Example #1
0
  /**
   * Calculates the AUC measurment.
   *
   * @param algorithm The optimisation algorithm with a NNTrainingProblem.
   * @return A Vector with the AUC for each NN output.
   */
  @Override
  public Vector getValue(Algorithm algorithm) {
    Vector solution = (Vector) algorithm.getBestSolution().getPosition();
    NNTrainingProblem problem = (NNTrainingProblem) algorithm.getOptimisationProblem();
    StandardPatternDataTable generalisationSet = problem.getGeneralisationSet();
    NeuralNetwork neuralNetwork = problem.getNeuralNetwork();
    neuralNetwork.setWeights(solution);

    // Arrange outputs and target values into ArrayLists.
    ArrayList<ArrayList<Real>> targets = new ArrayList<ArrayList<Real>>();
    ArrayList<ArrayList<Real>> outputs = new ArrayList<ArrayList<Real>>();
    // case of multiple outputs
    if (generalisationSet.getRow(0).getTarget() instanceof Vector) {
      int size = ((Vector) generalisationSet.getRow(0).getTarget()).size();
      for (int i = 0; i < size; ++i) {
        targets.add(new ArrayList<Real>());
        outputs.add(new ArrayList<Real>());
      }

      for (StandardPattern pattern : generalisationSet) {
        Vector target = (Vector) pattern.getTarget();
        Vector output = neuralNetwork.evaluatePattern(pattern);

        for (int curOutput = 0; curOutput < target.size(); ++curOutput) {
          targets.get(curOutput).add((Real) target.get(curOutput));
          outputs.get(curOutput).add((Real) output.get(curOutput));
        }
      }
    }
    // case of single output
    else {
      targets.add(new ArrayList<Real>());
      outputs.add(new ArrayList<Real>());

      for (StandardPattern pattern : generalisationSet) {
        Real target = (Real) pattern.getTarget();
        Vector output = neuralNetwork.evaluatePattern(pattern);

        targets.get(0).add(target);
        outputs.get(0).add((Real) output.get(0));
      }
    }

    // Calculate the Vector of AUC values
    Vector results = Vector.of();
    for (int curOutput = 0; curOutput < outputs.size(); ++curOutput) {
      results.add(Real.valueOf(areaUnderCurve(targets.get(curOutput), outputs.get(curOutput))));
    }

    return results;
  }