characterSimilarity method

double characterSimilarity(String other)

Returns the similarity between the collection of letters of this String and other on a scale of 0.0 to 1.0.

Compares the characters in this and other by splitting each string into a set of its unique characters and finding the intersection between the two sets of characters.

• Returns 1.0 if the two Strings are the same (this.trim().toLowerCase() == other.trim().toLowerCase()).
• Returns 1.0 if the character set for this and the intersection have the same length AND this and other are the same length.
• Returns 0.0 if the intersection is empty (no shared characters).
• Returns the intersection length divided by the average length of the two character sets multiplied by the length similarity.

The String and other are converted to lower-case and trimmed for the comparison.

Not case-sensitive.

Implementation

double characterSimilarity(String other) {
  final term = trim().toLowerCase();
  other = other.trim().toLowerCase();
  if (term == other) return 1.0;
  final thisChars = term.split('').toSet();
  final otherChars = other.trim().toLowerCase().split('').toSet();
  final intersection = thisChars.intersection(otherChars);
  final lengthSimilarity = term.lengthSimilarity(other);
  if (intersection.length == thisChars.length &&
      term.lengthDistance(other) == 0) {
    return 1.0;
  }
  return (intersection.length * 2 / (thisChars.length + otherChars.length)) *
      lengthSimilarity;
}