org.elasticsearch.search.suggest.phrase.LaplaceScorer Maven / Gradle / Ivy
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/*
* 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;
final class LaplaceScorer extends WordScorer {
private double alpha;
LaplaceScorer(IndexReader reader, Terms terms, String field, double realWordLikelihood, BytesRef separator, double alpha)
throws IOException {
super(reader, terms, field, realWordLikelihood, separator);
this.alpha = alpha;
}
double alpha() {
return this.alpha;
}
@Override
protected double scoreUnigram(Candidate word) throws IOException {
return (alpha + frequency(word.term)) / (vocabluarySize + alpha * numTerms);
}
@Override
protected double scoreBigram(Candidate word, Candidate w_1) throws IOException {
join(separator, spare, w_1.term, word.term);
return (alpha + frequency(spare.get())) / (w_1.termStats.totalTermFreq + alpha * numTerms);
}
@Override
protected double scoreTrigram(Candidate word, Candidate w_1, Candidate w_2) throws IOException {
join(separator, spare, w_2.term, w_1.term, word.term);
long trigramCount = frequency(spare.get());
join(separator, spare, w_1.term, word.term);
return (alpha + trigramCount) / (frequency(spare.get()) + alpha * numTerms);
}
}