org.lenskit.bias

Class UserItemBiasModel

java.lang.Object

org.lenskit.bias.UserItemBiasModel

All Implemented Interfaces:

Serializable, BiasModel

Direct Known Subclasses:

ItemBiasModel, UserBiasModel

@Shareable
 @Immutable
 @DefaultProvider(value=UserItemAverageRatingBiasModelProvider.class)
public class UserItemBiasModel
extends Object
implements BiasModel, Serializable

Bias model that provides global, user, and item biases. The user and item biases are precomputed and are not refreshed based on user data added since the model build.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
UserItemBiasModel(double global, Long2DoubleMap users, Long2DoubleMap items) Construct a new user 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(LongSet items) Get a set of item biases.
double	getUserBias(long user) Get the user bias.
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

UserItemBiasModel

public UserItemBiasModel(double global,
                         Long2DoubleMap users,
                         Long2DoubleMap items)

Construct a new user bias model.

Parameters:

global - The global bias.

users - The user biases.

items - The item biases.

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.

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 Long2DoubleFunction.defaultReturnValue() will be 0.

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.

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 Long2DoubleFunction.defaultReturnValue() will be 0.