Ejemplo n.º 1
0
def main(argv):
    del argv  # unused arg
    tf.io.gfile.makedirs(FLAGS.output_dir)
    logging.info('Saving checkpoints at %s', FLAGS.output_dir)
    tf.random.set_seed(FLAGS.seed)

    train_batch_size = (FLAGS.per_core_batch_size * FLAGS.num_cores //
                        FLAGS.batch_repetitions)
    test_batch_size = FLAGS.per_core_batch_size * FLAGS.num_cores
    steps_per_epoch = APPROX_IMAGENET_TRAIN_IMAGES // train_batch_size
    steps_per_eval = IMAGENET_VALIDATION_IMAGES // test_batch_size

    if FLAGS.use_gpu:
        logging.info('Use GPU')
        strategy = tf.distribute.MirroredStrategy()
    else:
        logging.info('Use TPU at %s',
                     FLAGS.tpu if FLAGS.tpu is not None else 'local')
        resolver = tf.distribute.cluster_resolver.TPUClusterResolver(
            tpu=FLAGS.tpu)
        tf.config.experimental_connect_to_cluster(resolver)
        tf.tpu.experimental.initialize_tpu_system(resolver)
        strategy = tf.distribute.TPUStrategy(resolver)

    builder = utils.ImageNetInput(data_dir=FLAGS.data_dir,
                                  use_bfloat16=FLAGS.use_bfloat16)
    train_dataset = builder.as_dataset(split=tfds.Split.TRAIN,
                                       batch_size=train_batch_size)
    test_dataset = builder.as_dataset(split=tfds.Split.TEST,
                                      batch_size=test_batch_size)
    train_dataset = strategy.experimental_distribute_dataset(train_dataset)
    test_dataset = strategy.experimental_distribute_dataset(test_dataset)

    if FLAGS.use_bfloat16:
        policy = tf.keras.mixed_precision.experimental.Policy('mixed_bfloat16')
        tf.keras.mixed_precision.experimental.set_policy(policy)

    with strategy.scope():
        logging.info('Building Keras ResNet-50 model')
        model = imagenet_model.resnet50(
            input_shape=(FLAGS.ensemble_size, 224, 224, 3),
            num_classes=NUM_CLASSES,
            ensemble_size=FLAGS.ensemble_size,
            width_multiplier=FLAGS.width_multiplier)
        logging.info('Model input shape: %s', model.input_shape)
        logging.info('Model output shape: %s', model.output_shape)
        logging.info('Model number of weights: %s', model.count_params())
        # Scale learning rate and decay epochs by vanilla settings.
        base_lr = FLAGS.base_learning_rate * train_batch_size / 256
        lr_schedule = [  # (multiplier, epoch to start) tuples
            (1.0, FLAGS.lr_warmup_epochs),
            (0.1, int(FLAGS.lr_decay_epochs[0])),
            (0.01, int(FLAGS.lr_decay_epochs[1])),
            (0.001, int(FLAGS.lr_decay_epochs[2]))
        ]
        learning_rate = utils.LearningRateSchedule(steps_per_epoch, base_lr,
                                                   FLAGS.train_epochs,
                                                   lr_schedule)
        optimizer = tf.keras.optimizers.SGD(learning_rate=learning_rate,
                                            momentum=0.9,
                                            nesterov=True)
        metrics = {
            'train/negative_log_likelihood': tf.keras.metrics.Mean(),
            'train/accuracy': tf.keras.metrics.SparseCategoricalAccuracy(),
            'train/loss': tf.keras.metrics.Mean(),
            'train/ece': um.ExpectedCalibrationError(num_bins=FLAGS.num_bins),
            'test/negative_log_likelihood': tf.keras.metrics.Mean(),
            'test/accuracy': tf.keras.metrics.SparseCategoricalAccuracy(),
            'test/ece': um.ExpectedCalibrationError(num_bins=FLAGS.num_bins),
        }

        for i in range(FLAGS.ensemble_size):
            metrics['test/nll_member_{}'.format(i)] = tf.keras.metrics.Mean()
            metrics['test/accuracy_member_{}'.format(i)] = (
                tf.keras.metrics.SparseCategoricalAccuracy())
        test_diversity = {
            'test/disagreement': tf.keras.metrics.Mean(),
            'test/average_kl': tf.keras.metrics.Mean(),
            'test/cosine_similarity': tf.keras.metrics.Mean(),
        }
        logging.info('Finished building Keras ResNet-50 model')

