I think this is pretty elegant, probably not "pythonic" though... clear solution for Roman Numerals by nathan.l.cook - python coding challenges

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I think this is pretty elegant, probably not "pythonic" though... solution in Clear category for Roman Numerals by nathan.l.cook

def checkio(data):
    dec = [1, 5, 10, 50, 100, 500, 1000]
    rom = ['I', 'V', 'X', 'L', 'C', 'D', 'M']
    str_data = str(data)
    str_data = str_data[::-1]
    num_digits = len(str_data)
    ans = ""
    rom_pointer = 0

    for place in range(num_digits):
        if str_data[place] in ["0", "1", "2", "3"]:
            ans = rom[rom_pointer] * int(str_data[place]) + ans
        elif str_data[place] in ["4"]:
             ans = rom[rom_pointer] + rom[rom_pointer + 1] + ans
        elif str_data[place] in ["5", "6", "7", "8"]:
             ans = rom[rom_pointer + 1] + rom[rom_pointer] * (int(str_data[place]) - 5) + ans
        elif str_data[place] in ["9"]:
             ans = rom[rom_pointer] + rom[rom_pointer + 2] + ans
        rom_pointer += 2

    return ans

if __name__ == '__main__':
    #These "asserts" using only for self-checking and not necessary for auto-testing
    assert checkio(6) == 'VI', '6'
    assert checkio(76) == 'LXXVI', '76'
    assert checkio(499) == 'CDXCIX', '499'
    assert checkio(3888) == 'MMMDCCCLXXXVIII', '3888'

Oct. 14, 2014

Comments:

nathan.l.cook on Oct. 14, 2014, 10:22 p.m.
Oops, "dec" is not required (it's from an earlier attempt). Ignore it.

veky on Nov. 10, 2014, 9:08 a.m.
Nice idea, but yes, Pythonicity suffers. For a Pythonic way of doing the same, see my solution. ;-= BTW, if you're interested, your solution can be condensed as <pre class='brush: python'>checkio = lambda n, R='MDCLXVI': "".join(R[2*i] * d if d < 4 else R[2*i] + R[2*i-1] if d == 4 else R[2*i-1] + R[2*i] * (d-5) if d < 9 else R[2*i] + R[2*i-2] for i, d in enumerate(map(int, str(n).zfill(4)))) </pre>

adidassg11 on Feb. 24, 2017, 6:04 a.m.
@veky I see that you have a very pythonic structure here but I think with such a big lambda, you're better off just writing this in a more explicit way. I think this solution might be going against several items from PEP20.

veky on Feb. 24, 2017, 6:08 a.m.
I think you haven't read my comment carefully. Try to read it again. See that it has two paragraphs. First is talking about my solution (published solution of this mission, by me), and the other is talking about trivial condensing of @nathan.l.cook's solution.

oduvan on Sept. 29, 2016, 1:25 p.m.
you don't need "0" in line 11 Right?

Kostas_Mouratidis on Dec. 27, 2016, 3:10 p.m.
I guess I'm late, but yes, it is not needed. It could be (place*2)

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