#region License Information
/* HeuristicLab
* Copyright (C) 2002-2015 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
*
* This file is part of HeuristicLab.
*
* HeuristicLab is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* HeuristicLab is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with HeuristicLab. If not, see .
*/
#endregion
using System;
using System.Collections.Generic;
using System.Linq;
namespace HeuristicLab.Problems.DataAnalysis {
public class FOneScoreCalculator {
public static double Calculate(IEnumerable originalValues, IEnumerable estimatedValues, out OnlineCalculatorError errorState) {
if (originalValues.Distinct().Skip(2).Any()) {
// TODO: we could use ClassificationPerformanceMeasuresCalculator instead of the ConfusionMatrixCalculator below to handle multi-class problems
throw new ArgumentException("F1 score can only be calculated for binary classification.");
}
var confusionMatrix = ConfusionMatrixCalculator.Calculate(originalValues, estimatedValues, out errorState);
if (!errorState.Equals(OnlineCalculatorError.None)) {
return double.NaN;
}
//only one class has been present => F1 score cannot be calculated
if (confusionMatrix.GetLength(0) != 2 || confusionMatrix.GetLength(1) != 2) {
return double.NaN;
}
return CalculateFOne(confusionMatrix);
}
private static double CalculateFOne(double[,] confusionMatrix) {
double precision = confusionMatrix[0, 0] / (confusionMatrix[0, 0] + confusionMatrix[0, 1]);
double recall = confusionMatrix[0, 0] / (confusionMatrix[0, 0] + confusionMatrix[1, 0]);
return 2 * ((precision * recall) / (precision + recall));
}
}
}