org.elasticsearch.search.suggest.phrase.LinearInterpolation 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.common.ParsingException;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.search.suggest.phrase.WordScorer.WordScorerFactory;
import org.elasticsearch.xcontent.ParseField;
import org.elasticsearch.xcontent.XContentBuilder;
import org.elasticsearch.xcontent.XContentParser;
import org.elasticsearch.xcontent.XContentParser.Token;
import java.io.IOException;
import java.util.Objects;
/**
* Linear interpolation smoothing model.
*
* See N-Gram
* Smoothing for details.
*
*/
public final class LinearInterpolation extends SmoothingModel {
public static final String NAME = "linear";
static final ParseField PARSE_FIELD = new ParseField(NAME);
private static final ParseField TRIGRAM_FIELD = new ParseField("trigram_lambda");
private static final ParseField BIGRAM_FIELD = new ParseField("bigram_lambda");
private static final ParseField UNIGRAM_FIELD = new ParseField("unigram_lambda");
private final double trigramLambda;
private final double bigramLambda;
private final double unigramLambda;
/**
* Creates a linear interpolation smoothing model.
*
* Note: the lambdas must sum up to one.
*
* @param trigramLambda
* the trigram lambda
* @param bigramLambda
* the bigram lambda
* @param unigramLambda
* the unigram lambda
*/
public LinearInterpolation(double trigramLambda, double bigramLambda, double unigramLambda) {
double sum = trigramLambda + bigramLambda + unigramLambda;
if (Math.abs(sum - 1.0) > 0.001) {
throw new IllegalArgumentException("linear smoothing lambdas must sum to 1");
}
this.trigramLambda = trigramLambda;
this.bigramLambda = bigramLambda;
this.unigramLambda = unigramLambda;
}
/**
* Read from a stream.
*/
public LinearInterpolation(StreamInput in) throws IOException {
trigramLambda = in.readDouble();
bigramLambda = in.readDouble();
unigramLambda = in.readDouble();
}
@Override
public void writeTo(StreamOutput out) throws IOException {
out.writeDouble(trigramLambda);
out.writeDouble(bigramLambda);
out.writeDouble(unigramLambda);
}
public double getTrigramLambda() {
return this.trigramLambda;
}
public double getBigramLambda() {
return this.bigramLambda;
}
public double getUnigramLambda() {
return this.unigramLambda;
}
@Override
protected XContentBuilder innerToXContent(XContentBuilder builder, Params params) throws IOException {
builder.field(TRIGRAM_FIELD.getPreferredName(), trigramLambda);
builder.field(BIGRAM_FIELD.getPreferredName(), bigramLambda);
builder.field(UNIGRAM_FIELD.getPreferredName(), unigramLambda);
return builder;
}
@Override
public String getWriteableName() {
return NAME;
}
@Override
protected boolean doEquals(SmoothingModel other) {
final LinearInterpolation otherModel = (LinearInterpolation) other;
return Objects.equals(trigramLambda, otherModel.trigramLambda)
&& Objects.equals(bigramLambda, otherModel.bigramLambda)
&& Objects.equals(unigramLambda, otherModel.unigramLambda);
}
@Override
protected int doHashCode() {
return Objects.hash(trigramLambda, bigramLambda, unigramLambda);
}
public static LinearInterpolation fromXContent(XContentParser parser) throws IOException {
XContentParser.Token token;
String fieldName = null;
double trigramLambda = 0.0;
double bigramLambda = 0.0;
double unigramLambda = 0.0;
while ((token = parser.nextToken()) != Token.END_OBJECT) {
if (token == XContentParser.Token.FIELD_NAME) {
fieldName = parser.currentName();
} else if (token.isValue()) {
if (TRIGRAM_FIELD.match(fieldName, parser.getDeprecationHandler())) {
trigramLambda = parser.doubleValue();
if (trigramLambda < 0) {
throw new IllegalArgumentException("trigram_lambda must be positive");
}
} else if (BIGRAM_FIELD.match(fieldName, parser.getDeprecationHandler())) {
bigramLambda = parser.doubleValue();
if (bigramLambda < 0) {
throw new IllegalArgumentException("bigram_lambda must be positive");
}
} else if (UNIGRAM_FIELD.match(fieldName, parser.getDeprecationHandler())) {
unigramLambda = parser.doubleValue();
if (unigramLambda < 0) {
throw new IllegalArgumentException("unigram_lambda must be positive");
}
} else {
throw new IllegalArgumentException("suggester[phrase][smoothing][linear] doesn't support field [" + fieldName + "]");
}
} else {
throw new ParsingException(
parser.getTokenLocation(),
"[" + NAME + "] unknown token [" + token + "] after [" + fieldName + "]"
);
}
}
return new LinearInterpolation(trigramLambda, bigramLambda, unigramLambda);
}
@Override
public WordScorerFactory buildWordScorerFactory() {
return (
IndexReader reader,
Terms terms,
String field,
double realWordLikelihood,
BytesRef separator) -> new LinearInterpolatingScorer(
reader,
terms,
field,
realWordLikelihood,
separator,
trigramLambda,
bigramLambda,
unigramLambda
);
}
}