org.apache.solr.search.similarities.DFISimilarityFactory Maven / Gradle / Ivy
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* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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package org.apache.solr.search.similarities;
import org.apache.lucene.search.similarities.DFISimilarity;
import org.apache.lucene.search.similarities.Independence;
import org.apache.lucene.search.similarities.IndependenceChiSquared;
import org.apache.lucene.search.similarities.IndependenceSaturated;
import org.apache.lucene.search.similarities.IndependenceStandardized;
import org.apache.lucene.search.similarities.Similarity;
import org.apache.solr.common.params.SolrParams;
import org.apache.solr.schema.SimilarityFactory;
/**
* Factory for {@link DFISimilarity}
*
* You must specify the measure of divergence from independence ("independenceMeasure")
*
* - "Standardized": {@link IndependenceStandardized}
* - "Saturated": {@link IndependenceSaturated}
* - "ChiSquared": {@link IndependenceChiSquared}
*
* Optional settings:
*
* - discountOverlaps (bool): Sets {@link org.apache.lucene.search.similarities.SimilarityBase#setDiscountOverlaps(boolean)}
*
*
* @lucene.experimental
*/
public class DFISimilarityFactory extends SimilarityFactory {
private boolean discountOverlaps;
private Independence independenceMeasure;
@Override
public void init(SolrParams params) {
super.init(params);
discountOverlaps = params.getBool(ClassicSimilarityFactory.DISCOUNT_OVERLAPS, true);
independenceMeasure = parseIndependenceMeasure(params.get("independenceMeasure"));
}
@Override
public Similarity getSimilarity() {
DFISimilarity sim = new DFISimilarity(independenceMeasure);
sim.setDiscountOverlaps(discountOverlaps);
return sim;
}
private Independence parseIndependenceMeasure(String expr) {
if ("ChiSquared".equals(expr)) {
return new IndependenceChiSquared();
} else if ("Standardized".equals(expr)) {
return new IndependenceStandardized();
} else if ("Saturated".equals(expr)) {
return new IndependenceSaturated();
} else {
throw new RuntimeException("Invalid independence measure: " + expr);
}
}
}