org.apache.lucene.search.similarities

## Class NormalizationH2

- java.lang.Object
- - org.apache.lucene.search.similarities.Normalization
  - - org.apache.lucene.search.similarities.NormalizationH2

-     public class NormalizationH2
      extends Normalization

  Normalization model in which the term frequency is inversely related to the length.

  While this model is parameterless in the original article, the thesis introduces the parameterized variant. The default value for the `c` parameter is `1`.

  WARNING: This API is experimental and might change in incompatible ways in the next release.

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from class org.apache.lucene.search.similarities.Normalization

      `Normalization.NoNormalization`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `NormalizationH2()` Calls `NormalizationH2(1)`
    `NormalizationH2(float c)` Creates NormalizationH2 with the supplied parameter `c`.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `Explanation` | `explain(BasicStats stats, double tf, double len)` Returns an explanation for the normalized term frequency.
    `float` | `getC()` Returns the `c` parameter.
    `double` | `tfn(BasicStats stats, double tf, double len)` Returns the normalized term frequency.
    `String` | `toString()` Subclasses must override this method to return the code of the normalization formula.

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

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

- - ### Constructor Detail

    - #### NormalizationH2

          public NormalizationH2(float c)

      Creates NormalizationH2 with the supplied parameter `c`.
      Parameters:
        `c` - hyper-parameter that controls the term frequency normalization with respect to the document length.

    - #### NormalizationH2

          public NormalizationH2()

      Calls `NormalizationH2(1)`

  - ### Method Detail

    - #### tfn

          public final double tfn(BasicStats stats,
                                  double tf,
                                  double len)

      Description copied from class: `Normalization`
      Returns the normalized term frequency.
      Specified by:
        `tfn` in class `Normalization`
        `len` - the field length.

    - #### explain

          public Explanation explain(BasicStats stats,
                                     double tf,
                                     double len)

      Description copied from class: `Normalization`
      Returns an explanation for the normalized term frequency.

      The default normalization methods use the field length of the document and the average field length to compute the normalized term frequency. This method provides a generic explanation for such methods. Subclasses that use other statistics must override this method.

      Overrides:
        `explain` in class `Normalization`

    - #### toString

          public String toString()

      Description copied from class: `Normalization`
      Subclasses must override this method to return the code of the normalization formula. Refer to the original paper for the list.
      Specified by:
        `toString` in class `Normalization`

    - #### getC

          public float getC()

      Returns the `c` parameter.
      See Also:
        `NormalizationH2(float)`

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