public class BooleanSimilarity extends Similarity
SimilarityBase
and BM25Similarity
with
discounted overlaps
so that the Similarity
can be changed after the index has been
created.Similarity.SimScorer
Constructor and Description 

BooleanSimilarity()
Sole constructor

Modifier and Type  Method and Description 

long 
computeNorm(FieldInvertState state)
Computes the normalization value for a field, given the accumulated
state of term processing for this field (see
FieldInvertState ). 
Similarity.SimScorer 
scorer(float boost,
CollectionStatistics collectionStats,
TermStatistics... termStats)
Compute any collectionlevel weight (e.g.

public long computeNorm(FieldInvertState state)
Similarity
FieldInvertState
).
Matches in longer fields are less precise, so implementations of this
method usually set smaller values when state.getLength()
is large,
and larger values when state.getLength()
is small.
Note that for a given termdocument frequency, greater unsigned norms
must produce scores that are lower or equal, ie. for two encoded norms
n1
and n2
so that
Long.compareUnsigned(n1, n2) > 0
then
SimScorer.score(freq, n1) <= SimScorer.score(freq, n2)
for any legal freq
.
0
is not a legal norm, so 1
is the norm that produces
the highest scores.
computeNorm
in class Similarity
state
 current processing state for this fieldpublic Similarity.SimScorer scorer(float boost, CollectionStatistics collectionStats, TermStatistics... termStats)
Similarity
scorer
in class Similarity
boost
 a multiplicative factor to apply to the produces scorescollectionStats
 collectionlevel statistics, such as the number of tokens in the collection.termStats
 termlevel statistics, such as the document frequency of a term across the collection.Copyright © 20002020 Apache Software Foundation. All Rights Reserved.