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

Class AbstractWeightedScorer

java.lang.Object

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

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

All Implemented Interfaces:

Scorer, FlyweightPrototype<Scorer>

Direct Known Subclasses:

BM25FScorer, BM25Scorer, ClarkeCormackScorer, CountScorer, TfIdfScorer, VignaScorer

public abstract class AbstractWeightedScorer
extends AbstractScorer

An abstract subsclass of AbstractScorer providing internal storage and copy of the weight map and a default implementation of score().

Warning: implementing subclasses must implement Scorer.copy() so that the state of the weight map is replicated, too.

Field Summary

Fields

Modifier and Type	Field	Description
protected Reference2DoubleOpenHashMap<Index>	index2Weight	A map associating a weight with each index.

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

documentIterator, indexIterator

Constructor Summary

Constructors

Constructor	Description
AbstractWeightedScorer()

Method Summary

Modifier and Type	Method	Description
Reference2DoubleMap<Index>	getWeights()	Returns an empty map.
double	score()	Computes a score by calling Scorer.score(Index) for each index in the current document iterator, and adding the weighted results.
boolean	setWeights(Reference2DoubleMap<Index> index2Weight)	Copies the argument internally, rescaling weights so they sum up to one.
void	wrap(DocumentIterator documentIterator)	Wraps the given document iterator.

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

copy, score, usesIntervals

Field Detail

index2Weight

protected Reference2DoubleOpenHashMap<Index> index2Weight

A map associating a weight with each index.

Constructor Detail

AbstractWeightedScorer

public AbstractWeightedScorer()

Method Detail

setWeights

public boolean setWeights(Reference2DoubleMap<Index> index2Weight)

Copies the argument internally, rescaling weights so they sum up to one.

Specified by:

setWeights in interface Scorer

Overrides:

setWeights in class AbstractScorer

Parameters:

index2Weight - the new map from indices to weights.

Returns:

true.

getWeights

public final Reference2DoubleMap<Index> getWeights()

Description copied from class: AbstractScorer

Returns an empty map.

Specified by:

getWeights in interface Scorer

Overrides:

getWeights in class AbstractScorer

Returns:

a copy of the weight map of this scorer.

score

public double score()
             throws IOException

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

Returns:

the combined weighted score.

Throws:

IOException

wrap

public void wrap(DocumentIterator documentIterator)
          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 AbstractScorer

Parameters:

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

Throws:

IOException