org.elasticsearch.search.suggest.phrase.LinearInterpoatingScorer Maven / Gradle / Ivy
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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.SuggestUtils;
import org.elasticsearch.search.suggest.phrase.DirectCandidateGenerator.Candidate;
import java.io.IOException;
//TODO public for tests
public final class LinearInterpoatingScorer extends WordScorer {
private final double unigramLambda;
private final double bigramLambda;
private final double trigramLambda;
public LinearInterpoatingScorer(IndexReader reader, Terms terms, String field, double realWordLikelyhood, BytesRef separator, double trigramLambda, double bigramLambda, double unigramLambda)
throws IOException {
super(reader, terms, field, realWordLikelyhood, separator);
double sum = unigramLambda + bigramLambda + trigramLambda;
this.unigramLambda = unigramLambda / sum;
this.bigramLambda = bigramLambda / sum;
this.trigramLambda = trigramLambda / sum;
}
@Override
protected double scoreBigram(Candidate word, Candidate w_1) throws IOException {
SuggestUtils.join(separator, spare, w_1.term, word.term);
final long count = frequency(spare);
if (count < 1) {
return unigramLambda * scoreUnigram(word);
}
return bigramLambda * (count / (0.5d+w_1.frequency)) + unigramLambda * scoreUnigram(word);
}
@Override
protected double scoreTrigram(Candidate w, Candidate w_1, Candidate w_2) throws IOException {
SuggestUtils.join(separator, spare, w.term, w_1.term, w_2.term);
final long count = frequency(spare);
if (count < 1) {
return scoreBigram(w, w_1);
}
SuggestUtils.join(separator, spare, w.term, w_1.term);
return trigramLambda * (count / (1.d+frequency(spare))) + scoreBigram(w, w_1);
}
}