Lucene 4.8

package com.fox.facet;

/*
 * 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.util.ArrayList;
import java.util.List;

import org.apache.lucene.analysis.core.WhitespaceAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.facet.DrillDownQuery;
import org.apache.lucene.facet.DrillSideways;
import org.apache.lucene.facet.DrillSideways.DrillSidewaysResult;
import org.apache.lucene.facet.FacetField;
import org.apache.lucene.facet.FacetResult;
import org.apache.lucene.facet.Facets;
import org.apache.lucene.facet.FacetsCollector;
import org.apache.lucene.facet.FacetsConfig;
import org.apache.lucene.facet.taxonomy.FastTaxonomyFacetCounts;
import org.apache.lucene.facet.taxonomy.TaxonomyReader;
import org.apache.lucene.facet.taxonomy.directory.DirectoryTaxonomyReader;
import org.apache.lucene.facet.taxonomy.directory.DirectoryTaxonomyWriter;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.MatchAllDocsQuery;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.RAMDirectory;
import org.apache.lucene.util.Version;

/** Shows simple usage of faceted indexing and search. */
public class SimpleFacetsExample48 {

    private final Directory indexDir = new RAMDirectory();
    private final Directory taxoDir = new RAMDirectory();
    private final FacetsConfig config = new FacetsConfig();

    /** Empty constructor */
    public SimpleFacetsExample48() {
        config.setHierarchical("Publish Date", true);
    }

    /** Build the example index. */
    private void index() throws IOException {
        IndexWriter indexWriter = new IndexWriter(indexDir, new IndexWriterConfig(Version.LUCENE_48, new WhitespaceAnalyzer(
                Version.LUCENE_48)));

        // Writes facet ords to a separate directory from the main index
        DirectoryTaxonomyWriter taxoWriter = new DirectoryTaxonomyWriter(taxoDir);

        Document doc = new Document();
        doc.add(new FacetField("Author", "Bob"));
        doc.add(new FacetField("Publish Date", "2010", "10", "15"));
        indexWriter.addDocument(config.build(taxoWriter, doc));

        doc = new Document();
        doc.add(new FacetField("Author", "Lisa"));
        doc.add(new FacetField("Publish Date", "2010", "10", "20"));
        indexWriter.addDocument(config.build(taxoWriter, doc));

        doc = new Document();
        doc.add(new FacetField("Author", "Lisa"));
        doc.add(new FacetField("Publish Date", "2012", "1", "1"));
        indexWriter.addDocument(config.build(taxoWriter, doc));

        doc = new Document();
        doc.add(new FacetField("Author", "Susan"));
        doc.add(new FacetField("Publish Date", "2012", "1", "7"));
        indexWriter.addDocument(config.build(taxoWriter, doc));

        doc = new Document();
        doc.add(new FacetField("Author", "Frank"));
        doc.add(new FacetField("Publish Date", "1999", "5", "5"));
        indexWriter.addDocument(config.build(taxoWriter, doc));

        indexWriter.close();
        taxoWriter.close();
    }

    /** User runs a query and counts facets. */
    private List<FacetResult> facetsWithSearch() throws IOException {
        DirectoryReader indexReader = DirectoryReader.open(indexDir);
        IndexSearcher searcher = new IndexSearcher(indexReader);
        TaxonomyReader taxoReader = new DirectoryTaxonomyReader(taxoDir);

        FacetsCollector fc = new FacetsCollector();

        // MatchAllDocsQuery is for "browsing" (counts facets
        // for all non-deleted docs in the index); normally
        // you'd use a "normal" query:
        FacetsCollector.search(searcher, new MatchAllDocsQuery(), 10, fc);

        // Retrieve results
        List<FacetResult> results = new ArrayList<FacetResult>();

        // Count both "Publish Date" and "Author" dimensions
        Facets facets = new FastTaxonomyFacetCounts(taxoReader, config, fc);
        results.add(facets.getTopChildren(10, "Author"));
        results.add(facets.getTopChildren(10, "Publish Date"));

        indexReader.close();
        taxoReader.close();

        return results;
    }

    /**
     * User runs a query and counts facets only without collecting the matching
     * documents.
     */
    private List<FacetResult> facetsOnly() throws IOException {
        DirectoryReader indexReader = DirectoryReader.open(indexDir);
        IndexSearcher searcher = new IndexSearcher(indexReader);
        TaxonomyReader taxoReader = new DirectoryTaxonomyReader(taxoDir);

        FacetsCollector fc = new FacetsCollector();

        // MatchAllDocsQuery is for "browsing" (counts facets
        // for all non-deleted docs in the index); normally
        // you'd use a "normal" query:
        searcher.search(new MatchAllDocsQuery(), null /* Filter */, fc);

        // Retrieve results
        List<FacetResult> results = new ArrayList<FacetResult>();