        checkpoint = tf.train.Checkpoint(model=model, optimizer=optimizer)
        latest_checkpoint = tf.train.latest_checkpoint(FLAGS.output_dir)
        initial_epoch = 0
        if latest_checkpoint:
            # checkpoint.restore must be within a strategy.scope() so that optimizer
            # slot variables are mirrored.
            checkpoint.restore(latest_checkpoint)
            logging.info('Loaded checkpoint %s', latest_checkpoint)
            initial_epoch = optimizer.iterations.numpy() // steps_per_epoch

    summary_writer = tf.summary.create_file_writer(
        os.path.join(FLAGS.output_dir, 'summaries'))

    @tf.function
    def train_step(iterator):
        """Training StepFn."""
        def step_fn(inputs):
            """Per-Replica StepFn."""
            images, labels = inputs
            batch_size = tf.shape(images)[0]
            main_shuffle = tf.random.shuffle(
                tf.tile(tf.range(batch_size), [FLAGS.batch_repetitions]))
            to_shuffle = tf.cast(
                tf.cast(tf.shape(main_shuffle)[0], tf.float32) *
                (1. - FLAGS.input_repetition_probability), tf.int32)
            shuffle_indices = [
                tf.concat([
                    tf.random.shuffle(main_shuffle[:to_shuffle]),
                    main_shuffle[to_shuffle:]
                ],
                          axis=0) for _ in range(FLAGS.ensemble_size)
            ]
            images = tf.stack([
                tf.gather(images, indices, axis=0)
                for indices in shuffle_indices
            ],
                              axis=1)
            labels = tf.stack([
                tf.gather(labels, indices, axis=0)
                for indices in shuffle_indices
            ],
                              axis=1)

            with tf.GradientTape() as tape:
                logits = model(images, training=True)
                if FLAGS.use_bfloat16:
                    logits = tf.cast(logits, tf.float32)

                negative_log_likelihood = tf.reduce_mean(
                    tf.reduce_sum(
                        tf.keras.losses.sparse_categorical_crossentropy(
                            labels, logits, from_logits=True),
                        axis=1))
                filtered_variables = []
                for var in model.trainable_variables:
                    # Apply l2 on the weights. This excludes BN parameters and biases, but
                    # pay caution to their naming scheme.
                    if 'kernel' in var.name or 'bias' in var.name:
                        filtered_variables.append(tf.reshape(var, (-1, )))

                l2_loss = FLAGS.l2 * 2 * tf.nn.l2_loss(
                    tf.concat(filtered_variables, axis=0))
                # Scale the loss given the TPUStrategy will reduce sum all gradients.
                loss = negative_log_likelihood + l2_loss
                scaled_loss = loss / strategy.num_replicas_in_sync

            grads = tape.gradient(scaled_loss, model.trainable_variables)
            optimizer.apply_gradients(zip(grads, model.trainable_variables))

            probs = tf.nn.softmax(tf.reshape(logits, [-1, NUM_CLASSES]))
            flat_labels = tf.reshape(labels, [-1])
            metrics['train/ece'].update_state(flat_labels, probs)
            metrics['train/loss'].update_state(loss)
            metrics['train/negative_log_likelihood'].update_state(
                negative_log_likelihood)
            metrics['train/accuracy'].update_state(flat_labels, probs)

        strategy.run(step_fn, args=(next(iterator), ))

    @tf.function
    def test_step(iterator):
        """Evaluation StepFn."""
        def step_fn(inputs):
            """Per-Replica StepFn."""
            images, labels = inputs
            images = tf.tile(tf.expand_dims(images, 1),
                             [1, FLAGS.ensemble_size, 1, 1, 1])
            logits = model(images, training=False)
            if FLAGS.use_bfloat16:
                logits = tf.cast(logits, tf.float32)
            probs = tf.nn.softmax(logits)

            per_probs = tf.transpose(probs, perm=[1, 0, 2])
            diversity_results = um.average_pairwise_diversity(
                per_probs, FLAGS.ensemble_size)
            for k, v in diversity_results.items():
                test_diversity['test/' + k].update_state(v)

            for i in range(FLAGS.ensemble_size):
                member_probs = probs[:, i]
                member_loss = tf.keras.losses.sparse_categorical_crossentropy(
                    labels, member_probs)
                metrics['test/nll_member_{}'.format(i)].update_state(
                    member_loss)
                metrics['test/accuracy_member_{}'.format(i)].update_state(
                    labels, member_probs)

