def run(self, loss_current_iteration=0, use_pretrained=False):
        """
        Runs the training
        :return:
        :rtype:
        """

        start_iteration = copy.copy(loss_current_iteration)

        DCE = DenseCorrespondenceEvaluation

        self.setup()
        self.save_configs()

        if not use_pretrained:
            # create new network and optimizer
            self._dcn = self.build_network()
            self._optimizer = self._construct_optimizer(self._dcn.parameters())
        else:
            logging.info("using pretrained model")
            if (self._dcn is None):
                raise ValueError("you must set self._dcn if use_pretrained=True")
            if (self._optimizer is None):
                raise ValueError("you must set self._optimizer if use_pretrained=True")

        # make sure network is using cuda and is in train mode
        dcn = self._dcn
        dcn.cuda()
        dcn.train()

        optimizer = self._optimizer
        batch_size = self._data_loader.batch_size

        pixelwise_contrastive_loss = PixelwiseContrastiveLoss(image_shape=dcn.image_shape, config=self._config['loss_function'])
        pixelwise_contrastive_loss.debug = True

        loss = match_loss = non_match_loss = 0

        max_num_iterations = self._config['training']['num_iterations'] + start_iteration
        logging_rate = self._config['training']['logging_rate']
        save_rate = self._config['training']['save_rate']
        compute_test_loss_rate = self._config['training']['compute_test_loss_rate']

        # logging
        self._logging_dict = dict()
        self._logging_dict['train'] = {"iteration": [], "loss": [], "match_loss": [],
                                           "masked_non_match_loss": [], 
                                           "background_non_match_loss": [],
                                           "blind_non_match_loss": [],
                                           "learning_rate": [],
                                           "different_object_non_match_loss": []}

        self._logging_dict['test'] = {"iteration": [], "loss": [], "match_loss": [],
                                           "non_match_loss": []}

        # save network before starting
        if not use_pretrained:
            self.save_network(dcn, optimizer, 0)

        for epoch in range(50):  # loop over the dataset multiple times

            for i, data in enumerate(self._data_loader, 0):
                loss_current_iteration += 1
                start_iter = time.time()

                match_type, \
                img_a, img_b, \
                matches_a, matches_b, \
                masked_non_matches_a, masked_non_matches_b, \
                background_non_matches_a, background_non_matches_b, \
                blind_non_matches_a, blind_non_matches_b, \
                metadata = data

                if (match_type == -1).all():
                    print "\n empty data, continuing \n"
                    continue


                data_type = metadata["type"][0]
                
                img_a = Variable(img_a.cuda(), requires_grad=False)
                img_b = Variable(img_b.cuda(), requires_grad=False)

                matches_a = Variable(matches_a.cuda().squeeze(0), requires_grad=False)
                matches_b = Variable(matches_b.cuda().squeeze(0), requires_grad=False)
                masked_non_matches_a = Variable(masked_non_matches_a.cuda().squeeze(0), requires_grad=False)
                masked_non_matches_b = Variable(masked_non_matches_b.cuda().squeeze(0), requires_grad=False)

                background_non_matches_a = Variable(background_non_matches_a.cuda().squeeze(0), requires_grad=False)
                background_non_matches_b = Variable(background_non_matches_b.cuda().squeeze(0), requires_grad=False)

                blind_non_matches_a = Variable(blind_non_matches_a.cuda().squeeze(0), requires_grad=False)
                blind_non_matches_b = Variable(blind_non_matches_b.cuda().squeeze(0), requires_grad=False)

                optimizer.zero_grad()
                self.adjust_learning_rate(optimizer, loss_current_iteration)

                # run both images through the network
                image_a_pred = dcn.forward(img_a)
                image_a_pred = dcn.process_network_output(image_a_pred, batch_size)

                image_b_pred = dcn.forward(img_b)
                image_b_pred = dcn.process_network_output(image_b_pred, batch_size)

