Package org.apache.lucene.search

Class Scorable

java.lang.Object

org.apache.lucene.search.Scorable

Direct Known Subclasses:

FilterScorable, ScoreCachingWrappingScorer, Scorer

public abstract class Scorable
extends Object

Allows access to the score of a Query

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Scorable.ChildScorable	A child Scorer and its relationship to its parent.

Constructor Summary

Constructors

Constructor	Description
Scorable()

Method Summary

Modifier and Type	Method	Description
abstract int	docID()	Returns the doc ID that is currently being scored.
Collection<Scorable.ChildScorable>	getChildren()	Returns child sub-scorers positioned on the current document
abstract float	score()	Returns the score of the current document matching the query.
void	setMinCompetitiveScore(float minScore)	Optional method: Tell the scorer that its iterator may safely ignore all documents whose score is less than the given minScore.
float	smoothingScore(int docId)	Returns the smoothing score of the current document matching the query.

Methods inherited from class java.lang.Object

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

Constructor Detail

Scorable

public Scorable()

Method Detail

score

public abstract float score()
                     throws IOException

Returns the score of the current document matching the query.

Throws:

IOException

smoothingScore

public float smoothingScore(int docId)
                     throws IOException

Returns the smoothing score of the current document matching the query. This score is used when the query/term does not appear in the document, and behaves like an idf. The smoothing score is particularly important when the Scorer returns a product of probabilities so that the document score does not go to zero when one probability is zero. This can return 0 or a smoothing score.

Smoothing scores are described in many papers, including: Metzler, D. and Croft, W. B. , "Combining the Language Model and Inference Network Approaches to Retrieval," Information Processing and Management Special Issue on Bayesian Networks and Information Retrieval, 40(5), pp.735-750.

Throws:

IOException

docID

public abstract int docID()

Returns the doc ID that is currently being scored.

setMinCompetitiveScore

public void setMinCompetitiveScore(float minScore)
                            throws IOException

Optional method: Tell the scorer that its iterator may safely ignore all documents whose score is less than the given minScore. This is a no-op by default.

This method may only be called from collectors that use ScoreMode.TOP_SCORES, and successive calls may only set increasing values of minScore.

Throws:

IOException

getChildren

public Collection<Scorable.ChildScorable> getChildren()
                                               throws IOException

Returns child sub-scorers positioned on the current document

Throws:

IOException

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