org.grouplens.lenskit.eval.metrics.topn

Class TopNLengthMetric

java.lang.Object

org.grouplens.lenskit.eval.metrics.AbstractMetric<MeanAccumulator,TopNLengthMetric.Result,TopNLengthMetric.Result>

org.grouplens.lenskit.eval.metrics.topn.TopNLengthMetric

All Implemented Interfaces:

Closeable, AutoCloseable, Metric<MeanAccumulator>

public class TopNLengthMetric
extends AbstractMetric<MeanAccumulator,TopNLengthMetric.Result,TopNLengthMetric.Result>

Metric that measures how long a TopN list actually is.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	TopNLengthMetric.Builder Build a Top-N length metric to measure Top-N lists.
static class	TopNLengthMetric.Result

Constructor Summary

Constructors

Constructor and Description
TopNLengthMetric(String pre, String sfx, int listSize, ItemSelector candidates, ItemSelector exclude)

Method Summary

Modifier and Type	Method and Description
MeanAccumulator	createContext(Attributed algo, TTDataSet ds, Recommender rec) Create the context for an experimental condition (algorithm/data set pair).
TopNLengthMetric.Result	doMeasureUser(TestUser user, MeanAccumulator context) Measure a user with typed results.
protected String	getPrefix() A prefix to be applied to column names.
protected String	getSuffix() A suffix to be applied to column names.
protected TopNLengthMetric.Result	getTypedResults(MeanAccumulator context) Get the typed results from an accumulator.

Methods inherited from class org.grouplens.lenskit.eval.metrics.AbstractMetric

close, getColumnLabels, getResults, getUserColumnLabels, measureUser

Methods inherited from class java.lang.Object

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

Constructor Detail

TopNLengthMetric

public TopNLengthMetric(String pre,
                        String sfx,
                        int listSize,
                        ItemSelector candidates,
                        ItemSelector exclude)

Method Detail

getPrefix

protected String getPrefix()

Description copied from class: AbstractMetric

A prefix to be applied to column names. If non-null, this prefix will be applied and separated with a period.

Overrides:

getPrefix in class AbstractMetric<MeanAccumulator,TopNLengthMetric.Result,TopNLengthMetric.Result>

Returns:

The prefix to apply to column names.

getSuffix

protected String getSuffix()

Description copied from class: AbstractMetric

A suffix to be applied to column names. If non-null, this suffix will be applied and separated with a period.

Overrides:

getSuffix in class AbstractMetric<MeanAccumulator,TopNLengthMetric.Result,TopNLengthMetric.Result>

Returns:

The suffix to apply to column names.

createContext

public MeanAccumulator createContext(Attributed algo,
                                     TTDataSet ds,
                                     Recommender rec)

Description copied from interface: Metric

Create the context for an experimental condition (algorithm/data set pair).

Parameters:

algo - The algorithm.

ds - The data set.

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

Returns:

The accumulator. This will be passed to Metric.measureUser(TestUser, Object). If the metric does not accumulate any results, this method can return null.

doMeasureUser

public TopNLengthMetric.Result doMeasureUser(TestUser user,
                                             MeanAccumulator context)

Description copied from class: AbstractMetric

Measure a user with typed results.

Specified by:

doMeasureUser in class AbstractMetric<MeanAccumulator,TopNLengthMetric.Result,TopNLengthMetric.Result>

Parameters:

user - The user to measure.

context - The context.

Returns:

The results of measuring the user, or null to emit NAs for the user.

getTypedResults

protected TopNLengthMetric.Result getTypedResults(MeanAccumulator context)

Description copied from class: AbstractMetric

Get the typed results from an accumulator.

Specified by:

getTypedResults in class AbstractMetric<MeanAccumulator,TopNLengthMetric.Result,TopNLengthMetric.Result>

Parameters:

context - The context.

Returns:

The results accumulated for this experiment, or null to emit NAs.