A function for calculating the Levensthein edit distance between columns with Jython in Open Refine

levenshtein.py

def call_counter(func):
    def helper(*args, **kwargs):
        helper.calls += 1
        return func(*args, **kwargs)
    helper.calls = 0
    helper.__name__= func.__name__
    return helper
memo = {}
@call_counter
def levenshtein(s, t):
    if s == "":
        return len(t)
    if t == "":
        return len(s)
    cost = 0 if s[-1] == t[-1] else 1
       
    i1 = (s[:-1], t)
    if not i1 in memo:
        memo[i1] = levenshtein(*i1)
    i2 = (s, t[:-1])
    if not i2 in memo:
        memo[i2] = levenshtein(*i2)
    i3 = (s[:-1], t[:-1])
    if not i3 in memo:
        memo[i3] = levenshtein(*i3)
    res = min([memo[i1]+1, memo[i2]+1, memo[i3]+cost])
    return res

def call_counter(func):
    def helper(*args, **kwargs):
        helper.calls += 1
        return func(*args, **kwargs)
    helper.calls = 0
    helper.__name__= func.__name__
    return helper
memo = {}
@call_counter
def levenshtein(s, t):
    if s == "":
        return len(t)
    if t == "":
        return len(s)
    cost = 0 if s[-1] == t[-1] else 1
       
    i1 = (s[:-1], t)
    if not i1 in memo:
        memo[i1] = levenshtein(*i1)
    i2 = (s, t[:-1])
    if not i2 in memo:
        memo[i2] = levenshtein(*i2)
    i3 = (s[:-1], t[:-1])
    if not i3 in memo:
        memo[i3] = levenshtein(*i3)
    res = min([memo[i1]+1, memo[i2]+1, memo[i3]+cost])
    return res

return levenshtein(value, cells['other column']['value'])