es.uam.eps.ir.ranksys.diversity.sales.metrics

Class GiniIndex<U,I>

java.lang.Object

es.uam.eps.ir.ranksys.metrics.AbstractSystemMetric<U,I>

es.uam.eps.ir.ranksys.diversity.sales.metrics.AbstractSalesDiversityMetric<U,I>

es.uam.eps.ir.ranksys.diversity.sales.metrics.GiniIndex<U,I>

Type Parameters:

U - type of the users

I - type of the items

All Implemented Interfaces:

SystemMetric<U,I>

public class GiniIndex<U,I>
extends AbstractSalesDiversityMetric<U,I>

Gini index sales diversity metric. S. Vargas. Novelty and diversity evaluation and enhancement in Recommender Systems. PhD Thesis.

Author:

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

Field Summary

Fields inherited from class es.uam.eps.ir.ranksys.diversity.sales.metrics.AbstractSalesDiversityMetric

cutoff, freeNorm, itemCount, itemWeight, numUsers

Constructor Summary

Constructors

Constructor and Description
GiniIndex(int cutoff, int numItems) Constructor.

Method Summary

Modifier and Type	Method and Description
double	evaluate() Evaluates the metric for the recommendations added so far.
protected double	nov(I i) Returns the sales novelty of an item.

Methods inherited from class es.uam.eps.ir.ranksys.diversity.sales.metrics.AbstractSalesDiversityMetric

add, combine, reset

Methods inherited from class java.lang.Object

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

Constructor Detail

GiniIndex

public GiniIndex(int cutoff,
                 int numItems)

Constructor.

Parameters:

cutoff - maximum length of the recommendation lists that is evaluated

numItems - total number of items in the catalog

Method Detail

evaluate

public double evaluate()

Evaluates the metric for the recommendations added so far.

Specified by:

evaluate in interface SystemMetric<U,I>

Overrides:

evaluate in class AbstractSalesDiversityMetric<U,I>

Returns:

result of the metric for the recommendations previously added

nov

protected double nov(I i)

Returns the sales novelty of an item.

Specified by:

nov in class AbstractSalesDiversityMetric<U,I>

Parameters:

i - item

Returns:

the sales novelty of the item