org.apache.lucene.search

Class IndriScorer

java.lang.Object

org.apache.lucene.search.Scorable

org.apache.lucene.search.Scorer

org.apache.lucene.search.IndriScorer

Direct Known Subclasses:

IndriDisjunctionScorer

public abstract class IndriScorer
extends Scorer

The Indri parent scorer that stores the boost so that IndriScorers can use the boost outside of the term.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.search.Scorable

Scorable.ChildScorable

Field Summary

Fields inherited from class org.apache.lucene.search.Scorer

weight

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	IndriScorer(Weight weight, float boost)

Method Summary

Modifier and Type	Method and Description
abstract int	docID() Returns the doc ID that is currently being scored.
float	getBoost()
abstract float	getMaxScore(int upTo) Return the maximum score that documents between the last target that this iterator was shallow-advanced to included and upTo included.
abstract DocIdSetIterator	iterator() Return a DocIdSetIterator over matching documents.
abstract float	score() Returns the score of the current document matching the query.
abstract float	smoothingScore(int docId) Returns the smoothing score of the current document matching the query.

Methods inherited from class org.apache.lucene.search.Scorer

advanceShallow, getWeight, twoPhaseIterator

Methods inherited from class org.apache.lucene.search.Scorable

getChildren, setMinCompetitiveScore

Methods inherited from class java.lang.Object

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

Constructor Detail

IndriScorer

protected IndriScorer(Weight weight,
                      float boost)

Method Detail

iterator

public abstract DocIdSetIterator iterator()

Description copied from class: Scorer

Return a DocIdSetIterator over matching documents. The returned iterator will either be positioned on -1 if no documents have been scored yet, DocIdSetIterator.NO_MORE_DOCS if all documents have been scored already, or the last document id that has been scored otherwise. The returned iterator is a view: calling this method several times will return iterators that have the same state.

Specified by:

iterator in class Scorer

getMaxScore

public abstract float getMaxScore(int upTo)
                           throws IOException

Description copied from class: Scorer

Return the maximum score that documents between the last target that this iterator was shallow-advanced to included and upTo included.

Specified by:

getMaxScore in class Scorer

Throws:

IOException

score

public abstract float score()
                     throws IOException

Description copied from class: Scorable

Returns the score of the current document matching the query.

Specified by:

score in class Scorable

Throws:

IOException

smoothingScore

public abstract float smoothingScore(int docId)
                              throws IOException

Description copied from class: Scorable

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.

Overrides:

smoothingScore in class Scorable

Throws:

IOException

docID

public abstract int docID()

Description copied from class: Scorable

Returns the doc ID that is currently being scored.

Specified by:

docID in class Scorable

getBoost

public float getBoost()