org.lenskit.eval.traintest.recommend

Class TopNPopularityMetric

java.lang.Object

org.lenskit.eval.traintest.metrics.Metric<X>

org.lenskit.eval.traintest.recommend.TopNMetric<X>

org.lenskit.eval.traintest.recommend.ListOnlyTopNMetric<TopNPopularityMetric.Context>

org.lenskit.eval.traintest.recommend.TopNPopularityMetric

public class TopNPopularityMetric
extends ListOnlyTopNMetric<TopNPopularityMetric.Context>

Metric that measures how popular the items in the TopN list are.

This metric is registered with the type name popularity.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	TopNPopularityMetric.Context
static class	TopNPopularityMetric.PopResult

Constructor Summary

Constructors

Constructor and Description
TopNPopularityMetric()

Method Summary

Modifier and Type	Method and Description
TopNPopularityMetric.Context	createContext(AlgorithmInstance algorithm, DataSet dataSet, RecommenderEngine engine) Create the context for an experimental condition (algorithm/data set pair).
MetricResult	getAggregateMeasurements(TopNPopularityMetric.Context context) Get the aggregate results from an accumulator.
java.util.Set<java.lang.Class<?>>	getRequiredRoots() Get the classes on which this metric depends.
MetricResult	measureUser(Recommender rec, TestUser user, int targetLength, LongList recs, TopNPopularityMetric.Context context) Measurement method that only uses the recommend list.

Methods inherited from class org.lenskit.eval.traintest.recommend.ListOnlyTopNMetric

measureUser

Methods inherited from class org.lenskit.eval.traintest.metrics.Metric

getAggregateColumnLabels, getColumnLabels

Methods inherited from class java.lang.Object

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

Constructor Detail

TopNPopularityMetric

public TopNPopularityMetric()

Method Detail

getRequiredRoots

public java.util.Set<java.lang.Class<?>> getRequiredRoots()

Description copied from class: Metric

Get the classes on which this metric depends. These will be added to the roots of each algorithm configuration.

Overrides:

getRequiredRoots in class Metric<TopNPopularityMetric.Context>

Returns:

The required roots for this metric.

createContext

@Nullable
public TopNPopularityMetric.Context createContext(AlgorithmInstance algorithm,
                                                            DataSet dataSet,
                                                            RecommenderEngine engine)

Description copied from class: Metric

Create the context for an experimental condition (algorithm/data set pair). The default implementation returns null.

Note: Contexts must be thread-safe, in that multiple concurrent calls to the appropriate user-measurement function with the same context must be safe. This can be handled either by the context itself, or by the user-measurement function.

Overrides:

createContext in class Metric<TopNPopularityMetric.Context>

Parameters:

algorithm - The algorithm.

dataSet - The data set.

engine - The LensKit recommender engine, if applicable. This can be null for an external algorithm that does not provide a LensKit recommender.

Returns:

The context. This will be passed to the individual measurement methods. If the metric does need to accumulate any results, this method can return null.

measureUser

@Nonnull
public MetricResult measureUser(Recommender rec,
                                         TestUser user,
                                         int targetLength,
                                         LongList recs,
                                         TopNPopularityMetric.Context context)

Description copied from class: ListOnlyTopNMetric

Measurement method that only uses the recommend list.

Thread Safety: This method may be called concurrently by multiple threads with the same recommender and context.

Specified by:

measureUser in class ListOnlyTopNMetric<TopNPopularityMetric.Context>

Parameters:

rec - The recommender used to recommend for this user.

user - The user.

targetLength - The target list length.

recs - The list of recommendations.

context - The context.

Returns:

The results of measuring this user.

getAggregateMeasurements

@Nonnull
public MetricResult getAggregateMeasurements(TopNPopularityMetric.Context context)

Description copied from class: Metric

Get the aggregate results from an accumulator. The default implementation returns MetricResult.empty().

Overrides:

getAggregateMeasurements in class Metric<TopNPopularityMetric.Context>

Parameters:

context - The context for an experimental condition.

Returns:

The aggregate results from the accumulator.