Tukukkk

I want to create alphabetically ascending names like the column names in excel. That is I want to have smth. like a,b,c,...,z,aa,ab,...az,...zz,aaa,aab,....

I have tried:

for i in range(1000):

    mod = int(i%26)

    div = int(i/26)

    print(string.ascii_lowercase[div]+string.ascii_lowercase[mod])

Which works until zz but than fails because it runs out of index

aa

ab

ac

ad

ae

af

ag

ah

ai

aj

ak

al

.

.

.

zz

IndexError

You could make use of itertools.product():

from itertools import product

from string import ascii_lowercase



for i in range(1, 4):

    for x in product(ascii_lowercase, repeat=i):

        print(''.join(x))

First, you want all letters, then all pairs, then all triplets, etc. This is why we first need to iterate through all the string lengths you want (for i in range(...)).

Then, we need all possible associations with the i letters, so we can use product(ascii_lowercase) which is equivalent to a nested for loop repeated i times.

This will generate the tuples of size i required, finally just join() them to obtain a string.

To continuously generate names without limit, replace the for loop with while:

def generate():

    i = 0

    while True:

        i += 1

        for x in product(ascii_lowercase, repeat=i):

            yield ''.join(x)



generator = generate()

next(generator)  # 'a'

next(generator)  # 'b'

...

For a general solution we can use a generator and islice from itertools:

import string

from itertools import islice

def generate():

    base = ['']

    while True:

        next_base = 

        for b in base:

            for i in range(26):

                next_base.append(b + string.ascii_lowercase[i])

                yield next_base[-1]

        base = next_base



print('n'.join(islice(generate(), 1000)))

And the output:

a

b

c

...

z

aa

ab

...

zz

aaa

aab

...

And you can use islice to take as many strings as you need.

Try:

>>import string

>>string.ascii_lowercase

'abcdefghijklmnopqrstuvwxyz'

>>len(string.ascii_lowercase)

26

When your index in below line exceed 26 it raise exception

div = int(i/26)

, becouse of ascii_lowercase length:

But you can:

for i in range(26*26):  # <--- 26 is string.ascii_lowercase

    mod = int(i%26)

    div = int(i/26)

    print(string.ascii_lowercase[div]+string.ascii_lowercase[mod])

EDIT:

or you can use:

import string



n = 4  # number of chars

small_limit = len(string.ascii_lowercase)

limit = small_limit ** n

i = 0

while i < limit:

    s = ''

    for c in range(n):

        index = int(i/(small_limit**c))%small_limit

        s += string.ascii_lowercase[index]

    print(s)

    i += 1

You can use:

from string import ascii_lowercase

l = list(ascii_lowercase) + [letter1+letter2 for letter1 in ascii_lowercase for letter2 in ascii_lowercase]+ [letter1+letter2+letter3 for letter1 in ascii_lowercase for letter2 in ascii_lowercase for letter3 in ascii_lowercase]

There's an answer to this question provided on Code Review SE

A slight modification to the answer in the link gives the following which works for an arbitrary number of iterations.

def increment_char(c):

    return chr(ord(c) + 1) if c != 'z' else 'a' 



def increment_str(s):

    lpart = s.rstrip('z')

    num_replacements = len(s) - len(lpart)

    new_s = lpart[:-1] + increment_char(lpart[-1]) if lpart else 'a' 

    new_s += 'a' * num_replacements

    return new_s



s = ''

for _ in range(1000):

    s = increment_str(s)

    print(s)