Package org.apache.commons.text.similarity

## Class JaroWinklerDistance

- java.lang.Object
- - org.apache.commons.text.similarity.JaroWinklerDistance

- All Implemented Interfaces:
    `SimilarityScore<Double>`

      public class JaroWinklerDistance
      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 http://en.wikipedia.org/wiki/Jaro%E2%80%93Winkler_distance.

  This code has been adapted from Apache Commons Lang 3.3.

  Since:
    1.0

- - ### Field Summary

    Fields
    Modifier and Type | Field | Description
    --- | --- | ---
    `static int` | `INDEX_NOT_FOUND` | Represents a failed index search.

  - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `JaroWinklerDistance()` |

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `Double` | `apply​(CharSequence left, CharSequence right)` | Find the Jaro Winkler Distance which indicates the similarity score between two CharSequences.
    `protected static int[]` | `matches​(CharSequence first, CharSequence second)` | This method returns the Jaro-Winkler string matches, half transpositions, prefix array.

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### INDEX_NOT_FOUND

          public static final int INDEX_NOT_FOUND

      Represents a failed index search.
      See Also:
        Constant Field Values

  - ### Constructor Detail

    - #### JaroWinklerDistance

          public JaroWinklerDistance()

  - ### Method Detail

    - #### apply

          public Double apply​(CharSequence left,
                              CharSequence right)

      Find the Jaro Winkler Distance which indicates the similarity score between two CharSequences.

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

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

    - #### matches

          protected static int[] matches​(CharSequence first,
                                         CharSequence second)

      This method returns the Jaro-Winkler string matches, half transpositions, prefix array.
      Parameters:
        `first` - the first string to be matched
        `second` - the second string to be matched
      Returns:
        mtp array containing: matches, half transpositions, and prefix