lossmin/minimizers/gradient-evaluator.cc

// Copyright 2014 Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Author: nevena@google.com (Nevena Lazic)

#include "lossmin/minimizers/gradient-evaluator.h"

#include <functional>

namespace lossmin {

double GradientEvaluator::Loss(const Weights &weights) const {
  // TODO(azani): Implement multi-threaded version.
  return loss_function_->BatchLoss(weights, instances_, labels_) /
         NumExamples();
}

double GradientEvaluator::Loss(const Weights &weights,
                               const InstanceSet &validation_instances,
                               const LabelSet &validation_labels) const {
  return loss_function_->BatchLoss(weights, validation_instances,
                                   validation_labels) /
         validation_labels.rows();
}

double GradientEvaluator::Loss(const Weights &weights,
                               const std::vector<int> &example_indices) const {
  double loss = 0.0;
  for (int example : example_indices) {
    loss += loss_function_->ExampleLoss(weights, instances_, labels_, example);
  }
  return loss / example_indices.size();
}

void GradientEvaluator::Gradient(const Weights &weights,
                                 Weights *gradient) const {
  // DCHECK(gradient != nullptr);
  // TODO(azani): Implement multi-threaded version.
  loss_function_->BatchGradient(weights, instances_, labels_, gradient);
  *gradient /= NumExamples();
}

}  // namespace lossmin