# Class JaroWinklerSimilarity

java.lang.Object
org.apache.commons.text.similarity.JaroWinklerSimilarity

All Implemented Interfaces:
  `BiFunction<CharSequence, CharSequence, Double>, ObjectSimilarityScore<CharSequence, Double>, SimilarityScore<Double>`

public class JaroWinklerSimilarity extends Object implements SimilarityScore<Double>
A similarity algorithm indicating the percentage of matched characters between two character sequences.

The Jaro measure is the weighted sum of percentage of matched characters from each file and transposed characters. Winkler increased this measure for matching initial characters.

This implementation is based on the Jaro Winkler similarity algorithm from https://en.wikipedia.org/wiki/Jaro%E2%80%93Winkler_distance.

This code has been adapted from Apache Commons Lang 3.3.

Since:
  1.7

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `JaroWinklerSimilarity()`
  Creates a new instance.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `Double`
  `apply(CharSequence left, CharSequence right)`
  Computes the Jaro Winkler Similarity between two character sequences.
  `<E> Double`
  `apply(SimilarityInput<E> left, SimilarityInput<E> right)`
  Computes the Jaro Winkler Similarity between two character sequences.
  `protected static int[]`
  `matches(CharSequence first, CharSequence second)`
  Computes the Jaro-Winkler string matches, half transpositions, prefix array.
  `protected static <E> int[]`
  `matches(SimilarityInput<E> first, SimilarityInput<E> second)`
  Computes the Jaro-Winkler string matches, half transpositions, prefix array.

  ### Methods inherited from class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

  ### Methods inherited from interface BiFunction

  `andThen`

- ## Constructor Details

  - ### JaroWinklerSimilarity

    public JaroWinklerSimilarity()
    Creates a new instance.

- ## Method Details

  - ### matches

    protected static int[] matches(CharSequence first, CharSequence second)
    Computes the Jaro-Winkler string matches, half transpositions, prefix array.
    Parameters:
      `first` - the first input to be matched.
      `second` - the second input to be matched.
    Returns:
      mtp array containing: matches, half transpositions, and prefix.

  - ### matches

    protected static <E> int[] matches(SimilarityInput<E> first, SimilarityInput<E> second)
    Computes the Jaro-Winkler string matches, half transpositions, prefix array.
    Type Parameters:
      `E` - The type of similarity score unit.
    Parameters:
      `first` - the first input to be matched.
      `second` - the second input to be matched.
    Returns:
      mtp array containing: matches, half transpositions, and prefix.
    Since:
      1.13.0

  - ### apply

    public Double apply(CharSequence left, CharSequence right)
    Computes the Jaro Winkler Similarity between two character sequences.

        sim.apply(null, null)          = Throws IllegalArgumentException
        sim.apply("foo", null)         = Throws IllegalArgumentException
        sim.apply(null, "foo")         = Throws IllegalArgumentException
        sim.apply("", "")              = 1.0
        sim.apply("foo", "foo")        = 1.0
        sim.apply("foo", "foo ")       = 0.94
        sim.apply("foo", "foo  ")      = 0.91
        sim.apply("foo", " foo ")      = 0.87
        sim.apply("foo", "  foo")      = 0.51
        sim.apply("", "a")             = 0.0
        sim.apply("aaapppp", "")       = 0.0
        sim.apply("frog", "fog")       = 0.93
        sim.apply("fly", "ant")        = 0.0
        sim.apply("elephant", "hippo") = 0.44
        sim.apply("hippo", "elephant") = 0.44
        sim.apply("hippo", "zzzzzzzz") = 0.0
        sim.apply("hello", "hallo")    = 0.88
        sim.apply("ABC Corporation", "ABC Corp") = 0.91
        sim.apply("D N H Enterprises Inc", "D & H Enterprises, Inc.") = 0.95
        sim.apply("My Gym Children's Fitness Center", "My Gym. Childrens Fitness") = 0.92
        sim.apply("PENNSYLVANIA", "PENNCISYLVNIA") = 0.88

    Specified by:
      `apply` in interface `BiFunction<CharSequence, CharSequence, Double>`
    Specified by:
      `apply` in interface `ObjectSimilarityScore<CharSequence, Double>`
    Specified by:
      `apply` in interface `SimilarityScore<Double>`
    Parameters:
      `left` - the first input, must not be null.
      `right` - the second input, must not be null.
    Returns:
      result similarity.
    Throws:
      `IllegalArgumentException` - if either CharSequence input is `null`.

  - ### apply

    public <E> Double apply(SimilarityInput<E> left, SimilarityInput<E> right)
    Computes the Jaro Winkler Similarity between two character sequences.

        sim.apply(null, null)          = Throws IllegalArgumentException
        sim.apply("foo", null)         = Throws IllegalArgumentException
        sim.apply(null, "foo")         = Throws IllegalArgumentException
        sim.apply("", "")              = 1.0
        sim.apply("foo", "foo")        = 1.0
        sim.apply("foo", "foo ")       = 0.94
        sim.apply("foo", "foo  ")      = 0.91
        sim.apply("foo", " foo ")      = 0.87
        sim.apply("foo", "  foo")      = 0.51
        sim.apply("", "a")             = 0.0
        sim.apply("aaapppp", "")       = 0.0
        sim.apply("frog", "fog")       = 0.93
        sim.apply("fly", "ant")        = 0.0
        sim.apply("elephant", "hippo") = 0.44
        sim.apply("hippo", "elephant") = 0.44
        sim.apply("hippo", "zzzzzzzz") = 0.0
        sim.apply("hello", "hallo")    = 0.88
        sim.apply("ABC Corporation", "ABC Corp") = 0.91
        sim.apply("D N H Enterprises Inc", "D & H Enterprises, Inc.") = 0.95
        sim.apply("My Gym Children's Fitness Center", "My Gym. Childrens Fitness") = 0.92
        sim.apply("PENNSYLVANIA", "PENNCISYLVNIA") = 0.88

    Type Parameters:
      `E` - The type of similarity score unit.
    Parameters:
      `left` - the first input, must not be null.
      `right` - the second input, must not be null.
    Returns:
      result similarity.
    Throws:
      `IllegalArgumentException` - if either CharSequence input is `null`.
    Since:
      1.13.0