Groovy string match 90% (ignore letter casing) - grails

Question

I need to write a Groovy function to check if two given strings match at least 90%. I just wanted to know if anyone knew of an already existent such utility method that I could use in a Grails project. I haven't really written the method yet but ideally this is how it would work:
def doStringsMatch(String str1, String str2) {
if (str1 and str2 match at least 90% or
str1 appears in str2 somewhere or
str2 appears in str1 somewhere)
return true
else
return false
}
Thanks

Answer 1

This is a groovy implementation of Levenshtein distance, basically it returns a percentage of how similar the two strings appear to be. 0 means they are completely different and 1 means they are the exact same. This implementation is case insensitive.
private double similarity(String s1, String s2) {
if (s1.length() < s2.length()) { // s1 should always be bigger
String swap = s1; s1 = s2; s2 = swap;
}
int bigLen = s1.length();
if (bigLen == 0) { return 1.0; /* both strings are zero length */ }
return (bigLen - computeEditDistance(s1, s2)) / (double) bigLen;
}
private int computeEditDistance(String s1, String s2) {
s1 = s1.toLowerCase();
s2 = s2.toLowerCase();
int[] costs = new int[s2.length() + 1];
for (int i = 0; i <= s1.length(); i++) {
int lastValue = i;
for (int j = 0; j <= s2.length(); j++) {
if (i == 0)
costs[j] = j;
else {
if (j > 0) {
int newValue = costs[j - 1];
if (s1.charAt(i - 1) != s2.charAt(j - 1))
newValue = Math.min(Math.min(newValue, lastValue),
costs[j]) + 1;
costs[j - 1] = lastValue;
lastValue = newValue;
}
}
}
if (i > 0)
costs[s2.length()] = lastValue;
}
return costs[s2.length()];
}