org.lenskit.bias

Class LiveUserItemBiasModel

java.lang.Object

org.lenskit.bias.LiveUserItemBiasModel

All Implemented Interfaces:

BiasModel

public final class LiveUserItemBiasModel
extends java.lang.Object
implements BiasModel

Bias model that provides global, user, and item biases. The global and item biases are precomputed and are not refreshed based on user data added since the model build, but the user bias (mean rating from the rating DAO) is recomputed live based on a RatingVectorPDAO.

Note: The getUserBiases() method will always return an empty map.

Constructor Summary

Constructors

Constructor and Description
LiveUserItemBiasModel(ItemBiasModel base, RatingVectorPDAO dao) Construct a new bias model.

Method Summary

Modifier and Type	Method and Description
double	getIntercept() Get the global bias (intercept).
double	getItemBias(long item) Get the item bias.
Long2DoubleMap	getItemBiases() Get the map of all known item biases.
Long2DoubleMap	getItemBiases(LongSet items) Get a set of item biases.
double	getUserBias(long user) Get the user bias.
Long2DoubleMap	getUserBiases() Return an empty map.
Long2DoubleMap	getUserBiases(LongSet users) Get a set of user biases.

Methods inherited from class java.lang.Object

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

Constructor Detail

LiveUserItemBiasModel

@Inject
public LiveUserItemBiasModel(ItemBiasModel base,
                                     RatingVectorPDAO dao)

Construct a new bias model.

Parameters:

base - An item bias model to use as the base model.

dao - The rating vector DAO to fetch user data.

Method Detail

getIntercept

public double getIntercept()

Description copied from interface: BiasModel

Get the global bias (intercept).

Specified by:

getIntercept in interface BiasModel

Returns:

The global bias.

getUserBias

public double getUserBias(long user)

Description copied from interface: BiasModel

Get the user bias.

Specified by:

getUserBias in interface BiasModel

Parameters:

user - The user ID.

Returns:

The bias for the specified user, or 0 if the user’s bias is unknown.

getItemBias

public double getItemBias(long item)

Description copied from interface: BiasModel

Get the item bias.

Specified by:

getItemBias in interface BiasModel

Parameters:

item - The item ID.

Returns:

The bias for the specified ite, or 0 if the item’s bias is unknown.

getUserBiases

public Long2DoubleMap getUserBiases(LongSet users)

Description copied from interface: BiasModel

Get a set of user biases.

Specified by:

getUserBiases in interface BiasModel

Parameters:

users - The users whose biases are to be returned.

Returns:

A mapping from user IDs to biases. It is not guaranteed to contain all user IDs in its key set, but its Long2DoubleMap.defaultReturnValue() will be 0.

getItemBiases

public Long2DoubleMap getItemBiases(LongSet items)

Description copied from interface: BiasModel

Get a set of item biases.

Specified by:

getItemBiases in interface BiasModel

Parameters:

items - The items whose biases are to be returned.

Returns:

A mapping from item IDs to biases. It is not guaranteed to contain all item IDs in its key set, but its Long2DoubleMap.defaultReturnValue() will be 0.

getUserBiases

public Long2DoubleMap getUserBiases()

Return an empty map. This may make this bias model unsuitable in some applications.

Specified by:

getUserBiases in interface BiasModel

Returns:

An empty map.

getItemBiases

public Long2DoubleMap getItemBiases()

Description copied from interface: BiasModel

Get the map of all known item biases.

Specified by:

getItemBiases in interface BiasModel

Returns:

The set of all item biases.