How can I generate a list of possible 'words' when all I know is the number of letters of each word in Python?

Question

I know this is probably a dumb question and I am missing something really simple, but I can’t for the life of me figure out where I am going wrong… I am ultimately trying to generate a list of all possible letter combinations with a string of a given length. I know some of these letter combinations wont be pronounceable, but I am going to call them ‘words’ nonetheless for simplicity. For example, if I know my string is one letter long, I want to generate a list of letters, "A" though "Z", 26 elements long. If I know my string is two letters long, I will need a list of "words" from "AA" to "ZZ", 676 elements long. The rub comes where I do not know the number of letters ahead of time.

If I know my ‘word’ will only be one letter, then I can do this:

letters = ["A", "B", "C", ... "X", "Y", "Z"]
words = []
for x in range(26):
    words.append(letters[x])
print(words)

If I know my ‘word’ will be two letters long, I can do this:

letters = ["A", "B", "C", ... "X", "Y", "Z"]
words = []
for x in range(26):
    for y in range(26):
        words.append(letters[x] + letters[y])
print(words)

What I can’t for the life of me figure out is how to do this when I don’t know ahead of time how many letters my word will have. I basically want a formula where I give it the number of letters, and it gives me a list of all the possible words, that number of letters long. Something to the effect of:

def possible_words(word_length):
    list_of_words = []
    number_of_words = 26 ** word_length
    for x in range(number_of_words):
        '''generate the new word here'''
        list_of_words.append(new_word)
    return list_of_words

Where am I going wrong? What am I missing? I feel like I am so close, I know this has to be a simple problem, but I have been racking my brain for a few hours now and can’t figure it out. I feel like the solution lies in something involving recursion? And I think I maybe can’t get the numbers to line up with the words because of a combination of zero-indexing and the fact that a ‘zero letter’ doesn’t exist? I don’t know, the more I think the more confused I get… Please help! Thanks in advance!

EDIT: Thanks to those who responded and specifically to njp and Thierry Lathuille who directed me towards itertools.product! The solutions was even more pythonic than I could have hoped for! Below is the code I ended up using, in case anyone else comes across the same issue:

import itertools

alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
word_length = 2    # The 2 is just for testing, actual value will be determined programatically...
letter_tuples = itertools.product(alphabet, repeat=word_length)
words = ["".join(letter_tuple) for letter_tuple in letter_tuples]
print(words)

Asked By: Valiant

||

Source

Answer 1

this is a standard permutations problem.

what you want is:
itertools.permutations

Answered By: Remzi

Answer 2

You can get what you want using itertools.product, specifically:

import itertools as it

list(it.product(letters, repeat=3))

 ('A', 'A', 'B'),
 ('A', 'A', 'C'),
 ('A', 'A', 'D'),
 ('A', 'A', 'E'),
 ('A', 'A', 'F'),
 ...

it.product works exactly as nested for-loops.

Answered By: njp

Answer 3

I created a bit of code. I think this is what you mean. You change the variable on how many times each letter is shown. I hope this helps.

word_length = 1
list_of_words = []
letters = ["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"]
letter_on = 0
count = 0
for x in range(word_length*len(letters)):
  if letter_on != 27:
    if count != word_length:
      list_of_words.append(letters[letter_on])
      count+=1
    else:
      count=0
      letter_on+=1
  else:
    break

print(list_of_words)

Answered By: OliDev

How can I generate a list of possible 'words' when all I know is the number of letters of each word in Python?

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