                # get loss
                loss, match_loss, masked_non_match_loss, \
                background_non_match_loss, blind_non_match_loss = loss_composer.get_loss(pixelwise_contrastive_loss, match_type,
                                                                                image_a_pred, image_b_pred,
                                                                                matches_a,     matches_b,
                                                                                masked_non_matches_a, masked_non_matches_b,
                                                                                background_non_matches_a, background_non_matches_b,
                                                                                blind_non_matches_a, blind_non_matches_b)
                

                loss.backward()
                optimizer.step()

                elapsed = time.time() - start_iter

                print "single iteration took %.3f seconds" %(elapsed)


                def update_visdom_plots(loss, match_loss, masked_non_match_loss, background_non_match_loss, blind_non_match_loss):
                    """
                    Updates the visdom plots with current loss function information
                    :return:
                    :rtype:
                    """

                    learning_rate = DenseCorrespondenceTraining.get_learning_rate(optimizer)
                    self._logging_dict['train']['learning_rate'].append(learning_rate)
                    self._visdom_plots['learning_rate'].log(loss_current_iteration, learning_rate)
                    self._tensorboard_logger.log_value("learning rate", learning_rate, loss_current_iteration)


                    # Don't update any plots if the entry corresponding to that term
                    # is a zero loss
                    if not loss_composer.is_zero_loss(match_loss):
                        self._logging_dict['train']['match_loss'].append(match_loss.data[0])
                        self._visdom_plots['train']['match_loss'].log(loss_current_iteration, match_loss.data[0])
                        self._tensorboard_logger.log_value("train match loss", match_loss.data[0], loss_current_iteration)

                    if not loss_composer.is_zero_loss(masked_non_match_loss):
                        self._logging_dict['train']['masked_non_match_loss'].append(masked_non_match_loss.data[0])
                        self._visdom_plots['train']['masked_non_match_loss'].log(loss_current_iteration,
                                                             masked_non_match_loss.data[0])
                        self._tensorboard_logger.log_value("train masked non match loss", masked_non_match_loss.data[0], loss_current_iteration)

                    if not loss_composer.is_zero_loss(background_non_match_loss):
                        self._logging_dict['train']['background_non_match_loss'].append(background_non_match_loss.data[0])
                        self._visdom_plots['train']['background_non_match_loss'].log(loss_current_iteration,
                                                             background_non_match_loss.data[0])
                        self._tensorboard_logger.log_value("train background non match loss", background_non_match_loss.data[0], loss_current_iteration)

                    if not loss_composer.is_zero_loss(blind_non_match_loss):

                        if data_type == SpartanDatasetDataType.SINGLE_OBJECT_WITHIN_SCENE:
                            self._tensorboard_logger.log_value("train blind SINGLE_OBJECT_WITHIN_SCENE", blind_non_match_loss.data[0], loss_current_iteration)

                        if data_type == SpartanDatasetDataType.DIFFERENT_OBJECT:
                            self._tensorboard_logger.log_value("train blind DIFFERENT_OBJECT", blind_non_match_loss.data[0], loss_current_iteration)


                    # loss is never zero
                    if data_type == SpartanDatasetDataType.SINGLE_OBJECT_WITHIN_SCENE:
                        self._tensorboard_logger.log_value("train loss SINGLE_OBJECT_WITHIN_SCENE", loss.data[0], loss_current_iteration)

                    elif data_type == SpartanDatasetDataType.DIFFERENT_OBJECT:
                        self._tensorboard_logger.log_value("train loss DIFFERENT_OBJECT", loss.data[0], loss_current_iteration)

                    elif data_type == SpartanDatasetDataType.SINGLE_OBJECT_ACROSS_SCENE:
                        self._tensorboard_logger.log_value("train loss SINGLE_OBJECT_ACROSS_SCENE", loss.data[0], loss_current_iteration)

                    elif data_type == SpartanDatasetDataType.MULTI_OBJECT:
                        self._tensorboard_logger.log_value("train loss MULTI_OBJECT", loss.data[0], loss_current_iteration)
                    
                    elif data_type == SpartanDatasetDataType.SYNTHETIC_MULTI_OBJECT:
                        self._tensorboard_logger.log_value("train loss SYNTHETIC_MULTI_OBJECT", loss.data[0], loss_current_iteration)
                    else:
                        raise ValueError("unknown data type")


                    if data_type == SpartanDatasetDataType.DIFFERENT_OBJECT:
                        self._tensorboard_logger.log_value("train different object", loss.data[0], loss_current_iteration)

                    # #non_match_type = metadata['non_match_type'][0]
                    # fraction_hard_negatives = pixelwise_contrastive_loss.debug_data['fraction_hard_negatives']

