org.elasticsearch.search.suggest.phrase.StupidBackoffScorer Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of elasticsearch Show documentation
Show all versions of elasticsearch Show documentation
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;
class StupidBackoffScorer extends WordScorer {
private final double discount;
StupidBackoffScorer(IndexReader reader, Terms terms, String field, double realWordLikelihood, BytesRef separator, double discount)
throws IOException {
super(reader, terms, field, realWordLikelihood, separator);
this.discount = discount;
}
double discount() {
return this.discount;
}
@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 discount * scoreUnigram(word);
}
return count / (w_1.termStats.totalTermFreq + 0.00000000001d);
}
@Override
protected double scoreTrigram(Candidate w, Candidate w_1, Candidate w_2) throws IOException {
// First see if there are bigrams. If there aren't then skip looking up the trigram. This saves lookups
// when the bigrams and trigrams are rare and we need both anyway.
join(separator, spare, w_1.term, w.term);
long bigramCount = frequency(spare.get());
if (bigramCount < 1) {
return discount * scoreUnigram(w);
}
join(separator, spare, w_2.term, w_1.term, w.term);
long trigramCount = frequency(spare.get());
if (trigramCount < 1) {
return discount * (bigramCount / (w_1.termStats.totalTermFreq + 0.00000000001d));
}
return trigramCount / (bigramCount + 0.00000000001d);
}
}