            # Negative log marginal likelihood computed in a numerically-stable way.
            labels_tiled = tf.tile(tf.expand_dims(labels, 1),
                                   [1, FLAGS.ensemble_size])
            log_likelihoods = -tf.keras.losses.sparse_categorical_crossentropy(
                labels_tiled, logits, from_logits=True)
            negative_log_likelihood = tf.reduce_mean(
                -tf.reduce_logsumexp(log_likelihoods, axis=[1]) +
                tf.math.log(float(FLAGS.ensemble_size)))
            probs = tf.math.reduce_mean(probs, axis=1)  # marginalize

            metrics['test/negative_log_likelihood'].update_state(
                negative_log_likelihood)
            metrics['test/accuracy'].update_state(labels, probs)
            metrics['test/ece'].update_state(labels, probs)

        strategy.run(step_fn, args=(next(iterator), ))

    metrics.update({'test/ms_per_example': tf.keras.metrics.Mean()})

    train_iterator = iter(train_dataset)
    start_time = time.time()
    for epoch in range(initial_epoch, FLAGS.train_epochs):
        logging.info('Starting to run epoch: %s', epoch)
        for step in range(steps_per_epoch):
            train_step(train_iterator)

            current_step = epoch * steps_per_epoch + (step + 1)
            max_steps = steps_per_epoch * FLAGS.train_epochs
            time_elapsed = time.time() - start_time
            steps_per_sec = float(current_step) / time_elapsed
            eta_seconds = (max_steps - current_step) / steps_per_sec
            message = ('{:.1%} completion: epoch {:d}/{:d}. {:.1f} steps/s. '
                       'ETA: {:.0f} min. Time elapsed: {:.0f} min'.format(
                           current_step / max_steps, epoch + 1,
                           FLAGS.train_epochs, steps_per_sec, eta_seconds / 60,
                           time_elapsed / 60))
            if step % 20 == 0:
                logging.info(message)

        test_iterator = iter(test_dataset)
        for step in range(steps_per_eval):
            if step % 20 == 0:
                logging.info('Starting to run eval step %s of epoch: %s', step,
                             epoch)
            test_start_time = time.time()
            test_step(test_iterator)
            ms_per_example = (time.time() -
                              test_start_time) * 1e6 / test_batch_size
            metrics['test/ms_per_example'].update_state(ms_per_example)

        logging.info('Train Loss: %.4f, Accuracy: %.2f%%',
                     metrics['train/loss'].result(),
                     metrics['train/accuracy'].result() * 100)
        logging.info('Test NLL: %.4f, Accuracy: %.2f%%',
                     metrics['test/negative_log_likelihood'].result(),
                     metrics['test/accuracy'].result() * 100)
        for i in range(FLAGS.ensemble_size):
            logging.info(
                'Member %d Test Loss: %.4f, Accuracy: %.2f%%', i,
                metrics['test/nll_member_{}'.format(i)].result(),
                metrics['test/accuracy_member_{}'.format(i)].result() * 100)

        total_metrics = metrics.copy()
        total_metrics.update(test_diversity)
        total_results = {
            name: metric.result()
            for name, metric in total_metrics.items()
        }
        with summary_writer.as_default():
            for name, result in total_results.items():
                tf.summary.scalar(name, result, step=epoch + 1)

        for _, metric in total_metrics.items():
            metric.reset_states()

        if (FLAGS.checkpoint_interval > 0
                and (epoch + 1) % FLAGS.checkpoint_interval == 0):
            checkpoint_name = checkpoint.save(
                os.path.join(FLAGS.output_dir, 'checkpoint'))
            logging.info('Saved checkpoint to %s', checkpoint_name)

    final_save_name = os.path.join(FLAGS.output_dir, 'model')
    model.save(final_save_name)
    logging.info('Saved model to %s', final_save_name)
Ejemplo n.º 2
0
def main(argv):
    del argv  # unused arg
    tf.random.set_seed(FLAGS.seed)

    per_core_batch_size = FLAGS.per_core_batch_size // FLAGS.ensemble_size
    batch_size = per_core_batch_size * FLAGS.num_cores
    steps_per_epoch = APPROX_IMAGENET_TRAIN_IMAGES // batch_size
    steps_per_eval = IMAGENET_VALIDATION_IMAGES // batch_size

