Recommender (CF4J 2.2.2 API Documentation)

java.lang.Object
- es.upm.etsisi.cf4j.recommender.Recommender

Direct Known Subclasses:

BeMF, BiasedMF, BNMF, CLiMF, DeepMF, HPF, ItemKNN, NCCF, NMF, PMF, SVDPlusPlus, URP, UserKNN
```
public abstract class Recommender
extends Object
```
Abstract class that represents any recommender. To build a new recommender following methods must be implemented:
- fit(): fits the recommender according to an instance of a DataModel.
- predict(userIndex, itemIndex): computes a rating prediction for a given user and item.

Field Summary

Fields
Modifier and Type Field Description

protected DataModel datamodel
DataModel instance used for the Recommender

Constructor Summary

Constructors
Modifier Constructor Description

protected Recommender(DataModel datamodel)
Recommender constructor

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`abstract void`	`fit()`	Estimates model parameters given the hyper-parameters
`DataModel`	`getDataModel()`	Returns the DataModel instance
`abstract double`	`predict(int userIndex, int itemIndex)`	Computes a rating prediction
`double[]`	`predict(TestUser testUser)`	Computes the rating predictions of the TestItems rated by a TestUser

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - datamodel
```
protected DataModel datamodel
```
    DataModel instance used for the Recommender
- Constructor Detail
  - Recommender
```
protected Recommender(DataModel datamodel)
```
    Recommender constructor
    
    Parameters:
    
    datamodel - instance of a DataModel
- Method Detail
  - getDataModel
```
public DataModel getDataModel()
```
    Returns the DataModel instance
    
    Returns:
    
    DataModel instance used by the Recommender
  - fit
```
public abstract void fit()
```
    Estimates model parameters given the hyper-parameters
  - predict
```
public abstract double predict(int userIndex,
                               int itemIndex)
```
    Computes a rating prediction
    
    Parameters:
    
    userIndex - Index of the user in the array of Users of the DataModel instance
    
    itemIndex - Index of the item in the array of Items of the DataModel instance
    
    Returns:
    
    Prediction
  - predict
```
public double[] predict(TestUser testUser)
```
    Computes the rating predictions of the TestItems rated by a TestUser
    
    Parameters:
    
    testUser - TestUser for which to calculate resting predictions
    
    Returns:
    
    Rating prediction for TestItems rated by testUser. Positions of this array overlaps with testItemIndexes returned by testUser.getTestItemAt(pos)