How to a sort list in the given alphabetical order using python?

Question

Inputs:

Alpha = ['d', 'c', 'a', 'b']
words = ['dda', 'bdb', 'adc', 'cdd']

How do I sort words in the order of Alpha to get the following result?

words = ['dda', 'cdd', 'adc', 'bdb']

Could you please me on how to do this?

Here I am trying to sort a list but not the dictionary keys

Answer 1

This will sort the words lexicographically based on your order specified in alpha, by making a list of indices for each word (which Python then compares lexicographically)

def sort_key(w):
    return [alpha.index(ch) for ch in w]

words.sort(key=sort_key)

There are likely to be more efficient solutions that store the key in a hash (as in the answer to this question).

An alternative would be to turn your alpha into a string.translate translation table.

ascii_characters = ''.join(chr(i) for i in range(256))
translation = string.maketrans(''.join(alpha), ascii_characters[:len(alpha)])
words.sort(key=lambda w: w.translate(translation))

An advantage of this way is that you can put the translations into a dictionary for (possibly) greater speed.

order = {w: w.translate(translation) for w in words}
words.sort(key=lambda w: order[w]))