        // Count both "Publish Date" and "Author" dimensions
        Facets facets = new FastTaxonomyFacetCounts(taxoReader, config, fc);

        results.add(facets.getTopChildren(10, "Author"));
        results.add(facets.getTopChildren(10, "Publish Date"));

        indexReader.close();
        taxoReader.close();

        return results;
    }

    /**
     * User drills down on 'Publish Date/2010', and we return facets for
     * 'Author'
     */
    private FacetResult drillDown() throws IOException {
        DirectoryReader indexReader = DirectoryReader.open(indexDir);
        IndexSearcher searcher = new IndexSearcher(indexReader);
        TaxonomyReader taxoReader = new DirectoryTaxonomyReader(taxoDir);

        // Passing no baseQuery means we drill down on all
        // documents ("browse only"):
        DrillDownQuery q = new DrillDownQuery(config);

        // Now user drills down on Publish Date/2010:
        q.add("Publish Date", "2010");
        FacetsCollector fc = new FacetsCollector();
        FacetsCollector.search(searcher, q, 10, fc);

        // Retrieve results
        Facets facets = new FastTaxonomyFacetCounts(taxoReader, config, fc);
        FacetResult result = facets.getTopChildren(10, "Author");

        indexReader.close();
        taxoReader.close();

        return result;
    }

    /**
     * User drills down on 'Publish Date/2010', and we return facets for both
     * 'Publish Date' and 'Author', using DrillSideways.
     */
    private List<FacetResult> drillSideways() throws IOException {
        DirectoryReader indexReader = DirectoryReader.open(indexDir);
        IndexSearcher searcher = new IndexSearcher(indexReader);
        TaxonomyReader taxoReader = new DirectoryTaxonomyReader(taxoDir);

        // Passing no baseQuery means we drill down on all
        // documents ("browse only"):
        DrillDownQuery q = new DrillDownQuery(config);

        // Now user drills down on Publish Date/2010:
        q.add("Publish Date", "2010");

        DrillSideways ds = new DrillSideways(searcher, config, taxoReader);
        DrillSidewaysResult result = ds.search(q, 10);

        // Retrieve results
        List<FacetResult> facets = result.facets.getAllDims(10);

        indexReader.close();
        taxoReader.close();

        return facets;
    }

    /** Runs the search example. */
    public List<FacetResult> runFacetOnly() throws IOException {
        index();
        return facetsOnly();
    }

    /** Runs the search example. */
    public List<FacetResult> runSearch() throws IOException {
        index();
        return facetsWithSearch();
    }

    /** Runs the drill-down example. */
    public FacetResult runDrillDown() throws IOException {
        index();
        return drillDown();
    }

    /** Runs the drill-sideways example. */
    public List<FacetResult> runDrillSideways() throws IOException {
        index();
        return drillSideways();
    }

    /** Runs the search and drill-down examples and prints the results. */
    public static void main(String[] args) throws Exception {
        System.out.println("Facet counting example:");
        System.out.println("-----------------------");
        SimpleFacetsExample48 example1 = new SimpleFacetsExample48();
        List<FacetResult> results1 = example1.runFacetOnly();
        System.out.println("Author: " + results1.get(0));
        System.out.println("Publish Date: " + results1.get(1));

        System.out.println("Facet counting example (combined facets and search):");
        System.out.println("-----------------------");
        SimpleFacetsExample48 example = new SimpleFacetsExample48();
        List<FacetResult> results = example.runSearch();
        System.out.println("Author: " + results.get(0));
        System.out.println("Publish Date: " + results.get(1));

        System.out.println("
");
        System.out.println("Facet drill-down example (Publish Date/2010):");
        System.out.println("---------------------------------------------");
        System.out.println("Author: " + example.runDrillDown());

        System.out.println("
");
        System.out.println("Facet drill-sideways example (Publish Date/2010):");
        System.out.println("---------------------------------------------");
        for (FacetResult result : example.runDrillSideways()) {
            System.out.println(result);
        }
    }

}

Result:

Facet counting example:
-----------------------
Author: dim=Author path=[] value=5 childCount=4
  Lisa (2)
  Bob (1)
  Susan (1)
  Frank (1)

Publish Date: dim=Publish Date path=[] value=5 childCount=3
  2010 (2)
  2012 (2)
  1999 (1)

Facet counting example (combined facets and search):
-----------------------
Author: dim=Author path=[] value=5 childCount=4
  Lisa (2)
  Bob (1)
  Susan (1)
  Frank (1)

Publish Date: dim=Publish Date path=[] value=5 childCount=3
  2010 (2)
  2012 (2)
  1999 (1)



Facet drill-down example (Publish Date/2010):
---------------------------------------------
Author: dim=Author path=[] value=4 childCount=2
  Bob (2)
  Lisa (2)



Facet drill-sideways example (Publish Date/2010):
---------------------------------------------
dim=Publish Date path=[] value=15 childCount=3
  2010 (6)
  2012 (6)
  1999 (3)

dim=Author path=[] value=6 childCount=2
  Bob (3)
  Lisa (3)