jaroSimilarity function

double jaroSimilarity(String s1, String s2)

Calculates the Jaro similarity between two strings

Implementation

double jaroSimilarity(String s1, String s2) {
  if (s1 == s2) return 1.0;
  if (s1.isEmpty || s2.isEmpty) return 0.0;
  if (s1.length == 1 && s2.length == 1) return s1 == s2 ? 1.0 : 0.0;

  final matchWindow = (max(s1.length, s2.length) ~/ 2) - 1;
  final matches1 = List<bool>.filled(s1.length, false);
  final matches2 = List<bool>.filled(s2.length, false);
  var matches = 0;
  var transpositions = 0;

  // Find matches
  for (var i = 0; i < s1.length; i++) {
    final start = max(0, i - matchWindow);
    final end = min(i + matchWindow + 1, s2.length);
    for (var j = start; j < end; j++) {
      if (!matches2[j] && s1[i] == s2[j]) {
        matches1[i] = true;
        matches2[j] = true;
        matches++;
        break;
      }
    }
  }

  if (matches == 0) return 0.0;

  // Count transpositions
  var k = 0;
  for (var i = 0; i < s1.length; i++) {
    if (matches1[i]) {
      while (!matches2[k]) {
        k++;
      }
      if (s1[i] != s2[k]) transpositions++;
      k++;
    }
  }

  transpositions = transpositions ~/ 2;

  return (matches / s1.length +
          matches / s2.length +
          (matches - transpositions) / matches) /
      3.0;
}