Python Program to Generate alphabetic list in lexical order like column names in excel

Question

How to Generate alphabetic list of given length in lexical order same as column header in MS excel.

['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'X', 'Y', 'Z', 'AA', 'AB', 'AC', 'AD', 'AE' . . . ]

If length of list is given 28 then ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'X', 'Y', 'Z', 'AA', 'AB']

If length of list is given 35 then ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'X', 'Y', 'Z', 'AA', 'AB', 'AC', 'AD', 'AE', 'AF', 'AG', 'AH', 'AI']

score 2 · Answer 1 · answered Sep 08 '21 at 06:50

2

You could try this list comprehension:

>>> import string
>>> x = 35
>>> [string.ascii_uppercase[i] if i < 26 else string.ascii_uppercase[i // 26 - 1] + string.ascii_uppercase[i % 26] for i in range(x)]
['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'AA', 'AB', 'AC', 'AD', 'AE', 'AF', 'AG', 'AH', 'AI']
>>>

answered Sep 08 '21 at 06:50

U13-Forward

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1

OP doesn't say the upper limit for these is two characters; they say "given length"... – AKX Sep 08 '21 at 06:52
1

this code is wrong and don't work for input x > 26*26 and your code didn't work for 'AAA' or 'BBB' or 'AAAA' or ... this hasty solution – I'mahdi Sep 08 '21 at 06:57

JvdV · Answer 2 · 2021-09-08T07:16:55.383

1

Maybe the following would work:

from openpyxl.utils.cell import get_column_letter
x = 35
lst = [get_column_letter(i + 1) for i in range(x)]
print(lst)

Prints:

['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'AA', 'AB', 'AC', 'AD', 'AE', 'AF', 'AG', 'AH', 'AI']

edited Sep 08 '21 at 07:16

answered Sep 08 '21 at 07:05

JvdV

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Péter Leéh · Answer 3 · 2021-09-08T07:18:47.163

Using itertools.product with all the letters gives you the combinations you want:

>>> list(product(ascii_uppercase, repeat=3))
[('A', 'A', 'A'),
 ('A', 'A', 'B'),
 ('A', 'A', 'C'),
 ('A', 'A', 'D'),
 ('A', 'A', 'E'),
 ('A', 'A', 'F'),
 ...
 ('Z', 'Z', 'Z')]

We need to modify the repeat if we're out items for a given repeat. Making it a generator:

from string import ascii_uppercase

def gen_columns():
    n = 1
    while True:
        # yield the items
        yield from [''.join(group) for group in product(ascii_uppercase, repeat=n)]
        # we're out of all combinations, add one more letter.
        n += 1

To take arbitrary number of elements from this generator, use itertools.islice:

>>> list(islice(gen_columns(), 35))
['A',
 'B',
 'C',
 'D',
 'E',
 'F',
 'G',
 'H',
 'I',
 'J',
 'K',
 'L',
 'M',
 'N',
 'O',
 'P',
 'Q',
 'R',
 'S',
 'T',
 'U',
 'V',
 'W',
 'X',
 'Y',
 'Z',
 'AA',
 'AB',
 'AC',
 'AD',
 'AE',
 'AF',
 'AG',
 'AH',
 'AI']

Credit: Repeating letters like excel columns?

Python Program to Generate alphabetic list in lexical order like column names in excel

3 Answers3