                    # if pixelwise_contrastive_loss.debug:
                    #     if non_match_type == "masked":
                    #         self._visdom_plots['masked_hard_negative_rate'].log(loss_current_iteration, fraction_hard_negatives)
                    #         self._tensorboard_logger.log_value("masked hard negative rate", fraction_hard_negatives, loss_current_iteration)
                    #     elif non_match_type == "non_masked":
                    #         self._visdom_plots['non_masked_hard_negative_rate'].log(loss_current_iteration,
                    #                                                             fraction_hard_negatives)

                    #         self._tensorboard_logger.log_value("non-masked hard negative rate", fraction_hard_negatives,
                    #                                      loss_current_iteration)
                    #     else:
                    #         raise ValueError("uknown non_match_type %s" %(non_match_type))


                # def update_visdom_test_loss_plots(test_loss, test_match_loss, test_non_match_loss):
                #     """
                #     Log data about test loss and update the visdom plots
                #     :return:
                #     :rtype:
                #     """

                #     self._logging_dict['test']['loss'].append(test_loss)
                #     self._logging_dict['test']['match_loss'].append(test_match_loss)
                #     self._logging_dict['test']['non_match_loss'].append(test_non_match_loss)
                #     self._logging_dict['test']['iteration'].append(loss_current_iteration)


                #     self._visdom_plots['test']['loss'].log(loss_current_iteration, test_loss)
                #     self._visdom_plots['test']['match_loss'].log(loss_current_iteration, test_match_loss)
                #     self._visdom_plots['test']['non_match_loss'].log(loss_current_iteration, test_non_match_loss)

                #     self._tensorboard_logger.log_value('test loss', test_loss, loss_current_iteration)
                #     self._tensorboard_logger.log_value('test match loss', test_match_loss, loss_current_iteration)
                #     self._tensorboard_logger.log_value('test non-match loss', test_non_match_loss, loss_current_iteration)



                update_visdom_plots(loss, match_loss, masked_non_match_loss, background_non_match_loss, blind_non_match_loss)

                if loss_current_iteration % save_rate == 0:
                    self.save_network(dcn, optimizer, loss_current_iteration, logging_dict=self._logging_dict)

                if loss_current_iteration % logging_rate == 0:
                    logging.info("Training on iteration %d of %d" %(loss_current_iteration, max_num_iterations))

                    logging.info("single iteration took %.3f seconds" %(elapsed))

                    percent_complete = loss_current_iteration * 100.0/(max_num_iterations - start_iteration)
                    logging.info("Training is %d percent complete\n" %(percent_complete))


                # don't compute the test loss on the first few times through the loop
                if self._config["training"]["compute_test_loss"] and (loss_current_iteration % compute_test_loss_rate == 0) and loss_current_iteration > 5:
                    logging.info("Computing test loss")

                    # delete the loss, match_loss, non_match_loss variables so that
                    # pytorch can use that GPU memory
                    del loss, match_loss, masked_non_match_loss, background_non_match_loss, blind_non_match_loss
                    gc.collect()

                    dcn.eval()
                    test_loss, test_match_loss, test_non_match_loss = DCE.compute_loss_on_dataset(dcn,
                                                                                                  self._data_loader_test, self._config['loss_function'], num_iterations=self._config['training']['test_loss_num_iterations'])

                    update_visdom_test_loss_plots(test_loss, test_match_loss, test_non_match_loss)

                    # delete these variables so we can free GPU memory
                    del test_loss, test_match_loss, test_non_match_loss

                    # make sure to set the network back to train mode
                    dcn.train()

                if loss_current_iteration % self._config['training']['garbage_collect_rate'] == 0:
                    logging.debug("running garbage collection")
                    gc_start = time.time()
                    gc.collect()
                    gc_elapsed = time.time() - gc_start
                    logging.debug("garbage collection took %.2d seconds" %(gc_elapsed))

                if loss_current_iteration > max_num_iterations:
                    logging.info("Finished testing after %d iterations" % (max_num_iterations))
                    self.save_network(dcn, optimizer, loss_current_iteration, logging_dict=self._logging_dict)
                    return
    def run(self, loss_current_iteration=0, use_pretrained=False):
        """
        Runs the training
        :return:
        :rtype:
        """

        start_iteration = copy.copy(loss_current_iteration)

