org.grouplens.lenskit.indexes

Class MutableIdIndexMapping

java.lang.Object

org.grouplens.lenskit.indexes.IdIndexMapping

org.grouplens.lenskit.indexes.MutableIdIndexMapping

All Implemented Interfaces:

Serializable

public final class MutableIdIndexMapping
extends IdIndexMapping

Mutable index mapping. Use this when you need to have indexes before you've seen all the IDs.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
MutableIdIndexMapping() Construct a new empty indexer.

Method Summary

Modifier and Type	Method and Description
long	getId(int idx) Get the ID for an index.
LongList	getIdList() Get the list of indexed IDs.
IdIndexMapping	immutableCopy() Make an immutable copy of this index mapping.
int	internId(long id) Get an index for an ID, generating a new one if necessary.
int	size() Get the size of this index.
int	tryGetIndex(long id) Try to get the index for an ID, returning a negative value if it does not exist.

Methods inherited from class org.grouplens.lenskit.indexes.IdIndexMapping

containsId, create, getIndex

Methods inherited from class java.lang.Object

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

Constructor Detail

MutableIdIndexMapping

public MutableIdIndexMapping()

Construct a new empty indexer. The first interned ID will have index 0.

Method Detail

getId

public long getId(int idx)

Description copied from class: IdIndexMapping

Get the ID for an index.

Specified by:

getId in class IdIndexMapping

Parameters:

idx - The index of the ID to retrieve.

Returns:

The ID for the given idx.

getIdList

public LongList getIdList()

Description copied from class: IdIndexMapping

Get the list of indexed IDs.

Specified by:

getIdList in class IdIndexMapping

Returns:

The list of IDs in the index. No ID will appear twice.

tryGetIndex

public int tryGetIndex(long id)

Description copied from class: IdIndexMapping

Try to get the index for an ID, returning a negative value if it does not exist. This method is like IdIndexMapping.getIndex(long), except it returns a negative value instead of throwing an exception if the id does not exist.

Specified by:

tryGetIndex in class IdIndexMapping

Parameters:

id - The ID to look for.

Returns:

The index of the ID, or a negative value if it is not in the index.

size

public int size()

Description copied from class: IdIndexMapping

Get the size of this index.

Specified by:

size in class IdIndexMapping

Returns:

The number of indexed IDs.

internId

public int internId(long id)

Get an index for an ID, generating a new one if necessary.

Parameters:

id - The ID.

Returns:

The index for id. If the ID has already been added to the index, the old index is returned; otherwise, a new index is generated and returned.

immutableCopy

public IdIndexMapping immutableCopy()

Make an immutable copy of this index mapping.

Returns:

An immutable copy of the index mapping.