In [1]:

    

mapping = {'I': 1,
           'V': 5,
           'X': 10,
           'L': 50,
           'C': 100,
           'D': 500,
           'M': 1000}


    

In [26]:

    

def roman_to_arabic(string):
    out = 0
    position = 0
    
    while position < len(string):
        val = mapping[string[position]]
        if position == len(string)-1:
            #-- goto ADD
            out += val
            position += 1
        else:
            nextval = mapping[string[position+1]]

            if val == 1 and (nextval in [5, 10]):
                #-- goto subtract
                out += (nextval - val)
                position += 2
            elif val == 10 and (nextval in [50, 100]):
                out += (nextval - val)
                position += 2
            elif val == 100 and (nextval in [500, 1000]):
                out += (nextval - val)
                position += 2
            else:
                out += val
                position += 1
            
    return out


    

In [ ]:

    




    

In [39]:

    

roman_to_arabic('MDCCCCVIIII')


    

    




0 11
1 11
2 11
3 11
4 11
5 11
6 11
7 11
8 11
9 11
10 11






    
Out[39]:





1909

In [ ]: