calc_excel_column_number.py

from string import letters

def calc_excel_column_number(string):
    """
    Return number representing the column index in MS excel

    A is the first column - return 1
    B is the second column - return 2
    ...
    Z is the 26th column - return 26
    AA is the 27th column - return 27
    ...
    etc.
    """
    result = 0
    for index, char in enumerate(reversed(string), 0):
        result += (letters.index(char.lower()) + 1) * 26 ** index
    return result