Class TermScorer
- java.lang.Object
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- org.apache.lucene.search.Scorable
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- org.apache.lucene.search.Scorer
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- org.apache.lucene.search.TermScorer
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public final class TermScorer extends Scorer
Expert: AScorerfor documents matching aTerm.- NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.
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Nested Class Summary
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Nested classes/interfaces inherited from class org.apache.lucene.search.Scorable
Scorable.ChildScorable
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Constructor Summary
Constructors Constructor Description TermScorer(Weight weight, ImpactsEnum impactsEnum, LeafSimScorer docScorer, boolean topLevelScoringClause)Construct aTermScorerthat will use impacts to skip blocks of non-competitive documents.TermScorer(Weight weight, PostingsEnum postingsEnum, LeafSimScorer docScorer)Construct aTermScorerthat will iterate all documents.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description intadvanceShallow(int target)Advance to the block of documents that containstargetin order to get scoring information about this block.intdocID()Returns the doc ID that is currently being scored.intfreq()Returns term frequency in the current document.floatgetMaxScore(int upTo)Return the maximum score that documents between the lasttargetthat this iterator wasshallow-advancedto included andupToincluded.DocIdSetIteratoriterator()Return aDocIdSetIteratorover matching documents.floatscore()Returns the score of the current document matching the query.voidsetMinCompetitiveScore(float minScore)Optional method: Tell the scorer that its iterator may safely ignore all documents whose score is less than the givenminScore.floatsmoothingScore(int docId)Returns the smoothing score of the current document matching the query.StringtoString()Returns a string representation of thisTermScorer.-
Methods inherited from class org.apache.lucene.search.Scorer
getWeight, twoPhaseIterator
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Methods inherited from class org.apache.lucene.search.Scorable
getChildren
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Constructor Detail
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TermScorer
public TermScorer(Weight weight, PostingsEnum postingsEnum, LeafSimScorer docScorer)
Construct aTermScorerthat will iterate all documents.
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TermScorer
public TermScorer(Weight weight, ImpactsEnum impactsEnum, LeafSimScorer docScorer, boolean topLevelScoringClause)
Construct aTermScorerthat will use impacts to skip blocks of non-competitive documents.
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Method Detail
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docID
public int docID()
Description copied from class:ScorableReturns the doc ID that is currently being scored.
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freq
public final int freq() throws IOExceptionReturns term frequency in the current document.- Throws:
IOException
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iterator
public DocIdSetIterator iterator()
Description copied from class:ScorerReturn aDocIdSetIteratorover matching documents.The returned iterator will either be positioned on
-1if no documents have been scored yet,DocIdSetIterator.NO_MORE_DOCSif 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.
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score
public float score() throws IOExceptionDescription copied from class:ScorableReturns the score of the current document matching the query.- Specified by:
scorein classScorable- Throws:
IOException
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smoothingScore
public float smoothingScore(int docId) throws IOExceptionDescription copied from class:ScorableReturns 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:
smoothingScorein classScorable- Throws:
IOException
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advanceShallow
public int advanceShallow(int target) throws IOExceptionDescription copied from class:ScorerAdvance to the block of documents that containstargetin order to get scoring information about this block. This method is implicitly called byDocIdSetIterator.advance(int)andDocIdSetIterator.nextDoc()on the returned doc ID. Calling this method doesn't modify the currentDocIdSetIterator.docID(). It returns a number that is greater than or equal to all documents contained in the current block, but less than any doc IDS of the next block.targetmust be >=Scorable.docID()as well as all targets that have been passed toScorer.advanceShallow(int)so far.- Overrides:
advanceShallowin classScorer- Throws:
IOException
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getMaxScore
public float getMaxScore(int upTo) throws IOExceptionDescription copied from class:ScorerReturn the maximum score that documents between the lasttargetthat this iterator wasshallow-advancedto included andupToincluded.- Specified by:
getMaxScorein classScorer- Throws:
IOException
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setMinCompetitiveScore
public void setMinCompetitiveScore(float minScore)
Description copied from class:ScorableOptional method: Tell the scorer that its iterator may safely ignore all documents whose score is less than the givenminScore. 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 ofminScore.- Overrides:
setMinCompetitiveScorein classScorable
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