Package org.apache.lucene.misc.search.similarity

Class LegacyBM25Similarity

java.lang.Object

org.apache.lucene.search.similarities.Similarity

org.apache.lucene.misc.search.similarity.LegacyBM25Similarity

@Deprecated
public final class LegacyBM25Similarity
extends org.apache.lucene.search.similarities.Similarity

Deprecated.

BM25Similarity should be used instead

Similarity that behaves like BM25Similarity while also applying the k1+1 factor to the numerator of the scoring formula

See Also:

• BM25Similarity

Nested Class Summary

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

org.apache.lucene.search.similarities.Similarity.SimScorer

Constructor Summary

Constructors

Constructor	Description
LegacyBM25Similarity()	Deprecated. BM25 with these default values: k1 = 1.2 b = 0.75 discountOverlaps = true
LegacyBM25Similarity(float k1, float b)	Deprecated. BM25 with the supplied parameter values.
LegacyBM25Similarity(float k1, float b, boolean discountOverlaps)	Deprecated. BM25 with the supplied parameter values.

Method Summary

Modifier and Type	Method	Description
long	computeNorm(org.apache.lucene.index.FieldInvertState state)	Deprecated.
final float	getB()	Deprecated. Returns the b parameter
boolean	getDiscountOverlaps()	Deprecated. Returns true if overlap tokens are discounted from the document's length.
final float	getK1()	Deprecated. Returns the k1 parameter
org.apache.lucene.search.similarities.Similarity.SimScorer	scorer(float boost, org.apache.lucene.search.CollectionStatistics collectionStats, org.apache.lucene.search.TermStatistics... termStats)	Deprecated.
String	toString()	Deprecated.

Methods inherited from class java.lang.Object

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

Constructor Details

LegacyBM25Similarity

public LegacyBM25Similarity()

Deprecated.

BM25 with these default values:

• k1 = 1.2
• b = 0.75
• discountOverlaps = true

LegacyBM25Similarity

public LegacyBM25Similarity(float k1,
 float b)

Deprecated.

BM25 with the supplied parameter values.

Parameters:

k1 - Controls non-linear term frequency normalization (saturation).

b - Controls to what degree document length normalizes tf values.

Throws:

IllegalArgumentException - if k1 is infinite or negative, or if b is not within the range [0..1]

LegacyBM25Similarity

public LegacyBM25Similarity(float k1,
 float b,
 boolean discountOverlaps)

Deprecated.

BM25 with the supplied parameter values.

Parameters:

k1 - Controls non-linear term frequency normalization (saturation).

b - Controls to what degree document length normalizes tf values.

discountOverlaps - True if overlap tokens (tokens with a position of increment of zero) are discounted from the document's length.

Throws:

IllegalArgumentException - if k1 is infinite or negative, or if b is not within the range [0..1]

Method Details

computeNorm

public long computeNorm(org.apache.lucene.index.FieldInvertState state)

Deprecated.

Specified by:

computeNorm in class org.apache.lucene.search.similarities.Similarity

scorer

public org.apache.lucene.search.similarities.Similarity.SimScorer scorer(float boost,
 org.apache.lucene.search.CollectionStatistics collectionStats,
 org.apache.lucene.search.TermStatistics... termStats)

Deprecated.

Specified by:

scorer in class org.apache.lucene.search.similarities.Similarity

getK1

public final float getK1()

Deprecated.

Returns the k1 parameter

See Also:

• LegacyBM25Similarity(float, float)

getB

public final float getB()

Deprecated.

Returns the b parameter

See Also:

• LegacyBM25Similarity(float, float)

getDiscountOverlaps

public boolean getDiscountOverlaps()

Deprecated.

Returns true if overlap tokens are discounted from the document's length.

See Also:

• LegacyBM25Similarity(float, float, boolean)

toString

public String toString()

Deprecated.

Overrides:

toString in class Object