es.uam.eps.ir.ranksys.novdiv.reranking

Class GreedyReranker<U,I>

java.lang.Object

es.uam.eps.ir.ranksys.novdiv.reranking.PermutationReranker<U,I>

es.uam.eps.ir.ranksys.novdiv.reranking.GreedyReranker<U,I>

Type Parameters:

U - type of the users

I - type of the items

All Implemented Interfaces:

Reranker<U,I>

Direct Known Subclasses:

LambdaReranker, PM

public abstract class GreedyReranker<U,I>
extends PermutationReranker<U,I>

Greedy re-ranking. Greedily selects items from an input recommendation according to a selection criterion that is updated after a selection. It requires a nested GreedyReranker.GreedyUserReranker.

Author:

Saúl Vargas (saul.vargas@uam.es), Pablo Castells (pablo.castells@uam.es)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	GreedyReranker.GreedyUserReranker<U,I> Re-ranker of a single recommendation.

Field Summary

Fields

Modifier and Type	Field and Description
protected int	cutoff Cut-off of the re-ranking.

Constructor Summary

Constructors

Constructor and Description
GreedyReranker(int cutoff) Constructor.

Method Summary

Modifier and Type	Method and Description
protected abstract GreedyReranker.GreedyUserReranker<U,I>	getUserReranker(Recommendation<U,I> recommendation, int maxLength) Returns an instance of GreedyReranker.GreedyUserReranker that does the greedy selection.
int[]	rerankPermutation(Recommendation<U,I> recommendation, int maxLength) Returns the permutation that is applied to the input recommendation to generate the re-ranked recommendation.

Methods inherited from class es.uam.eps.ir.ranksys.novdiv.reranking.PermutationReranker

getBasePerm, permuteRecommendation, rerankRecommendation

Methods inherited from class java.lang.Object

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

Field Detail

cutoff

protected final int cutoff

Cut-off of the re-ranking.

Constructor Detail

GreedyReranker

public GreedyReranker(int cutoff)

Constructor.

Parameters:

cutoff - how many items are re-ranked by the greedy selection.

Method Detail

rerankPermutation

public int[] rerankPermutation(Recommendation<U,I> recommendation,
                               int maxLength)

Returns the permutation that is applied to the input recommendation to generate the re-ranked recommendation.

Specified by:

rerankPermutation in class PermutationReranker<U,I>

Parameters:

recommendation - input recommendation

maxLength - maximum length of the permutation

Returns:

permutation that encodes the re-ranking

getUserReranker

protected abstract GreedyReranker.GreedyUserReranker<U,I> getUserReranker(Recommendation<U,I> recommendation,
                                                                          int maxLength)

Returns an instance of GreedyReranker.GreedyUserReranker that does the greedy selection.

Parameters:

recommendation - input recommendation to be re-ranked

maxLength - maximum length of the resulting re-ranked recommendation

Returns:

the GreedyReranker.GreedyUserReranker that does the re-ranking