es.upm.etsisi.cf4j.recommender.knn.itemSimilarityMetric

Class PIP

java.lang.Object

es.upm.etsisi.cf4j.recommender.knn.itemSimilarityMetric.ItemSimilarityMetric

es.upm.etsisi.cf4j.recommender.knn.itemSimilarityMetric.PIP

All Implemented Interfaces:

Partible<Item>

public class PIP
extends ItemSimilarityMetric

This class implements the PIP CF similarity metric for the items. The similarity metric is described here: Ahn, H. J. (2008). A new similarity measure for collaborative filtering o alleviate the new user cold-starting problem, Information Sciences, 178, 37??51.

Field Summary

Fields inherited from class es.upm.etsisi.cf4j.recommender.knn.itemSimilarityMetric.ItemSimilarityMetric

datamodel, similarities

Constructor Summary

Constructors

Constructor and Description
PIP()

Method Summary

Modifier and Type	Method and Description
void	beforeRun() Is executed once before execute the method 'exec'.
double	similarity(Item item, Item otherItem) This method must returns the similarity between two items.

Methods inherited from class es.upm.etsisi.cf4j.recommender.knn.itemSimilarityMetric.ItemSimilarityMetric

afterRun, getSimilarities, run, setDatamodel, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

PIP

public PIP()

Method Detail

beforeRun

public void beforeRun()

Description copied from interface: Partible

Is executed once before execute the method 'exec'. It can be used to initialize resources.

Specified by:

beforeRun in interface Partible<Item>

Overrides:

beforeRun in class ItemSimilarityMetric

similarity

public double similarity(Item item,
                         Item otherItem)

Description copied from class: ItemSimilarityMetric

This method must returns the similarity between two items.

If two items do not have a similarity value, the method must return Double.NEGATIVE_INFINITY.

The value returned by this method should be higher the greater the similarity between items.

Specified by:

similarity in class ItemSimilarityMetric

Parameters:

item - An item

otherItem - Other item

Returns:

Similarity between item and otherItem