org.elasticsearch.search.suggest.phrase.LinearInterpolatingScorer Maven / Gradle / Ivy
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Elasticsearch subproject :server
/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.search.suggest.phrase;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Terms;
import org.apache.lucene.util.BytesRef;
import org.elasticsearch.search.suggest.phrase.DirectCandidateGenerator.Candidate;
import java.io.IOException;
//TODO public for tests
public final class LinearInterpolatingScorer extends WordScorer {
private final double unigramLambda;
private final double bigramLambda;
private final double trigramLambda;
public LinearInterpolatingScorer(
IndexReader reader,
Terms terms,
String field,
double realWordLikelihood,
BytesRef separator,
double trigramLambda,
double bigramLambda,
double unigramLambda
) throws IOException {
super(reader, terms, field, realWordLikelihood, separator);
double sum = unigramLambda + bigramLambda + trigramLambda;
this.unigramLambda = unigramLambda / sum;
this.bigramLambda = bigramLambda / sum;
this.trigramLambda = trigramLambda / sum;
}
double trigramLambda() {
return this.trigramLambda;
}
double bigramLambda() {
return this.bigramLambda;
}
double unigramLambda() {
return this.unigramLambda;
}
@Override
protected double scoreBigram(Candidate word, Candidate w_1) throws IOException {
join(separator, spare, w_1.term, word.term);
final long count = frequency(spare.get());
if (count < 1) {
return unigramLambda * scoreUnigram(word);
}
return bigramLambda * (count / (0.5d + w_1.termStats.totalTermFreq)) + unigramLambda * scoreUnigram(word);
}
@Override
protected double scoreTrigram(Candidate w, Candidate w_1, Candidate w_2) throws IOException {
join(separator, spare, w.term, w_1.term, w_2.term);
final long count = frequency(spare.get());
if (count < 1) {
return scoreBigram(w, w_1);
}
join(separator, spare, w.term, w_1.term);
return trigramLambda * (count / (1.d + frequency(spare.get()))) + scoreBigram(w, w_1);
}
}