org.grouplens.lenskit.knn.item.model

Class SimilarityMatrixModel

java.lang.Object

org.grouplens.lenskit.knn.item.model.SimilarityMatrixModel

All Implemented Interfaces:

Serializable, ItemItemModel

@DefaultProvider(value=ItemItemModelBuilder.class)
 @Shareable
public class SimilarityMatrixModel
extends Object
implements Serializable, ItemItemModel

Item-item similarity model using an in-memory similarity matrix.

These similarities are post-normalization, so code using them should use the same normalizations used by the builder to make use of the similarity scores.

Since:

0.10

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
SimilarityMatrixModel(LongKeyDomain items, List<ImmutableSparseVector> nbrs) Deprecated. This is deprecated for public usage. It is better to use the other constructor.
SimilarityMatrixModel(Map<Long,ImmutableSparseVector> nbrs) Construct a new item-item model.

Method Summary

Modifier and Type	Method and Description
LongSortedSet	getItemUniverse() Get the set of all items in the model.
SparseVector	getNeighbors(long item) Get the neighbors of an item scored by similarity.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

SimilarityMatrixModel

@Deprecated
public SimilarityMatrixModel(LongKeyDomain items,
                                         List<ImmutableSparseVector> nbrs)

Deprecated. This is deprecated for public usage. It is better to use the other constructor.

Construct a new item-item model.

Parameters:

items - The item domain.

nbrs - The item neighborhoods.

SimilarityMatrixModel

public SimilarityMatrixModel(Map<Long,ImmutableSparseVector> nbrs)

Construct a new item-item model.

Parameters:

nbrs - The item neighborhoods. The item neighborhood lists are not copied.

Method Detail

getItemUniverse

public LongSortedSet getItemUniverse()

Description copied from interface: ItemItemModel

Get the set of all items in the model.

Specified by:

getItemUniverse in interface ItemItemModel

Returns:

The set of item IDs for all items in the model.

getNeighbors

@Nonnull
public SparseVector getNeighbors(long item)

Description copied from interface: ItemItemModel

Get the neighbors of an item scored by similarity. This is the corresponding row of the item-item similarity matrix (see org.grouplens.lenskit.knn.item).

Specified by:

getNeighbors in interface ItemItemModel

Parameters:

item - The item to get the neighborhood for.

Returns:

The row of the similarity matrix. If the item is unknown, an empty vector is returned.

toString

public String toString()

Overrides:

toString in class Object