elegant way to match two wildcarded strings

Question

I'm OCRing some text from two different sources. They can each make mistakes in different places, where they won't recognize a letter/group of letters. If they don't recognize something, it's replaced with a ?. For example, if the word is Roflcopter, one source might return Ro?copter, while another, Roflcop?er. I'd like a function that returns whether two matches might be equivalent, allowing for multiple ?s. Example:

match("Ro?copter", "Roflcop?er") --> True
match("Ro?copter", "Roflcopter") --> True
match("Roflcopter", "Roflcop?er") --> True
match("Ro?co?er", "Roflcop?er") --> True

So far I can match one OCR with a perfect one by using regular expressions:

>>> def match(tn1, tn2):
    tn1re = tn1.replace("?", ".{0,4}")
    tn2re = tn2.replace("?", ".{0,4}")

    return bool(re.match(tn1re, tn2) or re.match(tn2re, tn1))

>>> match("Roflcopter", "Roflcop?er")
True
>>> match("R??lcopter", "Roflcopter")
True

But this doesn't work when they both have ?s in different places:

>>> match("R??lcopter", "Roflcop?er")
False

Answer 1

Well, as long as one ? corresponds to one character, then I can suggest a performant and a compact enough method.

def match(str1, str2):
    if len(str1) != len(str2): return False
    for index, ch1 in enumerate(str1):
        ch2 = str2[index]
        if ch1 == '?' or ch2 == '?': continue
        if ch1 != ch2: return False
    return True

---

>>> ================================ RESTART ================================
>>> 
>>> match("Roflcopter", "Roflcop?er")
True
>>> match("R??lcopter", "Roflcopter")
True
>>> 
>>> match("R??lcopter", "Roflcop?er")
True
>>> 

Edit: Part B), brain-fart free now.

def sets_match(set1, set2):
    return any(match(str1, str2) for str1 in set1 for str2 in set2)

---

>>> ================================ RESTART ================================
>>> 
>>> s1 = set(['a?', 'fg'])
>>> s2 = set(['?x'])
>>> sets_match(s1, s2) # a? = x?
True
>>> 

Answer 2

Thanks to Hamish Grubijan for this idea. Every ? in my ocr'd names can be anywhere from 0 to 3 letters. What I do is expand each string to a list of possible expansions:

>>> list(expQuestions("?flcopt?"))
['flcopt', 'flcopt@', 'flcopt@@', 'flcopt@@@', '@flcopt', '@flcopt@', '@flcopt@@', '@flcopt@@@', '@@flcopt', '@@flcopt@', '@@flcopt@@', '@@flcopt@@@', '@@@flcopt', '@@@flcopt@', '@@@flcopt@@', '@@@flcopt@@@']

then I expand both and use his matching function, which I called matchats:

def matchOCR(l, r):
    for expl in expQuestions(l):
        for expr in expQuestions(r):
            if matchats(expl, expr):
                return True
    return False

Works as desired:

>>> matchOCR("Ro?co?er", "?flcopt?")
True
>>> matchOCR("Ro?co?er", "?flcopt?z")
False
>>> matchOCR("Ro?co?er", "?flc?pt?")
True
>>> matchOCR("Ro?co?e?", "?flc?pt?")
True

---

The matching function:

def matchats(l, r):
    """Match two strings with @ representing exactly 1 char"""
    if len(l) != len(r): return False
    for i, c1 in enumerate(l):
        c2 = r[i]
        if c1 == "@" or c2 == "@": continue
        if c1 != c2: return False
    return True

and the expanding function, where cartesian_product does just that:

def expQuestions(s):
    """For OCR w/ a questionmark in them, expand questions with
    @s for all possibilities"""
    numqs = s.count("?")

    blah = list(s)
    for expqs in cartesian_product([(0,1,2,3)]*numqs):
        newblah = blah[:]
        qi = 0
        for i,c in enumerate(newblah):
            if newblah[i] == '?':
                newblah[i] = '@'*expqs[qi]
                qi += 1
        yield "".join(newblah)