lev.py

# -*- coding: utf-8 -*-

import sys


def levenshtein(a, b):
    """ Calculates the Levenshtein distance between a and b.
    from http://hetland.org/coding/python/levenshtein.py

    For other implementations, see
    http://en.wikibooks.org/wiki/Algorithm_Implementation/Strings/Levenshtein_distance
    """
    n, m = len(a), len(b)
    if n > m:
        a, b = b, a
        n, m = m, n
    current = range(n + 1)
    for i in range(1, m + 1):
        previous, current = current, [i] + [0] * n
        for j in range(1, n + 1):
            add, delete = previous[j] + 1, current[j - 1] + 1
            change = previous[j - 1]
            if a[j - 1] != b[i - 1]:
                change = change + 1
            current[j] = min(add, delete, change)
    return current[n]


if len(sys.argv) < 3:
    print "dos argumentos"
    exit(1)

print levenshtein(sys.argv[1], sys.argv[2])