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

from itertools import izip

def is_neighbors(word1,word2):
    different = False
    for c1,c2 in izip(word1,word2):
        if c1 != c2:
            if different:
                return False
            different = True
    return different

Or maybe in-lining the izip code:

def is_neighbors(word1,word2):
    different = False
    next1 = iter(word1).next
    next2 = iter(word2).next
    try:
        while 1:
            if next1() != next2():
                if different:
                    return False
                different = True
    except StopIteration:
        pass
    return different

And a rewritten getchildren:

def iterchildren(word, wordlist):
    return ( w for w in wordlist if is_neighbors(word, w) )

• izip(a,b) returns an iterator over pairs of values from a and b.
• zip(a,b) returns a list of pairs from a and b.