    logging.info('Saving checkpoints at %s', FLAGS.output_dir)

    if FLAGS.use_gpu:
        logging.info('Use GPU')
        strategy = tf.distribute.MirroredStrategy()
    else:
        logging.info('Use TPU at %s',
                     FLAGS.tpu if FLAGS.tpu is not None else 'local')
        resolver = tf.distribute.cluster_resolver.TPUClusterResolver(
            tpu=FLAGS.tpu)
        tf.config.experimental_connect_to_cluster(resolver)
        tf.tpu.experimental.initialize_tpu_system(resolver)
        strategy = tf.distribute.TPUStrategy(resolver)

    builder = utils.ImageNetInput(data_dir=FLAGS.data_dir,
                                  use_bfloat16=FLAGS.use_bfloat16)
    train_dataset = builder.as_dataset(split=tfds.Split.TRAIN,
                                       batch_size=batch_size)
    clean_test_dataset = builder.as_dataset(split=tfds.Split.TEST,
                                            batch_size=batch_size)
    train_dataset = strategy.experimental_distribute_dataset(train_dataset)
    test_datasets = {
        'clean': strategy.experimental_distribute_dataset(clean_test_dataset)
    }
    if FLAGS.corruptions_interval > 0:
        corruption_types, max_intensity = utils.load_corrupted_test_info()
        for name in corruption_types:
            for intensity in range(1, max_intensity + 1):
                dataset_name = '{0}_{1}'.format(name, intensity)
                dataset = utils.load_corrupted_test_dataset(
                    batch_size=batch_size,
                    corruption_name=name,
                    corruption_intensity=intensity,
                    use_bfloat16=FLAGS.use_bfloat16)
                test_datasets[dataset_name] = (
                    strategy.experimental_distribute_dataset(dataset))

    if FLAGS.use_bfloat16:
        policy = tf.keras.mixed_precision.experimental.Policy('mixed_bfloat16')
        tf.keras.mixed_precision.experimental.set_policy(policy)

    summary_writer = tf.summary.create_file_writer(
        os.path.join(FLAGS.output_dir, 'summaries'))

    with strategy.scope():
        logging.info('Building Keras ResNet-50 model')
        model = imagenet_model.rank1_resnet50(
            input_shape=(224, 224, 3),
            num_classes=NUM_CLASSES,
            alpha_initializer=FLAGS.alpha_initializer,
            gamma_initializer=FLAGS.gamma_initializer,
            alpha_regularizer=FLAGS.alpha_regularizer,
            gamma_regularizer=FLAGS.gamma_regularizer,
            use_additive_perturbation=FLAGS.use_additive_perturbation,
            ensemble_size=FLAGS.ensemble_size,
            random_sign_init=FLAGS.random_sign_init,
            dropout_rate=FLAGS.dropout_rate,
            prior_stddev=FLAGS.prior_stddev,
            use_tpu=not FLAGS.use_gpu)
        logging.info('Model input shape: %s', model.input_shape)
        logging.info('Model output shape: %s', model.output_shape)
        logging.info('Model number of weights: %s', model.count_params())
        # Scale learning rate and decay epochs by vanilla settings.
        base_lr = FLAGS.base_learning_rate * batch_size / 256
        learning_rate = utils.LearningRateSchedule(steps_per_epoch, base_lr,
                                                   FLAGS.train_epochs,
                                                   _LR_SCHEDULE)
        optimizer = tf.keras.optimizers.SGD(learning_rate=learning_rate,
                                            momentum=0.9,
                                            nesterov=True)
        metrics = {
            'train/negative_log_likelihood': tf.keras.metrics.Mean(),
            'train/kl': tf.keras.metrics.Mean(),
            'train/kl_scale': tf.keras.metrics.Mean(),
            'train/elbo': tf.keras.metrics.Mean(),
            'train/loss': tf.keras.metrics.Mean(),
            'train/accuracy': tf.keras.metrics.SparseCategoricalAccuracy(),
            'train/ece': um.ExpectedCalibrationError(num_bins=FLAGS.num_bins),
            'test/negative_log_likelihood': tf.keras.metrics.Mean(),
            'test/kl': tf.keras.metrics.Mean(),
            'test/elbo': tf.keras.metrics.Mean(),
            'test/accuracy': tf.keras.metrics.SparseCategoricalAccuracy(),
            'test/ece': um.ExpectedCalibrationError(num_bins=FLAGS.num_bins),
        }
        if FLAGS.corruptions_interval > 0:
            corrupt_metrics = {}
            for intensity in range(1, max_intensity + 1):
                for corruption in corruption_types:
                    dataset_name = '{0}_{1}'.format(corruption, intensity)
                    corrupt_metrics['test/nll_{}'.format(dataset_name)] = (
                        tf.keras.metrics.Mean())
                    corrupt_metrics['test/kl_{}'.format(dataset_name)] = (
                        tf.keras.metrics.Mean())
                    corrupt_metrics['test/elbo_{}'.format(dataset_name)] = (
                        tf.keras.metrics.Mean())
                    corrupt_metrics['test/accuracy_{}'.format(
                        dataset_name)] = (
                            tf.keras.metrics.SparseCategoricalAccuracy())
                    corrupt_metrics['test/ece_{}'.format(dataset_name)] = (
                        um.ExpectedCalibrationError(num_bins=FLAGS.num_bins))

