org.grouplens.lenskit.eval.metrics

Class AbstractMetric<X,G,U>

java.lang.Object

org.grouplens.lenskit.eval.metrics.AbstractMetric<X,G,U>

Type Parameters:

X - The context type.

U - The type of per-user results. This is a plain Java class that has fields or methods annotated with ResultColumn containing the per-user output columns.

G - The type of global results. This is a plain Java class that has fields or methods annotated with ResultColumn containing the aggregate output columns.

All Implemented Interfaces:

Closeable, AutoCloseable, Metric<X>

Direct Known Subclasses:

CoveragePredictMetric, EntropyPredictMetric, HLUtilityPredictMetric, IndependentRecallTopNMetric, MAEPredictMetric, MAPTopNMetric, MRRTopNMetric, NDCGPredictMetric, NDCGTopNMetric, OutputPredictMetric, OutputTopNMetric, PrecisionRecallTopNMetric, RMSEPredictMetric, TopNEntropyMetric, TopNLengthMetric, TopNPopularityMetric

public abstract class AbstractMetric<X,G,U>
extends Object
implements Metric<X>

A simple metric base class that tracks the current evaluation.

Since:

0.10

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractMetric(Class<G> aggregate, Class<U> user)

Method Summary

Modifier and Type	Method and Description
void	close() Close the metric.
protected abstract U	doMeasureUser(TestUser user, X context) Measure a user with typed results.
List<String>	getColumnLabels() Get labels for the aggregate columns output by this evaluator.
protected String	getPrefix() A prefix to be applied to column names.
List<Object>	getResults(X context) Get the aggregate results from an accumulator.
protected String	getSuffix() A suffix to be applied to column names.
protected abstract G	getTypedResults(X context) Get the typed results from an accumulator.
List<String>	getUserColumnLabels() Get labels for the per-user columns output by this evaluator.
List<Object>	measureUser(TestUser user, X context) Measure a user in the evaluation.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.grouplens.lenskit.eval.metrics.Metric

createContext

Constructor Detail

AbstractMetric

protected AbstractMetric(Class<G> aggregate,
                         Class<U> user)

Method Detail

getPrefix

protected String getPrefix()

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

Returns:

The prefix to apply to column names.

getSuffix

protected String getSuffix()

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

Returns:

The suffix to apply to column names.

getColumnLabels

public List<String> getColumnLabels()

Description copied from interface: Metric

Get labels for the aggregate columns output by this evaluator.

Specified by:

getColumnLabels in interface Metric<X>

Returns:

The labels for this evaluator's output, used as column headers when outputting the results table.

getUserColumnLabels

public List<String> getUserColumnLabels()

Description copied from interface: Metric

Get labels for the per-user columns output by this evaluator.

Specified by:

getUserColumnLabels in interface Metric<X>

Returns:

The labels for this evaluator's per-user output, used as column headers when outputting the results table.

See Also:

Metric.measureUser(TestUser, Object)

measureUser

@Nonnull
public List<Object> measureUser(TestUser user,
                                         X context)

Description copied from interface: Metric

Measure a user in the evaluation.

Specified by:

measureUser in interface Metric<X>

Parameters:

user - The user to evaluate.

context - The context for the active experimental condition.

Returns:

The table rows resulting from this user's measurement.

doMeasureUser

protected abstract U doMeasureUser(TestUser user,
                                   X context)

Measure a user with typed results.

Parameters:

user - The user to measure.

context - The context.

Returns:

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

getResults

@Nonnull
public List<Object> getResults(X context)

Description copied from interface: Metric

Get the aggregate results from an accumulator.

Specified by:

getResults in interface Metric<X>

Parameters:

context - The context for an experimental condition.

Returns:

The aggregate results from the accumulator.

getTypedResults

protected abstract G getTypedResults(X context)

Get the typed results from an accumulator.

Parameters:

context - The context.

Returns:

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

close

public void close()
           throws IOException

Close the metric. Many metrics do not need to be closed, so this implementation is a no-op.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException - if there is an error closing the metric.