org.apache.lucene.search.spell

## Class NGramDistance

- java.lang.Object
- - org.apache.lucene.search.spell.NGramDistance

- All Implemented Interfaces:
    StringDistance

      public class NGramDistance
      extends java.lang.Object
      implements StringDistance

  N-Gram version of edit distance based on paper by Grzegorz Kondrak, "N-gram similarity and distance". Proceedings of the Twelfth International Conference on String Processing and Information Retrieval (SPIRE 2005), pp. 115-126, Buenos Aires, Argentina, November 2005. http://www.cs.ualberta.ca/~kondrak/papers/spire05.pdf This implementation uses the position-based optimization to compute partial matches of n-gram sub-strings and adds a null-character prefix of size n-1 so that the first character is contained in the same number of n-grams as a middle character. Null-character prefix matches are discounted so that strings with no matching characters will return a distance of 0.

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `NGramDistance()` Creates an N-Gram distance measure using n-grams of size 2.
    `NGramDistance(int size)` Creates an N-Gram distance measure using n-grams of the specified size.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `float` | `getDistance(java.lang.String source, java.lang.String target)` Returns a float between 0 and 1 based on how similar the specified strings are to one another.

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

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

- - ### Constructor Detail

    - #### NGramDistance

          public NGramDistance(int size)

      Creates an N-Gram distance measure using n-grams of the specified size.
      Parameters:
        `size` - The size of the n-gram to be used to compute the string distance.

    - #### NGramDistance

          public NGramDistance()

      Creates an N-Gram distance measure using n-grams of size 2.

  - ### Method Detail

    - #### getDistance

          public float getDistance(java.lang.String source,
                                   java.lang.String target)

      Description copied from interface: `StringDistance`
      Returns a float between 0 and 1 based on how similar the specified strings are to one another. Returning a value of 1 means the specified strings are identical and 0 means the string are maximally different.
      Specified by:
        `getDistance` in interface `StringDistance`
      Parameters:
        `source` - The first string.
        `target` - The second string.
      Returns:
        a float between 0 and 1 based on how similar the specified strings are to one another.

Copyright © 2000-2016 Apache Software Foundation. All Rights Reserved.