org.grouplens.lenskit.mf.svd

Class MFModel

java.lang.Object

org.grouplens.lenskit.mf.svd.MFModel

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

FunkSVDModel

public class MFModel
extends Object
implements Serializable

Common model for matrix factorization (SVD) recommendation.

Since:

2.1

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected int	featureCount
protected int	itemCount
protected IdIndexMapping	itemIndex
protected mikera.matrixx.impl.ImmutableMatrix	itemMatrix
protected int	userCount
protected IdIndexMapping	userIndex
protected mikera.matrixx.impl.ImmutableMatrix	userMatrix

Constructor Summary

Constructors

Constructor and Description
MFModel(mikera.matrixx.impl.ImmutableMatrix umat, mikera.matrixx.impl.ImmutableMatrix imat, IdIndexMapping uidx, IdIndexMapping iidx) Construct a matrix factorization model.

Method Summary

Modifier and Type	Method and Description
int	getFeatureCount() Get the model's feature count.
int	getItemCount() The number of items.
double	getItemFeature(long iid, int feature) Get a particular feature value for an item.
IdIndexMapping	getItemIndex() The item index mapping.
mikera.matrixx.IMatrix	getItemMatrix() Get the item matrix.
mikera.vectorz.AVector	getItemVector(long item)
int	getUserCount() The number of users.
double	getUserFeature(long uid, int feature) Get a particular feature value for an user.
IdIndexMapping	getUserIndex() The user index mapping.
mikera.matrixx.IMatrix	getUserMatrix() Get the user matrix.
mikera.vectorz.AVector	getUserVector(long user)
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

featureCount

protected int featureCount

userCount

protected int userCount

itemCount

protected int itemCount

userMatrix

protected mikera.matrixx.impl.ImmutableMatrix userMatrix

itemMatrix

protected mikera.matrixx.impl.ImmutableMatrix itemMatrix

userIndex

protected IdIndexMapping userIndex

itemIndex

protected IdIndexMapping itemIndex

Constructor Detail

MFModel

public MFModel(mikera.matrixx.impl.ImmutableMatrix umat,
               mikera.matrixx.impl.ImmutableMatrix imat,
               IdIndexMapping uidx,
               IdIndexMapping iidx)

Construct a matrix factorization model. The matrices are not copied, so the caller should make sure they won't be modified by anyone else.

Parameters:

umat - The user feature matrix (users x features).

imat - The item feature matrix (items x features).

uidx - The user index mapping.

iidx - The item index mapping.

Method Detail

getFeatureCount

public int getFeatureCount()

Get the model's feature count.

Returns:

The model's feature count.

getUserCount

public int getUserCount()

The number of users.

getItemCount

public int getItemCount()

The number of items.

getItemIndex

public IdIndexMapping getItemIndex()

The item index mapping.

getUserIndex

public IdIndexMapping getUserIndex()

The user index mapping.

getUserMatrix

public mikera.matrixx.IMatrix getUserMatrix()

Get the user matrix.

Returns:

The user matrix (users x features).

getItemMatrix

public mikera.matrixx.IMatrix getItemMatrix()

Get the item matrix.

Returns:

The item matrix (items x features).

getUserVector

@Nullable
public mikera.vectorz.AVector getUserVector(long user)

getItemVector

@Nullable
public mikera.vectorz.AVector getItemVector(long item)

getUserFeature

public double getUserFeature(long uid,
                             int feature)

Get a particular feature value for an user.

Parameters:

uid - The item ID.

feature - The feature.

Returns:

The user-feature value, or 0 if the user was not in the training set.

getItemFeature

public double getItemFeature(long iid,
                             int feature)

Get a particular feature value for an item.

Parameters:

iid - The item ID.

feature - The feature.

Returns:

The item-feature value, or 0 if the item was not in the training set.

toString

public String toString()

Overrides:

toString in class Object