Python Forum

Hello All,

I am trying to convert Roman number to Integer (III-->3) and to do that I need to compare characters one by one in a dictionary. How do I not get this error?

If this was a string I can do where S[i]=s[i+1], Tried to do same in the dictionary but it is throwing me an error.


def prit(num,count):
i=0
while(i<len(num)):
if(len(num)==1):
count = count + dict1[num[0]]
if(len(num)==0):
print(count)
exit()
else:
if(dict1[num[i]]>=dict1[num[i+1]]):
count = count + dict1[num[i]]
i=i+1
else:
count = dict1[num[i+1]]-dict1[num[i]]+count
i=i+2

return count
num="LVIII"
count=0
dict1 = {"I": 1,
"V": 5,
"X": 10,
"L": 50,
"C": 100,
"D": 500,
"M": 1000

}
count=prit(num,count)
print(count)

Please use proper tags when posting.

---

Here is a working example

#! /usr/bin/env python3

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

def convert(rn):
    converted = []
    for val in rn:
        if val in roman.keys():
            converted.append(roman[val])
    return sum(converted)
print(convert('XVI'))

Output:
16

Gonna go ahead and add one to convert to roman numerals. This one took a while to figure out. Using the same dict as above.

def to_roman(num):
    keys = []
    values = []
    for key in roman.keys():
        keys.append(key)

    for value in roman.values():
        values.append(value)
    keys.reverse()
    values.reverse()

    rom = ''
    i = 0
    while num > 0:
        for _ in range(num // values[i]):
            rom += keys[i]
            num -= values[i]
        i += 1
    return rom

print(to_roman(326))

Output:
CCCXXVI