PIP (CF4J 2.3.0 API Documentation)

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 Description

PIP()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	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