If you want to convert between Excel Column (e.g. 'BF') and which number it is and back

ExcelColumns.py

import string
letter = string.ascii_uppercase
def num2excelcolumn(n):
    '''
    letter for the corresponding column
    '''
    if not isinstance(n, int):
        raise Exception('Spalte kann nur ganze Zahl sein')
    if n<27:
        return letter[n-1]
    elif n<703:
        return letter[(n-1)/26-1] + letter[n%26-1]
    elif n<17603:
        return letter[(n-1)/(26*26)-1] + letter[(n-26*26-1)/26-1] + letter[n%26-1]
    else:
        raise Exception('Sorry, nur 3 Buchstaben!')
    
def excelcolumn2num(s):
    '''
    number for the corresponding column letters
    '''
    for i in range(17603): # just bruteforce it
        if num2excelcolumn(i)==s:
            return i
        
def e2i(s):
    '''
    Python index for the corresponding column letters
    '''
    for i in range(17603): # just bruteforce it
        if num2excelcolumn(i)==s:
            return i-1

Usage:

In [148]: num2excelcolumn(442)
Out[148]: 'PZ'
In [150]: excelcolumn2num('HZ')
Out[150]: 234