org.apache.lucene.search.similarities

## Class LambdaDF

- java.lang.Object
- - org.apache.lucene.search.similarities.Lambda
  - - org.apache.lucene.search.similarities.LambdaDF

-     public class LambdaDF
      extends Lambda

  Computes lambda as `docFreq+1 / numberOfDocuments+1`.
  WARNING: This API is experimental and might change in incompatible ways in the next release.

- - ### Constructor Summary

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

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `Explanation` | `explain(BasicStats stats)` Explains the lambda parameter.
    `float` | `lambda(BasicStats stats)` Computes the lambda parameter.
    `String` | `toString()` Subclasses must override this method to return the code of the lambda formula.

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

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

- - ### Constructor Detail

    - #### LambdaDF

          public LambdaDF()

      Sole constructor: parameter-free

  - ### Method Detail

    - #### lambda

          public final float lambda(BasicStats stats)

      Description copied from class: `Lambda`
      Computes the lambda parameter.
      Specified by:
        `lambda` in class `Lambda`

    - #### explain

          public final Explanation explain(BasicStats stats)

      Description copied from class: `Lambda`
      Explains the lambda parameter.
      Specified by:
        `explain` in class `Lambda`

    - #### toString

          public String toString()

      Description copied from class: `Lambda`
      Subclasses must override this method to return the code of the lambda formula. Since the original paper is not very clear on this matter, and also uses the DFR naming scheme incorrectly, the codes here were chosen arbitrarily.
      Specified by:
        `toString` in class `Lambda`

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