        test_diversity = {}
        training_diversity = {}
        if FLAGS.ensemble_size > 1:
            for i in range(FLAGS.ensemble_size):
                metrics['test/nll_member_{}'.format(
                    i)] = tf.keras.metrics.Mean()
                metrics['test/accuracy_member_{}'.format(i)] = (
                    tf.keras.metrics.SparseCategoricalAccuracy())
            test_diversity = {
                'test/disagreement': tf.keras.metrics.Mean(),
                'test/average_kl': tf.keras.metrics.Mean(),
                'test/cosine_similarity': tf.keras.metrics.Mean(),
            }
            training_diversity = {
                'train/disagreement': tf.keras.metrics.Mean(),
                'train/average_kl': tf.keras.metrics.Mean(),
                'train/cosine_similarity': tf.keras.metrics.Mean(),
            }

        logging.info('Finished building Keras ResNet-50 model')

        checkpoint = tf.train.Checkpoint(model=model, optimizer=optimizer)
        latest_checkpoint = tf.train.latest_checkpoint(FLAGS.output_dir)
        initial_epoch = 0
        if latest_checkpoint:
            # checkpoint.restore must be within a strategy.scope() so that optimizer
            # slot variables are mirrored.
            checkpoint.restore(latest_checkpoint)
            logging.info('Loaded checkpoint %s', latest_checkpoint)
            initial_epoch = optimizer.iterations.numpy() // steps_per_epoch

    def compute_l2_loss(model):
        filtered_variables = []
        for var in model.trainable_variables:
            # Apply l2 on the BN parameters and bias terms. This
            # excludes only fast weight approximate posterior/prior parameters,
            # but pay caution to their naming scheme.
            if ('kernel' in var.name or 'batch_norm' in var.name
                    or 'bias' in var.name):
                filtered_variables.append(tf.reshape(var, (-1, )))
        l2_loss = FLAGS.l2 * 2 * tf.nn.l2_loss(
            tf.concat(filtered_variables, axis=0))
        return l2_loss

    @tf.function
    def train_step(iterator):
        """Training StepFn."""
        def step_fn(inputs):
            """Per-Replica StepFn."""
            images, labels = inputs
            if FLAGS.ensemble_size > 1:
                images = tf.tile(images, [FLAGS.ensemble_size, 1, 1, 1])
                labels = tf.tile(labels, [FLAGS.ensemble_size])

            with tf.GradientTape() as tape:
                logits = model(images, training=True)
                if FLAGS.use_bfloat16:
                    logits = tf.cast(logits, tf.float32)

                probs = tf.nn.softmax(logits)
                if FLAGS.ensemble_size > 1:
                    per_probs = tf.reshape(
                        probs,
                        tf.concat([[FLAGS.ensemble_size, -1], probs.shape[1:]],
                                  0))
                    diversity_results = um.average_pairwise_diversity(
                        per_probs, FLAGS.ensemble_size)

                negative_log_likelihood = tf.reduce_mean(
                    tf.keras.losses.sparse_categorical_crossentropy(
                        labels, logits, from_logits=True))
                l2_loss = compute_l2_loss(model)
                kl = sum(model.losses) / APPROX_IMAGENET_TRAIN_IMAGES
                kl_scale = tf.cast(optimizer.iterations + 1, kl.dtype)
                kl_scale /= steps_per_epoch * FLAGS.kl_annealing_epochs
                kl_scale = tf.minimum(1., kl_scale)
                kl_loss = kl_scale * kl

