    // Copyright (C) 2012  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_CROSS_VALIDATE_GRAPh_LABELING_TRAINER_H__
    #define DLIB_CROSS_VALIDATE_GRAPh_LABELING_TRAINER_H__

    #include "../array.h"
    #include "../graph_cuts/min_cut.h"
    #include "svm.h"
    #include "cross_validate_graph_labeling_trainer_abstract.h"

    namespace dlib
    {

    // ----------------------------------------------------------------------------------------

        template <
            typename graph_labeler,
            typename graph_type
            >
        matrix<double,1,2> test_graph_labeling_function (
            const graph_labeler& labeler,
            const dlib::array<graph_type>& samples,
            const std::vector<std::vector<bool> >& labels,
            const std::vector<std::vector<double> >& losses
        )
        {
    #ifdef ENABLE_ASSERTS
            std::string reason_for_failure;
            DLIB_ASSERT(is_graph_labeling_problem(samples, labels, reason_for_failure) ,
                "\t matrix test_graph_labeling_function()"
                << "\n\t invalid inputs were given to this function"
                << "\n\t samples.size(): " << samples.size()
                << "\n\t reason_for_failure: " << reason_for_failure
                );
            DLIB_ASSERT((losses.size() == 0 || sizes_match(labels, losses) == true) &&
                        all_values_are_nonnegative(losses) == true,
                    "\t matrix test_graph_labeling_function()"
                    << "\n\t Invalid inputs were given to this function."
                    << "\n\t labels.size():  " << labels.size()
                    << "\n\t losses.size():  " << losses.size()
                    << "\n\t sizes_match(labels,losses): " << sizes_match(labels,losses)
                    << "\n\t all_values_are_nonnegative(losses): " << all_values_are_nonnegative(losses)
                     );
    #endif

            std::vector<bool> temp;
            double num_pos_correct = 0;
            double num_pos = 0;
            double num_neg_correct = 0;
            double num_neg = 0;

            for (unsigned long i = 0; i < samples.size(); ++i)
            {
                labeler(samples[i], temp);

                for (unsigned long j = 0; j < labels[i].size(); ++j)
                {
                    // What is the loss for this example?  It's just 1 unless we have a
                    // per example loss vector.
                    const double loss = (losses.size() == 0) ? 1.0 : losses[i][j];

                    if (labels[i][j])
                    {
                        num_pos += loss;
                        if (temp[j])
                            num_pos_correct += loss;
                    }
                    else
                    {
                        num_neg += loss;
                        if (!temp[j])
                            num_neg_correct += loss;
                    }
                }
            }

            matrix<double, 1, 2> res;
            if (num_pos != 0)
                res(0) = num_pos_correct/num_pos;
            else
                res(0) = 1;
            if (num_neg != 0)
                res(1) = num_neg_correct/num_neg;
            else
                res(1) = 1;
            return res;
        }

        template <
            typename graph_labeler,
            typename graph_type
            >
        matrix<double,1,2> test_graph_labeling_function (
            const graph_labeler& labeler,
            const dlib::array<graph_type>& samples,
            const std::vector<std::vector<bool> >& labels
        )
        {
            std::vector<std::vector<double> > losses;
            return test_graph_labeling_function(labeler, samples, labels, losses);
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename trainer_type,
            typename graph_type
            >
        matrix<double,1,2> cross_validate_graph_labeling_trainer (
            const trainer_type& trainer,
            const dlib::array<graph_type>& samples,
            const std::vector<std::vector<bool> >& labels,
            const std::vector<std::vector<double> >& losses,
            const long folds
        )
        {
    #ifdef ENABLE_ASSERTS
            std::string reason_for_failure;
            DLIB_ASSERT(is_graph_labeling_problem(samples, labels, reason_for_failure),
                "\t matrix cross_validate_graph_labeling_trainer()"
                << "\n\t invalid inputs were given to this function"
                << "\n\t samples.size(): " << samples.size()
                << "\n\t reason_for_failure: " << reason_for_failure
                );
            DLIB_ASSERT( 1 < folds && folds <= static_cast<long>(samples.size()),
                "\t matrix cross_validate_graph_labeling_trainer()"
                << "\n\t invalid inputs were given to this function"
                << "\n\t folds:  " << folds
                );
            DLIB_ASSERT((losses.size() == 0 || sizes_match(labels, losses) == true) &&
                        all_values_are_nonnegative(losses) == true,
                    "\t matrix cross_validate_graph_labeling_trainer()"
                    << "\n\t Invalid inputs were given to this function."
                    << "\n\t labels.size():  " << labels.size()
                    << "\n\t losses.size():  " << losses.size()
                    << "\n\t sizes_match(labels,losses): " << sizes_match(labels,losses)
                    << "\n\t all_values_are_nonnegative(losses): " << all_values_are_nonnegative(losses)
                     );
    #endif

