org.grouplens.lenskit.data.snapshot

Class PackedPreferenceSnapshot

java.lang.Object

org.grouplens.lenskit.data.snapshot.AbstractPreferenceSnapshot

org.grouplens.lenskit.data.snapshot.PackedPreferenceSnapshot

All Implemented Interfaces:

Closeable, AutoCloseable, PreferenceSnapshot

@DefaultProvider(value=PackedPreferenceSnapshotBuilder.class)
 @Shareable
public class PackedPreferenceSnapshot
extends AbstractPreferenceSnapshot

An in-memory snapshot of rating data stored in packed arrays.

Note that PackedPreferenceSnapshot is annotated with @Built but is declared as ephemeral. Because of this, the snapshot will not be included in built RecommenderEngines, so it is not Serializable.

Field Summary

Fields inherited from class org.grouplens.lenskit.data.snapshot.AbstractPreferenceSnapshot

cache

Method Summary

Modifier and Type	Method and Description
void	close() Close the build context.
LongCollection	getItemIds() Get the set of item IDs in the snapshot.
FastCollection<IndexedPreference>	getRatings() Get the collection of ratings in the snapshot.
LongCollection	getUserIds() Get the set of user IDs in the snapshot.
FastCollection<IndexedPreference>	getUserRatings(long userId) Get the ratings for a particular user.
IdIndexMapping	itemIndex() Get the item ID index.
static PreferenceSnapshot	pack(EventDAO dao)
IdIndexMapping	userIndex() Get the user ID index.

Methods inherited from class org.grouplens.lenskit.data.snapshot.AbstractPreferenceSnapshot

userRatingVector

Methods inherited from class java.lang.Object

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

Method Detail

pack

public static PreferenceSnapshot pack(EventDAO dao)

getUserIds

public LongCollection getUserIds()

Description copied from interface: PreferenceSnapshot

Get the set of user IDs in the snapshot.

Returns:

A set of all known user IDs.

getItemIds

public LongCollection getItemIds()

Description copied from interface: PreferenceSnapshot

Get the set of item IDs in the snapshot.

Returns:

A set of all known item IDs.

userIndex

public IdIndexMapping userIndex()

Description copied from interface: PreferenceSnapshot

Get the user ID index.

Returns:

The index mapping between user IDs and user indices.

itemIndex

public IdIndexMapping itemIndex()

Description copied from interface: PreferenceSnapshot

Get the item ID index.

Returns:

The index mapping between user IDs and user indices.

getRatings

public FastCollection<IndexedPreference> getRatings()

Description copied from interface: PreferenceSnapshot

Get the collection of ratings in the snapshot. The ratings are returned in an undetermined order. It is guaranteed that no duplicate ratings appear - each (user,item) pair is rated at most once. Each preference's index is also in the range [0,len), where len is the size of this collection.

Modifying the returned indexed preferences will not modify the underlying snapshot.

Returns:

All ratings in the system.

getUserRatings

public FastCollection<IndexedPreference> getUserRatings(long userId)

Description copied from interface: PreferenceSnapshot

Get the ratings for a particular user. It is guaranteed that no duplicate ratings appear - each (user,item) pair is rated at most once.

Modifying the returned indexed preferences will not modify the underlying snapshot.

Parameters:

userId - The user's ID.

Returns:

The user's ratings, or an empty collection if the user is unknown.

close

public void close()

Description copied from interface: PreferenceSnapshot

Close the build context. This overrides Closeable.close() to drop the exception that can be thrown.

After the build context has been closed, all methods are allowed to fail. Objects returned from those methods, however, should continue to be valid.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface PreferenceSnapshot

Overrides:

close in class AbstractPreferenceSnapshot