    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.lucene.demo.facet;
    018
    019import java.io.IOException;
    020import java.text.ParseException;
    021
    022import org.apache.lucene.analysis.core.WhitespaceAnalyzer;
    023import org.apache.lucene.document.Document;
    024import org.apache.lucene.document.Field.Store;
    025import org.apache.lucene.document.NumericDocValuesField;
    026import org.apache.lucene.document.TextField;
    027import org.apache.lucene.expressions.Expression;
    028import org.apache.lucene.expressions.SimpleBindings;
    029import org.apache.lucene.expressions.js.JavascriptCompiler;
    030import org.apache.lucene.facet.FacetField;
    031import org.apache.lucene.facet.FacetResult;
    032import org.apache.lucene.facet.Facets;
    033import org.apache.lucene.facet.FacetsCollector;
    034import org.apache.lucene.facet.FacetsConfig;
    035import org.apache.lucene.facet.taxonomy.TaxonomyFacetSumValueSource;
    036import org.apache.lucene.facet.taxonomy.TaxonomyReader;
    037import org.apache.lucene.facet.taxonomy.directory.DirectoryTaxonomyReader;
    038import org.apache.lucene.facet.taxonomy.directory.DirectoryTaxonomyWriter;
    039import org.apache.lucene.index.DirectoryReader;
    040import org.apache.lucene.index.IndexWriter;
    041import org.apache.lucene.index.IndexWriterConfig;
    042import org.apache.lucene.index.IndexWriterConfig.OpenMode;
    043import org.apache.lucene.search.IndexSearcher;
    044import org.apache.lucene.search.MatchAllDocsQuery;
    045import org.apache.lucene.search.SortField;
    046import org.apache.lucene.store.Directory;
    047import org.apache.lucene.store.RAMDirectory;
    048
    049
    050/** Shows facets aggregation by an expression. */
    051public class ExpressionAggregationFacetsExample {
    052
    053  private final Directory indexDir = new RAMDirectory();
    054  private final Directory taxoDir = new RAMDirectory();
    055  private final FacetsConfig config = new FacetsConfig();
    056
    057  /** Empty constructor */
    058  public ExpressionAggregationFacetsExample() {}
    059
    060  /** Build the example index. */
    061  private void index() throws IOException {
    062    IndexWriter indexWriter = new IndexWriter(indexDir, new IndexWriterConfig(
    063        new WhitespaceAnalyzer()).setOpenMode(OpenMode.CREATE));
    064
    065    // Writes facet ords to a separate directory from the main index
    066    DirectoryTaxonomyWriter taxoWriter = new DirectoryTaxonomyWriter(taxoDir);
    067
    068    Document doc = new Document();
    069    doc.add(new TextField("c", "foo bar", Store.NO));
    070    doc.add(new NumericDocValuesField("popularity", 5L));
    071    doc.add(new FacetField("A", "B"));
    072    indexWriter.addDocument(config.build(taxoWriter, doc));
    073
    074    doc = new Document();
    075    doc.add(new TextField("c", "foo foo bar", Store.NO));
    076    doc.add(new NumericDocValuesField("popularity", 3L));
    077    doc.add(new FacetField("A", "C"));
    078    indexWriter.addDocument(config.build(taxoWriter, doc));
    079
    080    indexWriter.close();
    081    taxoWriter.close();
    082  }
    083
    084  /** User runs a query and aggregates facets. */
    085  private FacetResult search() throws IOException, ParseException {
    086    DirectoryReader indexReader = DirectoryReader.open(indexDir);
    087    IndexSearcher searcher = new IndexSearcher(indexReader);
    088    TaxonomyReader taxoReader = new DirectoryTaxonomyReader(taxoDir);
    089
    090    // Aggregate categories by an expression that combines the document's score
    091    // and its popularity field
    092    Expression expr = JavascriptCompiler.compile("_score * sqrt(popularity)");
    093    SimpleBindings bindings = new SimpleBindings();
    094    bindings.add(new SortField("_score", SortField.Type.SCORE)); // the score of the document
    095    bindings.add(new SortField("popularity", SortField.Type.LONG)); // the value of the 'popularity' field
    096
    097    // Aggregates the facet values
    098    FacetsCollector fc = new FacetsCollector(true);
    099
    100    // MatchAllDocsQuery is for "browsing" (counts facets
    101    // for all non-deleted docs in the index); normally
    102    // you'd use a "normal" query:
    103    FacetsCollector.search(searcher, new MatchAllDocsQuery(), 10, fc);
    104
    105    // Retrieve results
    106    Facets facets = new TaxonomyFacetSumValueSource(taxoReader, config, fc, expr.getValueSource(bindings));
    107    FacetResult result = facets.getTopChildren(10, "A");
    108
    109    indexReader.close();
    110    taxoReader.close();
    111
    112    return result;
    113  }
    114
    115  /** Runs the search example. */
    116  public FacetResult runSearch() throws IOException, ParseException {
    117    index();
    118    return search();
    119  }
    120
    121  /** Runs the search and drill-down examples and prints the results. */
    122  public static void main(String[] args) throws Exception {
    123    System.out.println("Facet counting example:");
    124    System.out.println("-----------------------");
    125    FacetResult result = new ExpressionAggregationFacetsExample().runSearch();
    126    System.out.println(result);
    127  }
    128}