999) in decimal form: 1942
MCMXLII
>>> print int2roman(input("Enter a number (1 to 4999) in decimal form: "))
Enter a number (1 to 4999) in decimal form: 1994
MCMXCIV

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Re: Decimal to Roman Numeral

Feb 27th, 2009

•

Originally Posted by curiouskitten

I need to convert a number (in decimal form) that is between 1 to 4999 to Roman Numeral Form. However, though the code I have is kinda working, its only outputting the thousand digit, not anything less or any part thats less.
Help with Code Tags

Python Syntax (Toggle Plain Text)
def int2roman(number):
    numerals={1:"I", 4:"IV", 5:"V", 9: "IX", 10:"X", 40:"XL", 50:"L",
              90:"XC", 100:"C", 400:"CD", 500:"D", 900:"CM", 1000:"M"}
    result=""
    for value, numeral in sorted(numerals.items(), reverse=True):
        while number >= value:
            result += numeral
            number -= value
        return result
print int2roman(input("Enter a number (1 to 4999) in decimal form: "))
def int2roman(number): numerals={1:"I", 4:"IV", 5:"V", 9: "IX", 10:"X", 40:"XL", 50:"L", 90:"XC", 100:"C", 400:"CD", 500:"D", 900:"CM", 1000:"M"} result="" for value, numeral in sorted(numerals.items(), reverse=True): while number >= value: result += numeral number -= value return result print int2roman(input("Enter a number (1 to 4999) in decimal form: "))
if I input 1994, I get M instead of the MCMXCIV I should be getting. Any corrections and explanations to my code?
Thanks

You are almost there, your return statement needs to be outside the for loop.

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
def int2roman(number):
    numerals={1:"I", 4:"IV", 5:"V", 9: "IX", 10:"X", 40:"XL", 50:"L",
              90:"XC", 100:"C", 400:"CD", 500:"D", 900:"CM", 1000:"M"}
    result=""
    for value, numeral in sorted(numerals.items(), reverse=True):
        while number >= value:
            result += numeral
            number -= value
    return result
 
print int2roman(input("Enter a number (1 to 4999) in decimal form: "))
def int2roman(number):
    numerals={1:"I", 4:"IV", 5:"V", 9: "IX", 10:"X", 40:"XL", 50:"L",
              90:"XC", 100:"C", 400:"CD", 500:"D", 900:"CM", 1000:"M"}
    result=""
    for value, numeral in sorted(numerals.items(), reverse=True):
        while number >= value:
            result += numeral
            number -= value
    return result

print int2roman(input("Enter a number (1 to 4999) in decimal form: "))

Sorry, didn't see Pen's early response.