Examples of it.unimi.dsi.mg4j.search.IntervalIterator

it.unimi.dsi.mg4j.search.IntervalIterator
An iterator over {@linkplain Interval intervals}. Apart for the usual methods of a (type-specific) iterator, it has a special (optional) {@link #reset()} method that allows one to resetthe iterator: the exact meaning of this operation is decided by the implementing classes. Typically, after a {@link #reset()}, one can iterate over a new sequence.
Warning: from MG4J 1.2, most methods throw an {@link IOException}(such exceptions used to be catched and wrapped into a {@link RuntimeException}).
This interface also specifies a method {@link #extent()} returninga positive integer that is supposed to approximate the minimum possible length of an interval returned by this iterator. This method returns -1 if this extent cannot be computed.

        secondIterator = !textTerm?secondIndexReader.documents(i):secondIndexReader.documents(firstIndex.termMap.list().get(i));        
        while(firstIterator.hasNext()){
          firstIterator.next();
          secondIterator.next();  
          /** Compare position IntIterator*/
          IntervalIterator firstIntervalIt = firstIterator.intervalIterator(firstIndex);
          IntervalIterator secondIntervalIt = secondIterator.intervalIterator(secondIndex);
          while(firstIntervalIt.hasNext()){              
            Interval firstIntv = firstIntervalIt.nextInterval();
            Interval secondIntv = secondIntervalIt.nextInterval();
            
            System.out.println("left:" +  firstIntv.left + "   " + "right:" + firstIntv.right);
            Assert.assertEquals(firstIntv.left,secondIntv.left);
            Assert.assertEquals(firstIntv.right,secondIntv.right);
          }

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 * extremely frequent terms, with no perceivable effect on the score itself. 
 */
public class VignaScorer extends AbstractWeightedScorer implements DelegatingScorer {
  
  public double score( final Index index ) throws IOException {
    final IntervalIterator it = documentIterator.intervalIterator( index );
    if ( it == IntervalIterators.TRUE || it == IntervalIterators.FALSE ) return 0;
    double score = 0, residual = 1, t;
    int extent = it.extent(), length;
    Interval interval;
    while ( ( interval = it.nextInterval() ) != null ) {
      length = interval.length();
      t = residual * Math.min( (double)extent / length, 1 ) / 2;
      residual -= t;
      score += t;
      if ( score > .99 ) return 1;

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    scorer.setWeights( index2Weight );
    return scorer;
  }
  
  public double score( final Index index ) throws IOException {
    final IntervalIterator it = documentIterator.intervalIterator( index );
    if ( it == IntervalIterators.TRUE || it == IntervalIterators.FALSE ) return 0;
    double result = 0;
    int lt, count = 0;
    Interval interval;
    while ( ( interval = it.nextInterval() ) != null ) {
      count++;
      lt = interval.length();
      if ( lt < h ) result += 1;
      else result += Math.pow( h / (double) lt, alpha );
    }

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   * @return <code>index2Interval</code>.
   * @throws IOException 
   */
  public Reference2ObjectMap<Index,SelectedInterval[]> select( final DocumentIterator documentIterator, final Reference2ObjectMap<Index,SelectedInterval[]> index2Interval ) throws IOException {
    index2Interval.clear();
    IntervalIterator intervalIterator;
    for( Index index : documentIterator.indices() ) {
      if ( index.hasPositions ) {
        intervalIterator = documentIterator.intervalIterator( index );
        if ( intervalIterator == IntervalIterators.TRUE ) index2Interval.put( index, SelectedInterval.TRUE_ARRAY );
        else index2Interval.put( index, select( documentIterator.intervalIterator( index ) ) );

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    Query query = simpleParser.parse( "(a|b|d)<(a|b|d)" );
    DocumentIteratorBuilderVisitor documentIteratorBuilderVisitor = new DocumentIteratorBuilderVisitor( null, index, Integer.MAX_VALUE );
    DocumentIterator documentIterator = query.accept( documentIteratorBuilderVisitor );
    documentIterator.nextDocument();
    IntervalIterator intervalIterator = documentIterator.intervalIterator();
    assertEquals( Interval.valueOf( 0, 1 ), intervalIterator.nextInterval() );
    assertEquals( Interval.valueOf( 1, 2 ), intervalIterator.nextInterval() );
    assertEquals( Interval.valueOf( 2, 4 ), intervalIterator.nextInterval() );
    assertFalse( intervalIterator.hasNext() );
    documentIterator.dispose();
  }

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Related Classes of it.unimi.dsi.mg4j.search.IntervalIterator

it.unimi.dsi.mg4j.query.IntervalSelector

it.unimi.dsi.mg4j.search.OrderedAndDocumentIteratorTest

it.unimi.dsi.mg4j.search.score.ClarkeCormackScorer

it.unimi.dsi.mg4j.search.score.VignaScorer

it.unimi.dsi.mg4j.test.RemoteIndexIteratorTest

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