            typedef std::vector<bool> label_type;

            const long num_in_test  = samples.size()/folds;
            const long num_in_train = samples.size() - num_in_test;

            dlib::array<graph_type> samples_test, samples_train;
            std::vector<label_type> labels_test, labels_train;
            std::vector<std::vector<double> > losses_test, losses_train;

            long next_test_idx = 0;

            std::vector<bool> temp;
            double num_pos_correct = 0;
            double num_pos = 0;
            double num_neg_correct = 0;
            double num_neg = 0;

            graph_type gtemp;

            for (long i = 0; i < folds; ++i)
            {
                samples_test.clear();
                labels_test.clear();
                losses_test.clear();
                samples_train.clear();
                labels_train.clear();
                losses_train.clear();

                // load up the test samples
                for (long cnt = 0; cnt < num_in_test; ++cnt)
                {
                    copy_graph(samples[next_test_idx], gtemp);
                    samples_test.push_back(gtemp);
                    labels_test.push_back(labels[next_test_idx]);
                    if (losses.size() != 0)
                        losses_test.push_back(losses[next_test_idx]);
                    next_test_idx = (next_test_idx + 1)%samples.size();
                }

                // load up the training samples
                long next = next_test_idx;
                for (long cnt = 0; cnt < num_in_train; ++cnt)
                {
                    copy_graph(samples[next], gtemp);
                    samples_train.push_back(gtemp);
                    labels_train.push_back(labels[next]);
                    if (losses.size() != 0)
                        losses_train.push_back(losses[next]);
                    next = (next + 1)%samples.size();
                }

                const typename trainer_type::trained_function_type& labeler = trainer.train(samples_train,labels_train,losses_train);

                // check how good labeler is on the test data
                for (unsigned long i = 0; i < samples_test.size(); ++i)
                {
                    labeler(samples_test[i], temp);
                    for (unsigned long j = 0; j < labels_test[i].size(); ++j)
                    {
                        // What is the loss for this example?  It's just 1 unless we have a
                        // per example loss vector.
                        const double loss = (losses_test.size() == 0) ? 1.0 : losses_test[i][j];

                        if (labels_test[i][j])
                        {
                            num_pos += loss;
                            if (temp[j])
                                num_pos_correct += loss;
                        }
                        else
                        {
                            num_neg += loss;
                            if (!temp[j])
                                num_neg_correct += loss;
                        }
                    }
                }

            } // for (long i = 0; i < folds; ++i)

            matrix<double, 1, 2> res;
            if (num_pos != 0)
                res(0) = num_pos_correct/num_pos;
            else
                res(0) = 1;
            if (num_neg != 0)
                res(1) = num_neg_correct/num_neg;
            else
                res(1) = 1;
            return res;
        }

        template <
            typename trainer_type,
            typename graph_type
            >
        matrix<double,1,2> cross_validate_graph_labeling_trainer (
            const trainer_type& trainer,
            const dlib::array<graph_type>& samples,
            const std::vector<std::vector<bool> >& labels,
            const long folds
        )
        {
            std::vector<std::vector<double> > losses;
            return cross_validate_graph_labeling_trainer(trainer, samples, labels, losses, folds);
        }

    // ----------------------------------------------------------------------------------------

    }

    #endif // DLIB_CROSS_VALIDATE_GRAPh_LABELING_TRAINER_H__