Package opennlp.tools.util.eval

Class FMeasure

java.lang.Object

opennlp.tools.util.eval.FMeasure

public final class FMeasure
extends Object

The FMeasure is a utility class for evaluators which measures precision, recall and the resulting f-measure.

Evaluation results are the arithmetic mean of the precision scores calculated for each reference sample and the arithmetic mean of the recall scores calculated for each reference sample.

Constructor Summary

Constructors

Constructor	Description
FMeasure()

Method Summary

Modifier and Type	Method	Description
double	getFMeasure()	f-measure = 2 * precision * recall / (precision + recall).
double	getPrecisionScore()
double	getRecallScore()
void	mergeInto(FMeasure measure)	Merge results into metric.
static double	precision(Object[] references, Object[] predictions)	Calculates the precision score for the given reference and predicted spans.
static double	recall(Object[] references, Object[] predictions)	Calculates the recall score for the given reference and predicted spans.
String	toString()
void	updateScores(Object[] references, Object[] predictions)	Updates the score based on the number of true positives and the number of predictions and references.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

FMeasure

public FMeasure()

Method Detail

getPrecisionScore

public double getPrecisionScore()

Returns:

Retrieves the arithmetic mean of the precision scores calculated for each evaluated sample.

getRecallScore

public double getRecallScore()

Returns:

Retrieves the arithmetic mean of the recall score calculated for each evaluated sample.

getFMeasure

public double getFMeasure()

f-measure = 2 * precision * recall / (precision + recall).

Returns:

Retrieves the f-measure or -1 if precision + recall <= 0

updateScores

public void updateScores(Object[] references,
                         Object[] predictions)

Updates the score based on the number of true positives and the number of predictions and references.

Parameters:

references - the provided references

predictions - the predicted spans

mergeInto

public void mergeInto(FMeasure measure)

Merge results into metric.

Parameters:

measure - The FMeasure to merge.

toString

public String toString()

Overrides:

toString in class Object

Returns:

A human-readable String representation.

precision

public static double precision(Object[] references,
                               Object[] predictions)

Calculates the precision score for the given reference and predicted spans.

Parameters:

references - The gold standard spans.

predictions - The predicted spans.

Returns:

The precision score or NaN if there are no predicted spans.

recall

public static double recall(Object[] references,
                            Object[] predictions)

Calculates the recall score for the given reference and predicted spans.

Parameters:

references - The gold standard spans

predictions - The predicted spans

Returns:

The recall score or NaN if there are no reference spans.