Class LMSimilarity
- java.lang.Object
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- org.apache.lucene.search.similarities.Similarity
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- org.apache.lucene.search.similarities.SimilarityBase
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- org.apache.lucene.search.similarities.LMSimilarity
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- Direct Known Subclasses:
LMDirichletSimilarity,LMJelinekMercerSimilarity
public abstract class LMSimilarity extends SimilarityBase
Abstract superclass for language modeling Similarities. The following inner types are introduced:LMSimilarity.LMStats, which defines a new statistic, the probability that the collection language model generates the current term;LMSimilarity.CollectionModel, which is a strategy interface for object that compute the collection language modelp(w|C);LMSimilarity.DefaultCollectionModel, an implementation of the former, that computes the term probability as the number of occurrences of the term in the collection, divided by the total number of tokens.
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Nested Class Summary
Nested Classes Modifier and Type Class Description static interfaceLMSimilarity.CollectionModelA strategy for computing the collection language model.static classLMSimilarity.DefaultCollectionModelModelsp(w|C)as the number of occurrences of the term in the collection, divided by the total number of tokens+ 1.static classLMSimilarity.LMStatsStores the collection distribution of the current term.-
Nested classes/interfaces inherited from class org.apache.lucene.search.similarities.Similarity
Similarity.SimScorer, Similarity.SimWeight
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Constructor Summary
Constructors Constructor Description LMSimilarity()Creates a new instance with the default collection language model.LMSimilarity(LMSimilarity.CollectionModel collectionModel)Creates a new instance with the specified collection language model.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description abstract java.lang.StringgetName()Returns the name of the LM method.java.lang.StringtoString()Returns the name of the LM method.-
Methods inherited from class org.apache.lucene.search.similarities.SimilarityBase
computeNorm, computeWeight, getDiscountOverlaps, log2, setDiscountOverlaps, simScorer
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Methods inherited from class org.apache.lucene.search.similarities.Similarity
coord, queryNorm
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Constructor Detail
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LMSimilarity
public LMSimilarity(LMSimilarity.CollectionModel collectionModel)
Creates a new instance with the specified collection language model.
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LMSimilarity
public LMSimilarity()
Creates a new instance with the default collection language model.
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Method Detail
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getName
public abstract java.lang.String getName()
Returns the name of the LM method. The values of the parameters should be included as well.Used in
.toString()
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toString
public java.lang.String toString()
Returns the name of the LM method. If a custom collection model strategy is used, its name is included as well.- Specified by:
toStringin classSimilarityBase- See Also:
getName(),LMSimilarity.CollectionModel.getName(),LMSimilarity.DefaultCollectionModel
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