t9.py

#!/usr/bin/python3

def recursive_t9(numbers, letter_map):
    if len(str(numbers)) == 1:
        return letter_map[int(numbers)]
    elif len(str(numbers)) == 0:
        return []

    other_options = recursive_t9(str(numbers)[1:], letter_map)

    words = []
    for option in letter_map[int(str(numbers)[0])]:
        for other_option in other_options:
            words.append(option+other_option)
    return words

def t9_predictor(numbers, valid_words):
    letter_map = [[],[],['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']]
    possible_words = recursive_t9(numbers, letter_map)
    return list(set(possible_words) & set(valid_words))


if __name__ == "__main__":
    with open('/usr/share/dict/words') as f:
        valid_words = f.read().splitlines()
        while True:
            numbers = input("Enter numbers: ")
            print(t9_predictor(numbers, valid_words))