org.apache.lucene.search.similarities

## Class DistributionSPL

- java.lang.Object
- - org.apache.lucene.search.similarities.Distribution
  - - org.apache.lucene.search.similarities.DistributionSPL

    public class DistributionSPL
    extends Distribution

The smoothed power-law (SPL) distribution for the information-based framework that is described in the original paper.

Unlike for DFR, the natural logarithm is used, as it is faster to compute and the original paper does not express any preference to a specific base.

WARNING: this model currently returns infinite scores for very small tf values and negative scores for very large tf values

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

### Constructor Summary

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

### Method Summary

All Methods Instance Methods Concrete Methods
`float` `score(BasicStats stats, float tfn, float lambda)` Computes the score.
`String` `toString()` Subclasses must override this method to return the name of the distribution.

### Methods inherited from class org.apache.lucene.search.similarities.Distribution

`explain`

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

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

### Constructor Detail

#### DistributionSPL

    public DistributionSPL()

Sole constructor: parameter-free

### Method Detail

#### score

    public final float score(BasicStats stats,
                             float tfn,
                             float lambda)

Description copied from class: `Distribution`
Computes the score.

Specified by:
  `score` in class `Distribution`

#### toString

    public String toString()

Description copied from class: `Distribution`
Subclasses must override this method to return the name of the distribution.

Specified by:
  `toString` in class `Distribution`