org.apache.lucene.search.similarities

## Class BasicModelP

- java.lang.Object
- - org.apache.lucene.search.similarities.BasicModel
  - - org.apache.lucene.search.similarities.BasicModelP

-     public class BasicModelP
      extends BasicModel

  Implements the Poisson approximation for the binomial model for DFR.
  WARNING: This API is experimental and might change in incompatible ways in the next release.

    WARNING: for terms that do not meet the expected random distribution (e.g. stopwords), this model may give poor performance, such as abnormally high scores for low tf values.

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected static double` | `LOG2_E` `log2(Math.E)`, precomputed.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `BasicModelP()` Sole constructor: parameter-free

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `float` | `score(BasicStats stats, float tfn)` Returns the informative content score.
    `String` | `toString()` Subclasses must override this method to return the code of the basic model formula.

    - ### Methods inherited from class org.apache.lucene.search.similarities.BasicModel

      `explain`

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

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

- - ### Field Detail

    - #### LOG2_E

          protected static double LOG2_E

      `log2(Math.E)`, precomputed.

  - ### Constructor Detail

    - #### BasicModelP

          public BasicModelP()

      Sole constructor: parameter-free

  - ### Method Detail

    - #### score

          public final float score(BasicStats stats,
                                   float tfn)

      Description copied from class: `BasicModel`
      Returns the informative content score.
      Specified by:
        `score` in class `BasicModel`

    - #### toString

          public String toString()

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

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