org.grouplens.lenskit.util

Interface Index

All Superinterfaces:

Serializable

All Known Implementing Classes:

Indexer

public interface Index
extends Serializable

An index mapping long IDs to consecuitive 0-based integers. The indexes fall in the range [0,getObjectCount()). Indexes must be serializable.

Author:

GroupLens Research

Method Summary

Methods

Modifier and Type	Method and Description
MutableSparseVector	convertArrayToVector(double[] values) This method is used to convert arrays to sparse arrays.
long	getId(int idx) Get the key for an index.
LongList	getIds() Get the list of IDs.
int	getIndex(long id) Get the index of an id.
int	getObjectCount() Get the number of ID in the index.

Method Detail

getIndex

int getIndex(long id)

Get the index of an id. If the object has not been interned, returns a negative number.

Parameters:

id - The id to query.

Returns:

The id's index or a negative value if the id does not exist.

getId

long getId(int idx)

Get the key for an index.

Parameters:

idx - The index of the ID to retrieve.

Returns:

The ID for the given idx

getObjectCount

int getObjectCount()

Get the number of ID in the index.

Returns:

The number of indexed keys.

getIds

LongList getIds()

Get the list of IDs.

Returns:

The list of (unique) IDs in the index.

convertArrayToVector

MutableSparseVector convertArrayToVector(double[] values)

This method is used to convert arrays to sparse arrays. It takes an array of `double` values corresponding to the ids interned in the index and converts it to a sparse vector whose keys are the IDs.

Parameters:

values - A array of double value.

Returns:

A new sparse vector that is converted from the Array.