Excel files can contain up to 16,384 (2¹⁴) columns. The first 26 columns are labeled "A", "B", "C", and so on. After that it is "AA", "AB", "AC", ..., "BA", "BB", "BC", ..., and so on, but two-letter labels only support an additional 26²=676 columns. So eventually we see "AAA", "AAB", "AAC", and so on, to a max of "XFD".

I'd like to write a Python function that converts a column offset/index to a column label.

For the first 26 columns this is trivial.

>>> offset = 0
>>> chr(offset   65)
'A'

But how do I generalize this to support all valid inputs and outputs?

I tried adapting this code and converting the offsets to numbers in base 26, and then using chr to convert each place value to a letter. But I couldn't get it to work as intended.

def numberToBase(n, b):
    if n == 0:
        return [0]
    digits = []
    while n:
        digits.append(int(n % b))
        n //= b
    return digits[::-1]

CodePudding user response：

Here is my version using recursion:

def column_offset_to_column_name(index):
    if index < 0:
        return ""
    quotient, remainder = divmod(index, 26)
    return column_offset_to_column_name(quotient - 1)   chr(remainder   65)