Package it.unimi.di.big.mg4j.search.score

Class CountScorer

java.lang.Object

it.unimi.di.big.mg4j.search.score.AbstractScorer

it.unimi.di.big.mg4j.search.score.AbstractWeightedScorer

it.unimi.di.big.mg4j.search.score.CountScorer

All Implemented Interfaces:

DelegatingScorer, Scorer, FlyweightPrototype<Scorer>

public class CountScorer
extends AbstractWeightedScorer
implements DelegatingScorer

A trivial scorer that computes the score by adding the counts (the number of occurrences within the current document) of each term multiplied by the weight of the relative index. Mainly useful for debugging and testing purposes.

This class uses a CounterCollectionVisitor and related classes to take into consideration only terms that are actually involved in the current document.

Author:

Mauro Mereu, Sebastiano Vigna

Field Summary

Fields

Modifier and Type	Field	Description
protected double[]	indexNumber2Weight	An array parallel to TermCollectionVisitor.indices() containing the current corresponding values in AbstractWeightedScorer.index2Weight; it is set up by wrap(DocumentIterator).

Fields inherited from class it.unimi.di.big.mg4j.search.score.AbstractWeightedScorer

index2Weight

Fields inherited from class it.unimi.di.big.mg4j.search.score.AbstractScorer

documentIterator, indexIterator

Constructor Summary

Constructors

Constructor	Description
CountScorer()

Method Summary

Modifier and Type	Method	Description
CountScorer	copy()
double	score()	Computes a score by calling Scorer.score(Index) for each index in the current document iterator, and adding the weighted results.
double	score(Index index)	Returns a score for the current document of the last document iterator given to Scorer.wrap(DocumentIterator), but considering only a given index (optional operation).
boolean	usesIntervals()	Whether this scorer uses intervals.
void	wrap(DocumentIterator d)	Wraps the given document iterator.

Methods inherited from class it.unimi.di.big.mg4j.search.score.AbstractWeightedScorer

getWeights, setWeights

Methods inherited from class it.unimi.di.big.mg4j.search.score.AbstractScorer

nextDocument

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface it.unimi.di.big.mg4j.search.score.Scorer

getWeights, nextDocument, setWeights

Field Detail

indexNumber2Weight

protected double[] indexNumber2Weight

An array parallel to TermCollectionVisitor.indices() containing the current corresponding values in AbstractWeightedScorer.index2Weight; it is set up by wrap(DocumentIterator).

Constructor Detail

CountScorer

public CountScorer()

Method Detail

score

public double score()
             throws IOException

Description copied from class: AbstractWeightedScorer

Computes a score by calling Scorer.score(Index) for each index in the current document iterator, and adding the weighted results.

Specified by:

score in interface Scorer

Overrides:

score in class AbstractWeightedScorer

Returns:

the combined weighted score.

Throws:

IOException

score

public double score(Index index)

Description copied from interface: Scorer

Returns a score for the current document of the last document iterator given to Scorer.wrap(DocumentIterator), but considering only a given index (optional operation).

Specified by:

score in interface Scorer

Parameters:

index - the only index to be considered.

Returns:

the score.

wrap

public void wrap(DocumentIterator d)
          throws IOException

Description copied from class: AbstractScorer

Wraps the given document iterator.

This method records internally the provided iterator.

Specified by:

wrap in interface Scorer

Overrides:

wrap in class AbstractWeightedScorer

Parameters:

d - the document iterator that will be used in subsequent calls to Scorer.score() and Scorer.score(Index).

Throws:

IOException

copy

public CountScorer copy()

Specified by:

copy in interface FlyweightPrototype<Scorer>

Specified by:

copy in interface Scorer

usesIntervals

public boolean usesIntervals()

Description copied from interface: Scorer

Whether this scorer uses intervals.

This method is essential when aggregating scorers, because if several scores need intervals, a CachingDocumentIterator will be necessary.

Specified by:

usesIntervals in interface Scorer

Returns:

true if this scorer uses intervals.