public void seek(TermEnum terms) throws IOException {
      original.seek(terms);

      docFreq = terms.docFreq();
      pointer = -1;

      if (docFreq > postingMaps.length) { // grow postingsMap
        PostingMap[] newMap = new PostingMap[docFreq];
        System.arraycopy(postingMaps, 0, newMap, 0, postingMaps.length);
        for (int i = postingMaps.length; i < docFreq; i++) {
          newMap[i] = new PostingMap();
        }
        postingMaps = newMap;
      }

      out.reset();

      int i = 0;
      while (original.next()) {
        PostingMap map = postingMaps[i++];
        map.newDoc = oldToNew[original.doc()]; // remap the newDoc id
        map.offset = out.getFilePointer(); // save pointer to buffer

        final int tf = original.freq(); // buffer tf & positions
        out.writeVInt(tf);
        int prevPosition = 0;
        for (int j = tf; j > 0; j--) { // delta encode positions
          int p = original.nextPosition();
          out.writeVInt(p - prevPosition);
          prevPosition = p;
        }
      }
      out.flush();
      docFreq = i; // allow for deletions

      Arrays.sort(postingMaps, 0, docFreq); // resort by mapped doc ids
      // HeapSorter.sort(postingMaps,docFreq); // TODO MC - due to the lack of space

      // NOTE: this might be substantially faster if RAMInputStream were public
      // and supported a reset() operation.
      in = tempDir.openInput(TEMP_FILE);
    }
Beispiel #2
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  public static void main(String[] args) throws Exception {
    // the IndexReader object is the main handle that will give you
    // all the documents, terms and inverted index
    IndexReader r = IndexReader.open(FSDirectory.open(new File("index")));

    // You can figure out the number of documents using the maxDoc() function
    System.out.println("The number of documents in this index is: " + r.maxDoc());

    int i = 0;
    // You can find out all the terms that have been indexed using the terms() function
    TermEnum t = r.terms();
    while (t.next()) {
      // Since there are so many terms, let us try printing only term #100000-#100010
      if (i > 100000) System.out.println("[" + i + "] " + t.term().text());
      if (++i > 100010) break;
    }

    // You can create your own query terms by calling the Term constructor, with the field
    // 'contents'
    // In the following example, the query term is 'brute'
    Term te = new Term("contents", "brute");

    // You can also quickly find out the number of documents that have term t
    System.out.println("Number of documents with the word 'brute' is: " + r.docFreq(te));

    // You can use the inverted index to find out all the documents that contain the term 'brute'
    //  by using the termDocs function
    TermDocs td = r.termDocs(te);
    while (td.next()) {
      System.out.println(
          "Document number ["
              + td.doc()
              + "] contains the term 'brute' "
              + td.freq()
              + " time(s).");
    }

    // You can find the URL of the a specific document number using the document() function
    // For example, the URL for document number 14191 is:
    Document d = r.document(14191);
    String url =
        d.getFieldable("path")
            .stringValue(); // the 'path' field of the Document object holds the URL
    System.out.println(url.replace("%%", "/"));

    // -------- Now let us use all of the functions above to make something useful --------
    // The following bit of code is a worked out example of how to get a bunch of documents
    // in response to a query and show them (without ranking them according to TF/IDF)
    Scanner sc = new Scanner(System.in);
    String str = "";
    System.out.print("query> ");
    while (!(str = sc.nextLine()).equals("quit")) {
      String[] terms = str.split("\\s+");
      for (String word : terms) {
        Term term = new Term("contents", word);
        TermDocs tdocs = r.termDocs(term);
        while (tdocs.next()) {
          String d_url =
              r.document(tdocs.doc()).getFieldable("path").stringValue().replace("%%", "/");
          System.out.println("[" + tdocs.doc() + "] " + d_url);
        }
      }
      System.out.print("query> ");
    }
  }