Trivial.cc

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
 
#include <mva/methods/Trivial.h>
 
#include <framework/logging/Logger.h>
 
namespace Belle2 {
  namespace MVA {
 
    void TrivialOptions::load(const boost::property_tree::ptree& pt)
    {
      int version = pt.get<int>("Trivial_version");
      if (version != 1) {
        B2ERROR("Unknown weightfile version " << std::to_string(version));
        throw std::runtime_error("Unknown weightfile version " + std::to_string(version));
      }
      m_output = pt.get<double>("Trivial_output");
 
      auto numberOfOutputs = pt.get<unsigned int>("Trivial_number_of_multiple_outputs", 0u);
      m_multiple_output.resize(numberOfOutputs);
      for (unsigned int i = 0; i < numberOfOutputs; ++i) {
        m_multiple_output[i] = pt.get<double>(std::string("Trivial_multiple_output") + std::to_string(i));
      }
 
      m_passthrough = pt.get<bool>("Trivial_passthrough", false);
    }
 
    void TrivialOptions::save(boost::property_tree::ptree& pt) const
    {
      pt.put("Trivial_version", 1);
      pt.put("Trivial_output", m_output);
      pt.put("Trivial_number_of_multiple_outputs", m_multiple_output.size());
      for (unsigned int i = 0; i < m_multiple_output.size(); ++i) {
        pt.put(std::string("Trivial_multiple_output") + std::to_string(i), m_multiple_output[i]);
      }
      pt.put("Trivial_passthrough", m_passthrough);
    }
 
    po::options_description TrivialOptions::getDescription()
    {
      po::options_description description("Trivial options");
      description.add_options()
      ("output", po::value<double>(&m_output),
       "Outputs this value for all predictions in binary classification (unless passthrough is enabled).");
      description.add_options()
      ("multiple_output", po::value<std::vector<double>>(&m_multiple_output)->multitoken(),
       "Outputs these values for their respective classes in multiclass classification (unless passthrough is enabled).");
      description.add_options()
      ("passthrough", po::value<bool>(&m_passthrough),
       "If enabled, the method returns the value of the input variable. For binary classification this option requires the presence of only one input variable. For multiclass classification we require either one input variable which is returned for all classes, or an input variable per class.");
      return description;
    }
 
    TrivialTeacher::TrivialTeacher(const GeneralOptions& general_options,
                                   const TrivialOptions& specific_options) : Teacher(general_options),
      m_specific_options(specific_options) { }
 
    Weightfile TrivialTeacher::train(Dataset& training_data) const
    {
      Weightfile weightfile;
      weightfile.addOptions(m_general_options);
      weightfile.addOptions(m_specific_options);
      weightfile.addSignalFraction(training_data.getSignalFraction());
      return weightfile;
    }
 
    void TrivialExpert::load(Weightfile& weightfile)
    {
      weightfile.getOptions(m_general_options);
      weightfile.getOptions(m_specific_options);
    }
 
    std::vector<float> TrivialExpert::apply(Dataset& test_data) const
    {
      if (m_specific_options.m_passthrough) {
        if (m_general_options.m_variables.size() != 1) {
          B2ERROR("Trivial method in passthrough mode requires exactly 1 input variables. Found " << m_general_options.m_variables.size());
        }
      }
      std::vector<float> probabilities(test_data.getNumberOfEvents());
      for (unsigned int iEvent = 0; iEvent < test_data.getNumberOfEvents(); ++iEvent) {
        test_data.loadEvent(iEvent);
        if (m_specific_options.m_passthrough) {
          probabilities[iEvent] = test_data.m_input[0];
        } else {
          probabilities[iEvent] = m_specific_options.m_output;
        }
      }
      return probabilities;
    }
 
    std::vector<std::vector<float>> TrivialExpert::applyMulticlass(Dataset& test_data) const
    {
      if ((m_general_options.m_nClasses != m_specific_options.m_multiple_output.size()) and (not m_specific_options.m_passthrough)) {
        B2ERROR("The number of classes declared in the general options do not match the number of outputs declared in the specific options for the Trivial expert");
      }
 
      if (m_specific_options.m_passthrough) {
        if ((m_general_options.m_variables.size() != 1) and (m_general_options.m_variables.size() != m_general_options.m_nClasses)) {
          B2ERROR("Trivial method in passthrough mode requires either exactly one input variable or one per class, matching the number of classes declared in the general options. Found "
                  << m_general_options.m_variables.size());
        }
      }
 
      std::vector<std::vector<float>> probabilities(test_data.getNumberOfEvents(), std::vector<float>(m_general_options.m_nClasses));
      for (unsigned int iEvent = 0; iEvent < test_data.getNumberOfEvents(); ++iEvent) {
        test_data.loadEvent(iEvent);
        for (unsigned int iClass = 0; iClass < m_general_options.m_nClasses; ++iClass) {
          if (m_specific_options.m_passthrough) {
            if (m_general_options.m_variables.size() == 1) {
              probabilities[iEvent][iClass] = test_data.m_input[0];
            } else {
              probabilities[iEvent][iClass] = test_data.m_input[iClass];
            }
          } else {
            probabilities[iEvent][iClass] = m_specific_options.m_multiple_output.at(iClass);
          }
        }
      }
      return probabilities;
    }
  }
}