        DCE = DenseCorrespondenceEvaluation

        self.setup()
        self.save_configs()

        if not use_pretrained:
            # create new network and optimizer
            self._dcn = self.build_network()
            self._optimizer = self._construct_optimizer(self._dcn.parameters())
        else:
            logging.info("using pretrained model")
            if (self._dcn is None):
                raise ValueError(
                    "you must set self._dcn if use_pretrained=True")
            if (self._optimizer is None):
                raise ValueError(
                    "you must set self._optimizer if use_pretrained=True")

        # make sure network is using cuda and is in train mode
        dcn = self._dcn
        dcn.cuda()
        dcn.train()

        optimizer = self._optimizer
        batch_size = self._data_loader.batch_size

        pixelwise_contrastive_loss = PixelwiseContrastiveLoss(
            image_shape=dcn.image_shape, config=self._config['loss_function'])
        pixelwise_contrastive_loss.debug = True

        loss = match_loss = non_match_loss = 0

        max_num_iterations = self._config['training'][
            'num_iterations'] + start_iteration
        logging_rate = self._config['training']['logging_rate']
        save_rate = self._config['training']['save_rate']
        compute_test_loss_rate = self._config['training'][
            'compute_test_loss_rate']

        # logging
        self._logging_dict = dict()
        self._logging_dict['train'] = {
            "iteration": [],
            "loss": [],
            "match_loss": [],
            "masked_non_match_loss": [],
            "background_non_match_loss": [],
            "blind_non_match_loss": [],
            "learning_rate": [],
            "different_object_non_match_loss": []
        }

        self._logging_dict['test'] = {
            "iteration": [],
            "loss": [],
            "match_loss": [],
            "non_match_loss": []
        }

        # save network before starting
        if not use_pretrained:
            self.save_network(dcn, optimizer, 0)

        # from training_progress_visualizer import TrainingProgressVisualizer
        # TPV = TrainingProgressVisualizer()

        for epoch in range(50):  # loop over the dataset multiple times

            for i, data in enumerate(self._data_loader, 0):
                loss_current_iteration += 1
                start_iter = time.time()

                match_type, \
                img_a, img_b, \
                matches_a, matches_b, \
                masked_non_matches_a, masked_non_matches_b, \
                background_non_matches_a, background_non_matches_b, \
                blind_non_matches_a, blind_non_matches_b, \
                metadata = data

                if (match_type == -1).all():
                    print("\n empty data, continuing \n")
                    continue

                data_type = metadata["type"][0]

                img_a = Variable(img_a.cuda(), requires_grad=False)
                img_b = Variable(img_b.cuda(), requires_grad=False)

                matches_a = Variable(matches_a.cuda().squeeze(0),
                                     requires_grad=False)
                matches_b = Variable(matches_b.cuda().squeeze(0),
                                     requires_grad=False)
                masked_non_matches_a = Variable(
                    masked_non_matches_a.cuda().squeeze(0),
                    requires_grad=False)
                masked_non_matches_b = Variable(
                    masked_non_matches_b.cuda().squeeze(0),
                    requires_grad=False)

                background_non_matches_a = Variable(
                    background_non_matches_a.cuda().squeeze(0),
                    requires_grad=False)
                background_non_matches_b = Variable(
                    background_non_matches_b.cuda().squeeze(0),
                    requires_grad=False)

                blind_non_matches_a = Variable(
                    blind_non_matches_a.cuda().squeeze(0), requires_grad=False)
                blind_non_matches_b = Variable(
                    blind_non_matches_b.cuda().squeeze(0), requires_grad=False)

                optimizer.zero_grad()
                self.adjust_learning_rate(optimizer, loss_current_iteration)

                # run both images through the network
                image_a_pred = dcn.forward(img_a)
                image_a_pred = dcn.process_network_output(
                    image_a_pred, batch_size)

                image_b_pred = dcn.forward(img_b)
                image_b_pred = dcn.process_network_output(
                    image_b_pred, batch_size)

                # get loss
                loss, match_loss, masked_non_match_loss, \
                background_non_match_loss, blind_non_match_loss = loss_composer.get_loss(pixelwise_contrastive_loss, match_type,
                                                                                image_a_pred, image_b_pred,
                                                                                matches_a,     matches_b,
                                                                                masked_non_matches_a, masked_non_matches_b,
                                                                                background_non_matches_a, background_non_matches_b,
                                                                                blind_non_matches_a, blind_non_matches_b)

                loss.backward()
                optimizer.step()

