org.grouplens.lenskit.util

Class TopNScoredItemAccumulator

java.lang.Object

org.grouplens.lenskit.util.TopNScoredItemAccumulator

All Implemented Interfaces:

ScoredItemAccumulator

public final class TopNScoredItemAccumulator
extends Object
implements ScoredItemAccumulator

Accumulate the top N scored IDs. IDs are sorted by their associated scores.

Constructor Summary

Constructors

Constructor and Description
TopNScoredItemAccumulator(int n) Create a new accumulator to accumulate the top n IDs.

Method Summary

Modifier and Type	Method and Description
List<ScoredId>	finish() Accumulate the scores into a sorted scored list and reset the accumulator.
LongSet	finishSet() Accumulate the scored items into a set.
MutableSparseVector	finishVector() Accumulate the scores into a mutable sparse vector and reset the accumulator.
boolean	isEmpty() Query whether the accumulator is empty.
void	put(long item, double score) Put a new item in the accumulator.
int	size() Get the number of items in the accumulator.

Methods inherited from class java.lang.Object

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

Constructor Detail

TopNScoredItemAccumulator

public TopNScoredItemAccumulator(int n)

Create a new accumulator to accumulate the top n IDs.

Parameters:

n - The number of IDs to retain.

Method Detail

isEmpty

public boolean isEmpty()

Description copied from interface: ScoredItemAccumulator

Query whether the accumulator is empty.

Specified by:

isEmpty in interface ScoredItemAccumulator

Returns:

true if the accumulator has no items.

size

public int size()

Description copied from interface: ScoredItemAccumulator

Get the number of items in the accumulator.

Specified by:

size in interface ScoredItemAccumulator

Returns:

The number of items accumulated so far, up to the maximum items desired from the accumulator.

put

public void put(long item,
                double score)

Description copied from interface: ScoredItemAccumulator

Put a new item in the accumulator. Putting the same item twice does not replace the previous entry - it adds a new entry with the same ID.

Specified by:

put in interface ScoredItemAccumulator

Parameters:

item - The item to add to the accumulator.

score - The item's score.

finish

public List<ScoredId> finish()

Description copied from interface: ScoredItemAccumulator

Accumulate the scores into a sorted scored list and reset the accumulator. Items are sorted in decreasing order of score.

After this method is called, the accumulator is ready for another accumulation.

Specified by:

finish in interface ScoredItemAccumulator

Returns:

The sorted, scored list of items.

finishVector

public MutableSparseVector finishVector()

Description copied from interface: ScoredItemAccumulator

Accumulate the scores into a mutable sparse vector and reset the accumulator.

After this method is called, the accumulator is ready for another accumulation.

Specified by:

finishVector in interface ScoredItemAccumulator

Returns:

A MutableSparseVector of items.

finishSet

public LongSet finishSet()

Description copied from interface: ScoredItemAccumulator

Accumulate the scored items into a set.

Specified by:

finishSet in interface ScoredItemAccumulator

Returns:

The set of items accumulated.