Lucene example source code file (TestMoreLikeThis.java)

This example Lucene source code file (TestMoreLikeThis.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Lucene tags/keywords

booleanclause, booleanquery, booleanquery, document, exception, expected, io, ioexception, map, morelikethis, morelikethis, string, string, termquery, termquery, util

The Lucene TestMoreLikeThis.java source code

package org.apache.lucene.search.similar;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * 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
 *
 * 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.
 */

import java.io.IOException;
import java.io.StringReader;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.lucene.analysis.MockAnalyzer;
import org.apache.lucene.analysis.MockTokenizer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.RandomIndexWriter;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.store.Directory;
import org.apache.lucene.util.LuceneTestCase;

public class TestMoreLikeThis extends LuceneTestCase {
  private Directory directory;
  private IndexReader reader;
  private IndexSearcher searcher;
  
  @Override
  public void setUp() throws Exception {
    super.setUp();
    directory = newDirectory();
    RandomIndexWriter writer = new RandomIndexWriter(random, directory);
    
    // Add series of docs with specific information for MoreLikeThis
    addDoc(writer, "lucene");
    addDoc(writer, "lucene release");

    reader = writer.getReader();
    writer.close();
    searcher = newSearcher(reader);
  }
  
  @Override
  public void tearDown() throws Exception {
    reader.close();
    searcher.close();
    directory.close();
    super.tearDown();
  }
  
  private void addDoc(RandomIndexWriter writer, String text) throws IOException {
    Document doc = new Document();
    doc.add(newField("text", text, Field.Store.YES, Field.Index.ANALYZED));
    writer.addDocument(doc);
  }
  
  public void testBoostFactor() throws Throwable {
    Map<String,Float> originalValues = getOriginalValues();
    
    MoreLikeThis mlt = new MoreLikeThis(reader);
    mlt.setAnalyzer(new MockAnalyzer(random, MockTokenizer.WHITESPACE, false));
    mlt.setMinDocFreq(1);
    mlt.setMinTermFreq(1);
    mlt.setMinWordLen(1);
    mlt.setFieldNames(new String[] {"text"});
    mlt.setBoost(true);
    
    // this mean that every term boost factor will be multiplied by this
    // number
    float boostFactor = 5;
    mlt.setBoostFactor(boostFactor);
    
    BooleanQuery query = (BooleanQuery) mlt.like(new StringReader(
        "lucene release"));
    List<BooleanClause> clauses = query.clauses();
    
    assertEquals("Expected " + originalValues.size() + " clauses.",
        originalValues.size(), clauses.size());
    
    for (int i = 0; i < clauses.size(); i++) {
      BooleanClause clause = clauses.get(i);
      TermQuery tq = (TermQuery) clause.getQuery();
      Float termBoost = originalValues.get(tq.getTerm().text());
      assertNotNull("Expected term " + tq.getTerm().text(), termBoost);
      
      float totalBoost = termBoost.floatValue() * boostFactor;
      assertEquals("Expected boost of " + totalBoost + " for term '"
          + tq.getTerm().text() + "' got " + tq.getBoost(), totalBoost, tq
          .getBoost(), 0.0001);
    }
  }
  
  private Map<String,Float> getOriginalValues() throws IOException {
    Map<String,Float> originalValues = new HashMap();
    MoreLikeThis mlt = new MoreLikeThis(reader);
    mlt.setAnalyzer(new MockAnalyzer(random, MockTokenizer.WHITESPACE, false));
    mlt.setMinDocFreq(1);
    mlt.setMinTermFreq(1);
    mlt.setMinWordLen(1);
    mlt.setFieldNames(new String[] {"text"});
    mlt.setBoost(true);
    BooleanQuery query = (BooleanQuery) mlt.like(new StringReader(
        "lucene release"));
    List<BooleanClause> clauses = query.clauses();
    
    for (int i = 0; i < clauses.size(); i++) {
      BooleanClause clause = clauses.get(i);
      TermQuery tq = (TermQuery) clause.getQuery();
      originalValues.put(tq.getTerm().text(), Float.valueOf(tq.getBoost()));
    }
    return originalValues;
  }
}