Compare two strings by ignoring certain characters

string str1 = "ABC-EFG";
string str2 = "ABC*EFG";

[a-zA-z]{3}.[a-zA-z]{3}

def dist(s1, s2):
    d = {}
    lenstr1 = len(s1)
    lenstr2 = len(s2)
    for i in xrange(-1,lenstr1+1):
        d[(i,-1)] = i+1
    for j in xrange(-1,lenstr2+1):
        d[(-1,j)] = j+1

    for i in xrange(0,lenstr1):
        for j in xrange(0,lenstr2):
            if s1[i] == s2[j]:
                cost = 0
            else:
                cost = 1
            d[(i,j)] = min(
                d[(i-1,j)] + 1, # deletion
                d[(i,j-1)] + 1, # insertion
                d[(i-1,j-1)] + cost, # substitution
                )
            if i>1 and j>1 and s1[i]==s2[j-1] and s1[i-1] == s2[j]:
                d[(i,j)] = min (d[(i,j)], d[i-2,j-2] + cost) # transposition

    return d[lenstr1-1,lenstr2-1]

String.Compare(str1, str2, CultureInfo.InvariantCulture, CompareOptions.IgnoreSymbols)