java 如何在 Lucene 中实现 tf-idf 和余弦相似度？

how can I implement the tf-idf and cosine similarity in Lucene?

提问by Tia Chandrawati

How can I implement the tf-idf and cosine similarity in Lucene? I'm using Lucene 4.2. The program that I've created does not use tf-idf and Cosine similaryty, it only uses TopScoreDocCollector.

如何在 Lucene 中实现 tf-idf 和余弦相似度？我正在使用 Lucene 4.2。我创建的程序不使用 tf-idf 和 Cosine 相似性，它只使用 TopScoreDocCollector。

import com.mysql.jdbc.Statement;
import java.io.BufferedReader;
import java.io.File;
import java.io.InputStreamReader;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.util.Version;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.IndexWriter;

import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.ResultSet;
import org.apache.lucene.analysis.id.IndonesianAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.*;
import org.apache.lucene.queryparser.classic.ParseException;
import org.apache.lucene.queryparser.classic.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TopScoreDocCollector;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.store.RAMDirectory;

public class IndexMysqlDBStemming {

  public static void main(String[] args) throws Exception {

    // 1. Create Index From Database
    Class.forName("com.mysql.jdbc.Driver").newInstance();
    Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/db_haiquran", "root", "");

    IndonesianAnalyzer analyzer = new IndonesianAnalyzer(Version.LUCENE_42);
    //StandardAnalyzer analyzer = new StandardAnalyzer(Version.LUCENE_42);
    QueryParser parser = new QueryParser(Version.LUCENE_42, "result", analyzer);

    Directory INDEX_DIR = new RAMDirectory();

    IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_42, analyzer);
    IndexWriter writer = new IndexWriter(INDEX_DIR, config);

    String query = "SELECT * FROM ayat";
    java.sql.Statement statement = connection.createStatement();
    ResultSet result = statement.executeQuery(query);

    while (result.next()) {
        Document document = new Document();
        document.add(new Field("NO_INDEX_AYAT", result.getString("NO_INDEX_AYAT"), Field.Store.YES, Field.Index.NOT_ANALYZED));
        document.add(new Field("NO_SURAT", result.getString("NO_SURAT"), Field.Store.YES, Field.Index.NOT_ANALYZED));
        document.add(new Field("NO_AYAT", result.getString("NO_AYAT"), Field.Store.YES, Field.Index.NOT_ANALYZED));
        document.add(new Field("TEXT_INDO", result.getString("TEXT_INDO"), Field.Store.YES, Field.Index.ANALYZED));
        document.add(new Field("TEXT_ARAB", result.getString("TEXT_ARAB"), Field.Store.YES, Field.Index.NOT_ANALYZED));
        writer.updateDocument(new Term("NO_INDEX_AYAT", result.getString("NO_INDEX_AYAT")), document);

    }

    writer.close();


    // 2. Query
    System.out.println("Enter your search keyword in here : ");
    BufferedReader bufferRead = new BufferedReader(new InputStreamReader(System.in));
    String s = bufferRead.readLine();
    String querystr = args.length > 0 ? args[0] :s;

    try {
        System.out.println(parser.parse(querystr)+"\n"); //amenit
        System.out.println();

    } catch (ParseException ex) {
        // Exception
    }

    Query q = new QueryParser(Version.LUCENE_42, "TEXT_INDO", analyzer).parse(querystr);

    // 3. Search

    int hitsPerPage = 10;
    IndexReader reader = DirectoryReader.open(INDEX_DIR);
    IndexSearcher searcher = new IndexSearcher(reader);
    TopScoreDocCollector collector = TopScoreDocCollector.create(hitsPerPage, true);
    searcher.search(q, collector);
    ScoreDoc[] hits = collector.topDocs().scoreDocs;

    // 4. Display results

    System.out.println("Found : " + hits.length + " hits.");

    System.out.println("No" + " ID " + "\t" + " Surat " + "\t" + " No Ayat " + "\t" + " Terjemahan Ayat " + "\t" + " Teks Arab ");

    for (int i=0; i<hits.length; i++) {
       int docID = hits[i].doc;
       Document d = searcher.doc(docID);

       System.out.println((i+1) + ". " + d.get("NO_INDEX_AYAT") + "\t" + d.get("NO_SURAT") + "\t" + d.get("NO_AYAT")+ 
               "\t" + d.get("TEXT_INDO") + "\t" + d.get("TEXT_ARAB"));

    }

    reader.close();        
  }
}

How can I display the results of the calculation using tf-idf and cosine similarity?

如何使用 tf-idf 和余弦相似度显示计算结果？

采纳答案by femtoRgon

Unless there is something I'm missing, you're already done. Well done!

除非我遗漏了什么，否则你已经完成了。做得好！

The similarity algorithm being used by default is the DefaultSimilarity, but most of the documentation (and logic) you'll find in it's base class TFIDFSimilarity.

默认情况下使用的相似性算法是DefaultSimilarity，但您会在它的基类TFIDFSimilarity 中找到大部分文档（和逻辑）。

And TFIDFSimilarity is indeed an implementation of a TF-IDF and Cosine similarity scoring model.

而 TFIDSimilarity 确实是一个 TF-IDF 和 Cosine 相似度评分模型的实现。