Objective-C或Swift中的Jaro Winkler距离

- (CGFloat)jaroWinklerDistance:(NSString *)str1 withString:(NSString *)str2 {
    NSInteger len1 = str1.length;
    NSInteger len2 = str2.length;
    
    if (len1 == 0 && len2 == 0) {
        return 1.0;
    }
    
    NSInteger matchDistance = MAX(len1, len2) / 2 - 1;
    NSMutableCharacterSet *commonSet = [NSMutableCharacterSet new];
    
    NSMutableString *commonChars1 = [NSMutableString new];
    NSMutableString *commonChars2 = [NSMutableString new];
    
    NSInteger matchingCharacters = 0;
    
    for (NSInteger i = 0; i < len1; i++) {
        NSInteger start = MAX(0, i - matchDistance);
        NSInteger end = MIN(i + matchDistance + 1, len2);
        
        NSRange range = [str2 rangeOfCharacterFromSet:[NSCharacterSet characterSetWithCharactersInString:[str1 substringWithRange:NSMakeRange(i, 1)]] options:NSLiteralSearch range:NSMakeRange(start, end - start)];
        
        if (range.location != NSNotFound) {
            [commonChars1 appendString:[str1 substringWithRange:NSMakeRange(i, 1)]];
            [commonChars2 appendString:[str2 substringWithRange:range]];
            [commonSet addCharactersInString:[str1 substringWithRange:NSMakeRange(i, 1)]];
            matchingCharacters++;
        }
    }
    
    if (matchingCharacters == 0) {
        return 0.0;
    }
    
    NSInteger transpositions = 0;
    
    for (NSInteger i = 0; i < commonChars1.length; i++) {
        if (![commonChars1 characterAtIndex:i] == [commonChars2 characterAtIndex:i]) {
            transpositions++;
        }
    }
    
    transpositions /= 2;
    
    CGFloat jaroDistance = (CGFloat)matchingCharacters / len1;
    
    CGFloat prefixScale = 0.1;
    NSInteger prefixLength = MIN(4, MIN(len1, len2));
    
    CGFloat commonPrefixLength = 0;
    
    for (NSInteger i = 0; i < prefixLength; i++) {
        if ([str1 characterAtIndex:i] == [str2 characterAtIndex:i]) {
            commonPrefixLength++;
        } else {
            break;
        }
    }
    
    return jaroDistance + prefixScale * (CGFloat)commonPrefixLength * (1.0 - jaroDistance);
}

func jaroWinklerDistance(str1: String, str2: String) -> CGFloat {
    let len1 = str1.count
    let len2 = str2.count
    
    if len1 == 0 && len2 == 0 {
        return 1.0
    }
    
    let matchDistance = max(len1, len2) / 2 - 1
    let commonSet = NSMutableCharacterSet()
    
    var commonChars1 = ""
    var commonChars2 = ""
    
    var matchingCharacters = 0
    
    for i in 0..<len1 {
        let start = max(0, i - matchDistance)
        let end = min(i + matchDistance + 1, len2)
        
        if let range = str2.rangeOfCharacter(from: CharacterSet(charactersIn: String(str1[str1.index(str1.startIndex, offsetBy: i)]))), options: .literal, range: Range(NSRange(location: start, length: end - start), in: str2)) {
            commonChars1 += String(str1[str1.index(str1.startIndex, offsetBy: i)])
            commonChars2 += String(str2[range])
            commonSet.addCharacters(in: String(str1[str1.index(str1.startIndex, offsetBy: i)]))
            matchingCharacters += 1
        }
    }
    
    if matchingCharacters == 0 {
        return 0.0
    }
    
    var transpositions = 0
    
    for i in 0..<commonChars1.count {
        if Array(commonChars1)[i] != Array(commonChars2)[i] {
            transpositions += 1
        }
    }
    
    transpositions /= 2
    
    let jaroDistance = CGFloat(matchingCharacters) / CGFloat(len1)
    
    let prefixScale: CGFloat = 0.1
    let prefixLength = min(4, min(len1, len2))
    
    var commonPrefixLength = 0
    
    for i in 0..<prefixLength {
        if Array(str1)[i] == Array(str2)[i] {
            commonPrefixLength += 1
        } else {
            break
        }
    }
    
    return jaroDistance + prefixScale * CGFloat(commonPrefixLength) * (1.0 - jaroDistance)
}