                #if i % 10 == 0:
                # TPV.update(self._dataset, dcn, loss_current_iteration, now_training_object_id=metadata["object_id"])

                elapsed = time.time() - start_iter

                def update_plots(loss, match_loss, masked_non_match_loss,
                                 background_non_match_loss,
                                 blind_non_match_loss):
                    """
                    Updates the tensorboard plots with current loss function information
                    :return:
                    :rtype:
                    """

                    learning_rate = DenseCorrespondenceTraining.get_learning_rate(
                        optimizer)
                    self._logging_dict['train']['learning_rate'].append(
                        learning_rate)
                    self._tensorboard_logger.log_value("learning rate",
                                                       learning_rate,
                                                       loss_current_iteration)

                    # Don't update any plots if the entry corresponding to that term
                    # is a zero loss
                    if not loss_composer.is_zero_loss(match_loss):
                        self._logging_dict['train']['match_loss'].append(
                            match_loss.item())
                        self._tensorboard_logger.log_value(
                            "train match loss", match_loss.item(),
                            loss_current_iteration)

                    if not loss_composer.is_zero_loss(masked_non_match_loss):
                        self._logging_dict['train'][
                            'masked_non_match_loss'].append(
                                masked_non_match_loss.item())

                        self._tensorboard_logger.log_value(
                            "train masked non match loss",
                            masked_non_match_loss.item(),
                            loss_current_iteration)

                    if not loss_composer.is_zero_loss(
                            background_non_match_loss):
                        self._logging_dict['train'][
                            'background_non_match_loss'].append(
                                background_non_match_loss.item())
                        self._tensorboard_logger.log_value(
                            "train background non match loss",
                            background_non_match_loss.item(),
                            loss_current_iteration)

                    if not loss_composer.is_zero_loss(blind_non_match_loss):

                        if data_type == SpartanDatasetDataType.SINGLE_OBJECT_WITHIN_SCENE:
                            self._tensorboard_logger.log_value(
                                "train blind SINGLE_OBJECT_WITHIN_SCENE",
                                blind_non_match_loss.item(),
                                loss_current_iteration)

                        if data_type == SpartanDatasetDataType.DIFFERENT_OBJECT:
                            self._tensorboard_logger.log_value(
                                "train blind DIFFERENT_OBJECT",
                                blind_non_match_loss.item(),
                                loss_current_iteration)

                    # loss is never zero
                    if data_type == SpartanDatasetDataType.SINGLE_OBJECT_WITHIN_SCENE:
                        self._tensorboard_logger.log_value(
                            "train loss SINGLE_OBJECT_WITHIN_SCENE",
                            loss.item(), loss_current_iteration)

                    elif data_type == SpartanDatasetDataType.DIFFERENT_OBJECT:
                        self._tensorboard_logger.log_value(
                            "train loss DIFFERENT_OBJECT", loss.item(),
                            loss_current_iteration)

                    elif data_type == SpartanDatasetDataType.SINGLE_OBJECT_ACROSS_SCENE:
                        self._tensorboard_logger.log_value(
                            "train loss SINGLE_OBJECT_ACROSS_SCENE",
                            loss.item(), loss_current_iteration)

                    elif data_type == SpartanDatasetDataType.MULTI_OBJECT:
                        self._tensorboard_logger.log_value(
                            "train loss MULTI_OBJECT", loss.item(),
                            loss_current_iteration)

                    elif data_type == SpartanDatasetDataType.SYNTHETIC_MULTI_OBJECT:
                        self._tensorboard_logger.log_value(
                            "train loss SYNTHETIC_MULTI_OBJECT", loss.item(),
                            loss_current_iteration)
                    else:
                        raise ValueError("unknown data type")

                    if data_type == SpartanDatasetDataType.DIFFERENT_OBJECT:
                        self._tensorboard_logger.log_value(
                            "train different object", loss.item(),
                            loss_current_iteration)

                update_plots(loss, match_loss, masked_non_match_loss,
                             background_non_match_loss, blind_non_match_loss)

                if loss_current_iteration % save_rate == 0:
                    self.save_network(dcn,
                                      optimizer,
                                      loss_current_iteration,
                                      logging_dict=self._logging_dict)

                if loss_current_iteration % logging_rate == 0:
                    logging.info("Training on iteration %d of %d" %
                                 (loss_current_iteration, max_num_iterations))

                    logging.info("single iteration took %.3f seconds" %
                                 (elapsed))

                    percent_complete = loss_current_iteration * 100.0 / (
                        max_num_iterations - start_iteration)
                    logging.info("Training is %d percent complete\n" %
                                 (percent_complete))

