Package opennlp.tools.util.eval

Class FMeasure

  • public final class FMeasure
extends Object
    The FMeasure is an utility class for evaluators which measure 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 Detail

      • FMeasure

        public FMeasure()

    • Method Detail

      • getPrecisionScore

        public double getPrecisionScore()
        Retrieves the arithmetic mean of the precision scores calculated for each evaluated sample.
        Returns:
        the arithmetic mean of all precision scores

      • getRecallScore

        public double getRecallScore()
        Retrieves the arithmetic mean of the recall score calculated for each evaluated sample.
        Returns:
        the arithmetic mean of all recall scores

      • getFMeasure

        public double getFMeasure()
        Retrieves the f-measure score. f-measure = 2 * precision * recall / (precision + recall)
        Returns:
        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 fmeasure metric.
        Parameters:
        measure - the fmeasure

      • toString

        public String toString()
        Creates a human read-able String representation.
        Overrides:
        toString in class Object
        Returns:
        the results

      • 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