public class

CustomScoreProvider

extends Object
java.lang.Object
   ↳ org.apache.lucene.search.function.CustomScoreProvider

Class Overview

An instance of this subclass should be returned by getCustomScoreProvider(IndexReader), if you want to modify the custom score calculation of a CustomScoreQuery.

Since Lucene 2.9, queries operate on each segment of an Index separately, so overriding the similar (now deprecated) methods in CustomScoreQuery is no longer suitable, as the supplied doc ID is per-segment and without knowledge of the IndexReader you cannot access the document or FieldCache.@lucene.experimental

Summary

Fields
protected final IndexReader reader
Public Constructors
CustomScoreProvider(IndexReader reader)
Creates a new instance of the provider class for the given IndexReader.
Public Methods
Explanation customExplain(int doc, Explanation subQueryExpl, Explanation valSrcExpl)
Explain the custom score.
Explanation customExplain(int doc, Explanation subQueryExpl, Explanation[] valSrcExpls)
Explain the custom score.
float customScore(int doc, float subQueryScore, float[] valSrcScores)
Compute a custom score by the subQuery score and a number of ValueSourceQuery scores.
float customScore(int doc, float subQueryScore, float valSrcScore)
Compute a custom score by the subQuery score and the ValueSourceQuery score.
[Expand]
Inherited Methods
From class java.lang.Object

Fields

protected final IndexReader reader

Public Constructors

public CustomScoreProvider (IndexReader reader)

Creates a new instance of the provider class for the given IndexReader.

Public Methods

public Explanation customExplain (int doc, Explanation subQueryExpl, Explanation valSrcExpl)

Explain the custom score. Whenever overriding customScore(int, float, float), this method should also be overridden to provide the correct explanation for the part of the custom scoring.

Parameters
doc doc being explained.
subQueryExpl explanation for the sub-query part.
valSrcExpl explanation for the value source part.
Returns
  • an explanation for the custom score
Throws
IOException

public Explanation customExplain (int doc, Explanation subQueryExpl, Explanation[] valSrcExpls)

Explain the custom score. Whenever overriding customScore(int, float, float[]), this method should also be overridden to provide the correct explanation for the part of the custom scoring.

Parameters
doc doc being explained.
subQueryExpl explanation for the sub-query part.
valSrcExpls explanation for the value source part.
Returns
  • an explanation for the custom score
Throws
IOException

public float customScore (int doc, float subQueryScore, float[] valSrcScores)

Compute a custom score by the subQuery score and a number of ValueSourceQuery scores.

Subclasses can override this method to modify the custom score.

If your custom scoring is different than the default herein you should override at least one of the two customScore() methods. If the number of ValueSourceQueries is always < 2 it is sufficient to override the other customScore() method, which is simpler.

The default computation herein is a multiplication of given scores:

     ModifiedScore = valSrcScore * valSrcScores[0] * valSrcScores[1] * ...
 

Parameters
doc id of scored doc.
subQueryScore score of that doc by the subQuery.
valSrcScores scores of that doc by the ValueSourceQuery.
Returns
  • custom score.
Throws
IOException

public float customScore (int doc, float subQueryScore, float valSrcScore)

Compute a custom score by the subQuery score and the ValueSourceQuery score.

Subclasses can override this method to modify the custom score.

If your custom scoring is different than the default herein you should override at least one of the two customScore() methods. If the number of ValueSourceQueries is always < 2 it is sufficient to override this customScore() method, which is simpler.

The default computation herein is a multiplication of the two scores:

     ModifiedScore = subQueryScore * valSrcScore
 

Parameters
doc id of scored doc.
subQueryScore score of that doc by the subQuery.
valSrcScore score of that doc by the ValueSourceQuery.
Returns
  • custom score.
Throws
IOException