                # Scale the loss given the TPUStrategy will reduce sum all gradients.
                loss = negative_log_likelihood + l2_loss + kl_loss
                scaled_loss = loss / strategy.num_replicas_in_sync
                elbo = -(negative_log_likelihood + l2_loss + kl)

            grads = tape.gradient(scaled_loss, model.trainable_variables)

            # Separate learning rate implementation.
            if FLAGS.fast_weight_lr_multiplier != 1.0:
                grads_and_vars = []
                for grad, var in zip(grads, model.trainable_variables):
                    # Apply different learning rate on the fast weights. This excludes BN
                    # and slow weights, but pay caution to the naming scheme.
                    if ('batch_norm' not in var.name
                            and 'kernel' not in var.name):
                        grads_and_vars.append(
                            (grad * FLAGS.fast_weight_lr_multiplier, var))
                    else:
                        grads_and_vars.append((grad, var))
                optimizer.apply_gradients(grads_and_vars)
            else:
                optimizer.apply_gradients(zip(grads,
                                              model.trainable_variables))

            metrics['train/negative_log_likelihood'].update_state(
                negative_log_likelihood)
            metrics['train/kl'].update_state(kl)
            metrics['train/kl_scale'].update_state(kl_scale)
            metrics['train/elbo'].update_state(elbo)
            metrics['train/loss'].update_state(loss)
            metrics['train/accuracy'].update_state(labels, logits)
            metrics['train/ece'].update_state(labels, probs)
            if FLAGS.ensemble_size > 1:
                for k, v in diversity_results.items():
                    training_diversity['train/' + k].update_state(v)

        strategy.run(step_fn, args=(next(iterator), ))

    @tf.function
    def test_step(iterator, dataset_name):
        """Evaluation StepFn."""
        def step_fn(inputs):
            """Per-Replica StepFn."""
            images, labels = inputs
            if FLAGS.ensemble_size > 1:
                images = tf.tile(images, [FLAGS.ensemble_size, 1, 1, 1])
            logits = tf.reshape([
                model(images, training=False)
                for _ in range(FLAGS.num_eval_samples)
            ], [FLAGS.num_eval_samples, FLAGS.ensemble_size, -1, NUM_CLASSES])
            if FLAGS.use_bfloat16:
                logits = tf.cast(logits, tf.float32)
            all_probs = tf.nn.softmax(logits)
            probs = tf.math.reduce_mean(all_probs, axis=[0, 1])  # marginalize

            # Negative log marginal likelihood computed in a numerically-stable way.
            labels_broadcasted = tf.broadcast_to(
                labels,
                [FLAGS.num_eval_samples, FLAGS.ensemble_size, labels.shape[0]])
            log_likelihoods = -tf.keras.losses.sparse_categorical_crossentropy(
                labels_broadcasted, logits, from_logits=True)
            negative_log_likelihood = tf.reduce_mean(
                -tf.reduce_logsumexp(log_likelihoods, axis=[0, 1]) +
                tf.math.log(float(FLAGS.num_eval_samples *
                                  FLAGS.ensemble_size)))

            l2_loss = compute_l2_loss(model)
            kl = sum(model.losses) / IMAGENET_VALIDATION_IMAGES
            elbo = -(negative_log_likelihood + l2_loss + kl)

            if dataset_name == 'clean':
                if FLAGS.ensemble_size > 1:
                    per_probs = tf.reduce_mean(all_probs,
                                               axis=0)  # marginalize samples
                    diversity_results = um.average_pairwise_diversity(
                        per_probs, FLAGS.ensemble_size)
                    for k, v in diversity_results.items():
                        test_diversity['test/' + k].update_state(v)
                    for i in range(FLAGS.ensemble_size):
                        member_probs = per_probs[i]
                        member_loss = tf.keras.losses.sparse_categorical_crossentropy(
                            labels, member_probs)
                        metrics['test/nll_member_{}'.format(i)].update_state(
                            member_loss)
                        metrics['test/accuracy_member_{}'.format(
                            i)].update_state(labels, member_probs)