                # don't compute the test loss on the first few times through the loop
                if self._config["training"]["compute_test_loss"] and (
                        loss_current_iteration % compute_test_loss_rate
                        == 0) and loss_current_iteration > 5:
                    logging.info("Computing test loss")

                    # delete the loss, match_loss, non_match_loss variables so that
                    # pytorch can use that GPU memory
                    del loss, match_loss, masked_non_match_loss, background_non_match_loss, blind_non_match_loss
                    gc.collect()

                    dcn.eval()
                    test_loss, test_match_loss, test_non_match_loss = DCE.compute_loss_on_dataset(
                        dcn,
                        self._data_loader_test,
                        self._config['loss_function'],
                        num_iterations=self._config['training']
                        ['test_loss_num_iterations'])

                    # delete these variables so we can free GPU memory
                    del test_loss, test_match_loss, test_non_match_loss

                    # make sure to set the network back to train mode
                    dcn.train()

                if loss_current_iteration % self._config['training'][
                        'garbage_collect_rate'] == 0:
                    logging.debug("running garbage collection")
                    gc_start = time.time()
                    gc.collect()
                    gc_elapsed = time.time() - gc_start
                    logging.debug("garbage collection took %.2d seconds" %
                                  (gc_elapsed))

                if loss_current_iteration > max_num_iterations:
                    logging.info("Finished testing after %d iterations" %
                                 (max_num_iterations))
                    self.save_network(dcn,
                                      optimizer,
                                      loss_current_iteration,
                                      logging_dict=self._logging_dict)
                    return
Ejemplo n.º 3
0
    def run(self, loss_current_iteration=0, use_pretrained=False):
        """
        Runs the training
        :return:
        :rtype:
        """

        start_iteration = copy.copy(loss_current_iteration)

        DCE = DenseCorrespondenceEvaluation

        self.setup()
        self.save_configs()

        if not use_pretrained:
            # create new network and optimizer
            self._dcn = self.build_network()
            self._optimizer = self._construct_optimizer(self._dcn.parameters())
        else:
            logging.info("using pretrained model")
            if (self._dcn is None):
                raise ValueError("you must set self._dcn if use_pretrained=True")
            if (self._optimizer is None):
                raise ValueError("you must set self._optimizer if use_pretrained=True")

        # make sure network is using cuda and is in train mode
        dcn = self._dcn
        dcn.cuda()
        dcn.train()

        optimizer = self._optimizer
        batch_size = self._data_loader.batch_size

        pixelwise_contrastive_loss = PixelwiseContrastiveLoss(image_shape=dcn.image_shape, config=self._config['loss_function'])
        pixelwise_contrastive_loss.debug = True

        # Repeat M for background and masked
        pixelwise_contrastive_loss._config['M_background'] = pixelwise_contrastive_loss._config['M_descriptor']
        pixelwise_contrastive_loss._config['M_masked'] = pixelwise_contrastive_loss._config['M_descriptor']

        loss = match_loss = non_match_loss = 0

        num_epochs = self._config['training']['num_epochs']
        logging_rate = self._config['training']['logging_rate']
        save_rate = self._config['training']['save_rate']
        compute_test_loss_rate = self._config['training']['compute_test_loss_rate']

        # logging
        self._logging_dict = dict()
        self._logging_dict['train'] = {"iteration": [], "loss": [], "match_loss": [],
                                           "masked_non_match_loss": [], 
                                           "background_non_match_loss": [],
                                           "blind_non_match_loss": [],
                                           "learning_rate": [],
                                           "different_object_non_match_loss": []}

        self._logging_dict['test'] = {"iteration": [], "loss": [], "match_loss": [],
                                           "non_match_loss": []}

        # save network before starting
        if not use_pretrained:
            self.save_network(dcn, optimizer, 0)

        t_start = time.time()
        loss_vec = []
        match_loss_vec = []
        non_match_loss_vec = []
        for epoch in range(num_epochs):  # loop over the dataset multiple times
            for i, data in enumerate(self._data_loader, 0):
                loss_current_iteration += 1
                start_iter = time.time()

                match_type, img_a, img_b, matches_a, matches_b, non_matches_a, non_matches_b = data
                
                img_a = Variable(img_a.cuda(), requires_grad=False)
                img_b = Variable(img_b.cuda(), requires_grad=False)

