How can I optimize this Python code to generate all words with word-distance 1?

Question

Profiling shows this is the slowest segment of my code for a little word game I wrote:

def distance(word1, word2):
    difference = 0
    for i in range(len(word         


        

Answer 1

First thing to occur to me:

from operator import ne

def distance(word1, word2):
    return sum(map(ne, word1, word2))

which has a decent chance of going faster than other functions people have posted, because it has no interpreted loops, just calls to Python primitives. And it's short enough that you could reasonably inline it into the caller.

For your higher-level problem, I'd look into the data structures developed for similarity search in metric spaces, e.g. this paper or this book, neither of which I've read (they came up in a search for a paper I have read but can't remember).