                metrics['test/negative_log_likelihood'].update_state(
                    negative_log_likelihood)
                metrics['test/kl'].update_state(kl)
                metrics['test/elbo'].update_state(elbo)
                metrics['test/accuracy'].update_state(labels, probs)
                metrics['test/ece'].update_state(labels, probs)
            else:
                corrupt_metrics['test/nll_{}'.format(
                    dataset_name)].update_state(negative_log_likelihood)
                corrupt_metrics['test/kl_{}'.format(
                    dataset_name)].update_state(kl)
                corrupt_metrics['test/elbo_{}'.format(
                    dataset_name)].update_state(elbo)
                corrupt_metrics['test/accuracy_{}'.format(
                    dataset_name)].update_state(labels, probs)
                corrupt_metrics['test/ece_{}'.format(
                    dataset_name)].update_state(labels, probs)

        strategy.run(step_fn, args=(next(iterator), ))

    train_iterator = iter(train_dataset)
    start_time = time.time()

    for epoch in range(initial_epoch, FLAGS.train_epochs):
        logging.info('Starting to run epoch: %s', epoch)
        for step in range(steps_per_epoch):
            train_step(train_iterator)

            current_step = epoch * steps_per_epoch + (step + 1)
            max_steps = steps_per_epoch * FLAGS.train_epochs
            time_elapsed = time.time() - start_time
            steps_per_sec = float(current_step) / time_elapsed
            eta_seconds = (max_steps - current_step) / steps_per_sec
            message = ('{:.1%} completion: epoch {:d}/{:d}. {:.1f} steps/s. '
                       'ETA: {:.0f} min. Time elapsed: {:.0f} min'.format(
                           current_step / max_steps, epoch + 1,
                           FLAGS.train_epochs, steps_per_sec, eta_seconds / 60,
                           time_elapsed / 60))
            if step % 20 == 0:
                logging.info(message)

        datasets_to_evaluate = {'clean': test_datasets['clean']}
        if (FLAGS.corruptions_interval > 0
                and (epoch + 1) % FLAGS.corruptions_interval == 0):
            datasets_to_evaluate = test_datasets
        for dataset_name, test_dataset in datasets_to_evaluate.items():
            logging.info('Testing on dataset %s', dataset_name)
            test_iterator = iter(test_dataset)
            for step in range(steps_per_eval):
                if step % 20 == 0:
                    logging.info('Starting to run eval step %s of epoch: %s',
                                 step, epoch)
                test_step(test_iterator, dataset_name)
            logging.info('Done with testing on %s', dataset_name)

        corrupt_results = {}
        if (FLAGS.corruptions_interval > 0
                and (epoch + 1) % FLAGS.corruptions_interval == 0):
            corrupt_results = utils.aggregate_corrupt_metrics(
                corrupt_metrics, corruption_types, max_intensity,
                FLAGS.alexnet_errors_path)

        logging.info('Train Loss: %.4f, Accuracy: %.2f%%',
                     metrics['train/loss'].result(),
                     metrics['train/accuracy'].result() * 100)
        logging.info('Test NLL: %.4f, Accuracy: %.2f%%',
                     metrics['test/negative_log_likelihood'].result(),
                     metrics['test/accuracy'].result() * 100)

        for i in range(FLAGS.ensemble_size):
            logging.info(
                'Member %d Test Loss: %.4f, Accuracy: %.2f%%', i,
                metrics['test/nll_member_{}'.format(i)].result(),
                metrics['test/accuracy_member_{}'.format(i)].result() * 100)

        total_metrics = metrics.copy()
        total_metrics.update(training_diversity)
        total_metrics.update(test_diversity)
        total_results = {
            name: metric.result()
            for name, metric in total_metrics.items()
        }
        total_results.update(corrupt_results)
        with summary_writer.as_default():
            for name, result in total_results.items():
                tf.summary.scalar(name, result, step=epoch + 1)

        for metric in total_metrics.values():
            metric.reset_states()

        if (FLAGS.checkpoint_interval > 0
                and (epoch + 1) % FLAGS.checkpoint_interval == 0):
            checkpoint_name = checkpoint.save(
                os.path.join(FLAGS.output_dir, 'checkpoint'))
            logging.info('Saved checkpoint to %s', checkpoint_name)

    final_checkpoint_name = checkpoint.save(
        os.path.join(FLAGS.output_dir, 'checkpoint'))
    logging.info('Saved last checkpoint to %s', final_checkpoint_name)