/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.elasticsearch.index.similarity;
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.elasticsearch.Version;
import org.elasticsearch.common.logging.DeprecationLogger;
import org.elasticsearch.common.logging.ESLoggerFactory;
import org.elasticsearch.common.settings.Settings;
import java.util.HashMap;
import java.util.Map;
import static java.util.Collections.unmodifiableMap;
/**
* {@link SimilarityProvider} for the {@link DFISimilarity}.
* <p>
* Configuration options available:
* <ul>
* <li>independence_measure</li>
* <li>discount_overlaps</li>
* </ul>
* @see DFISimilarity For more information about configuration
*/
public class DFISimilarityProvider extends AbstractSimilarityProvider {
// the "basic models" of divergence from independence
private static final Map<String, Independence> INDEPENDENCE_MEASURES;
static {
Map<String, Independence> measures = new HashMap<>();
measures.put("standardized", new IndependenceStandardized());
measures.put("saturated", new IndependenceSaturated());
measures.put("chisquared", new IndependenceChiSquared());
INDEPENDENCE_MEASURES = unmodifiableMap(measures);
}
private final DFISimilarity similarity;
public DFISimilarityProvider(String name, Settings settings, Settings indexSettings) {
super(name);
boolean discountOverlaps = settings.getAsBooleanLenientForPreEs6Indices(
Version.indexCreated(indexSettings), "discount_overlaps", true, new DeprecationLogger(ESLoggerFactory.getLogger(getClass())));
Independence measure = parseIndependence(settings);
this.similarity = new DFISimilarity(measure);
this.similarity.setDiscountOverlaps(discountOverlaps);
}
private Independence parseIndependence(Settings settings) {
String name = settings.get("independence_measure");
Independence measure = INDEPENDENCE_MEASURES.get(name);
if (measure == null) {
throw new IllegalArgumentException("Unsupported IndependenceMeasure [" + name + "]");
}
return measure;
}
@Override
public Similarity get() {
return similarity;
}
}