                # Note: repeat non_matches for both masked and background, and fake blind nonmatches using empty tensor, for compatibility in loss computation
                matches_a = Variable(matches_a.cuda().squeeze(0), requires_grad=False)
                matches_b = Variable(matches_b.cuda().squeeze(0), requires_grad=False)
                non_matches_a = Variable(non_matches_a.cuda().squeeze(0), requires_grad=False)
                non_matches_b = Variable(non_matches_b.cuda().squeeze(0), requires_grad=False)
                blind_non_matches_a = Variable(SpartanDataset.empty_tensor().cuda().squeeze(0), requires_grad=False)
                blind_non_matches_b = Variable(SpartanDataset.empty_tensor().cuda().squeeze(0), requires_grad=False)

                optimizer.zero_grad()
                self.adjust_learning_rate(optimizer, loss_current_iteration)

                # run both images through the network
                image_a_pred = dcn.forward(img_a)
                image_a_pred = dcn.process_network_output(image_a_pred, batch_size)

                image_b_pred = dcn.forward(img_b)
                image_b_pred = dcn.process_network_output(image_b_pred, batch_size)

                # get loss.
                loss, match_loss, non_match_loss, masked_non_match_loss, background_non_match_loss, blind_non_match_loss \
                    = loss_composer.get_loss(pixelwise_contrastive_loss, match_type,
                                            image_a_pred, image_b_pred,
                                            matches_a,     matches_b,
                                            non_matches_a, non_matches_b,
                                            non_matches_a, non_matches_b,
                                            blind_non_matches_a, blind_non_matches_b)
                

                loss.backward()
                optimizer.step()
                elapsed = time.time() - start_iter

                # print "single iteration took %.3f seconds" %(elapsed)

                if loss_current_iteration % save_rate == 0:
                    self.save_network(dcn, optimizer, loss_current_iteration, logging_dict=self._logging_dict)

                sys.stdout.write('Epoch %d/%d, Image %d/%d, total_itr: %d, loss: %.4f, match_loss: %.4f, non_match_loss: %.4f, total_time: %s \r' % \
                    (epoch+1, num_epochs, i+1, len(self._dataset), loss_current_iteration, loss.data[0],  match_loss.data[0], non_match_loss.data[0], str(timedelta(seconds=time.time()-t_start))[:-4])); sys.stdout.flush()

                loss_vec.append(loss.data[0])
                match_loss_vec.append(match_loss.data[0])
                non_match_loss_vec.append(non_match_loss.data[0])

                if self._config["training"]["compute_test_loss"] and (loss_current_iteration % compute_test_loss_rate == 0):
                    print
                    # logging.info("Computing test loss")

                    # delete the loss, match_loss, non_match_loss variables so that
                    # pytorch can use that GPU memory
                    del loss, match_loss, non_match_loss, masked_non_match_loss, background_non_match_loss, blind_non_match_loss
                    gc.collect()

                    print '\tTraining average:loss: %.4f, match_loss: %.4f, non_match_loss: %.4f' % \
                            (np.mean(loss_vec), np.mean(match_loss_vec), np.mean(non_match_loss_vec))
                    loss_vec = []
                    match_loss_vec = []
                    non_match_loss_vec = []
                    
                    dcn.eval()
                    test_loss, test_match_loss, test_non_match_loss = DCE.compute_loss_on_salad_dataset(dcn,
                                                                                                  self._data_loader_test, self._config['loss_function'], num_iterations=self._config['training']['test_loss_num_iterations'])

                    print '\tTesting results: loss: %.4f, match_loss: %.4f, non_match_loss: %.4f' % \
                        (test_loss,  test_match_loss, test_non_match_loss)

                    # delete these variables so we can free GPU memory
                    del test_loss, test_match_loss, test_non_match_loss

                    # make sure to set the network back to train mode
                    dcn.train()

                if loss_current_iteration % self._config['training']['garbage_collect_rate'] == 0:
                    logging.debug("running garbage collection")
                    gc_start = time.time()
                    gc.collect()
                    gc_elapsed = time.time() - gc_start
                    logging.debug("garbage collection took %.2d seconds" %(gc_elapsed))

        logging.info("Finished training.")
        self.save_network(dcn, optimizer, loss_current_iteration, logging_dict=self._logging_dict)
        return