{"cells":[{"metadata":{},"cell_type":"markdown","source":"**This notebooks shows three ways of training a model on TPU:**\n1. Using Keras and model.fit()\n1. Using a custom training loop\n1. Using a custom training loop specifically optimized for TPU\n\n**Optimization that benefit all three models:**\n\n- use `dataset.batch(BATCH_SIZE, drop_remainder=True)`<br/>\n   The training dataset is infinitely repeated so drop_remainder=True should not be needed. However, whith the setting, Tensorflow produces batches of a known size and although XLA (the TPU compiler) can now handle variable batches, it is slightly faster on fixed batches.<br/>\n   On the validation dataset, this setting can drop some validation images. It is not the case here because the validation dataset happens to contain an integer number of batches.\n- For some reason, I had to multiply the learning rate schedule by 8 in custom training loops. Convergence would differ from model.fit otherwise. Investigating...\n   \n**Optimizations specific to the TPU-optimized custom training loop:**\n\n- The training and validation step functions run multiple batches at once. This is achieved by placing a loop using `tf.range()` in the step function. The loop will be compiled to (thanks to `@tf.function`) and executed on TPU.\n- The validation dataset is made to repeat indefinitely because handling end-of-dataset exception in a TPU loop implemented with `tf.range()` is not yet possible. Validation is adjusted to always use exactly or more than the entire validation dataset. This could change numerics. It happens that in this example, the validation dataset is used exactly once per validation.\n- The validation dataset iterator is not reset between validation runs. Since the iterator is passed into the step function which is then compiled for TPU (thanks to `@tf.function`), passing a fresh iterator for every validation run would trigger a fresh recompilation. With a validation at the end of every epoch this would be slow.\n- Losses are reported through Keras metrics. It is possible to return values from step function and return losses in that way. However, in the optimized version of the custom training loop, using `tf.range()`, aggregating losses returned from multiple batches becomes impractical."},{"metadata":{"_cell_guid":"b1076dfc-b9ad-4769-8c92-a6c4dae69d19","_uuid":"8f2839f25d086af736a60e9eeb907d3b93b6e0e5","trusted":true},"cell_type":"code","source":"import math, re, os, time\nimport tensorflow as tf\nimport numpy as np\nfrom collections import namedtuple\nfrom matplotlib import pyplot as plt\nfrom kaggle_datasets import KaggleDatasets\nfrom sklearn.metrics import f1_score, precision_score, recall_score, confusion_matrix\nprint(\"Tensorflow version \" + tf.__version__)\nAUTO = tf.data.experimental.AUTOTUNE","execution_count":null,"outputs":[]},{"metadata":{},"cell_type":"markdown","source":"# TPU or GPU detection"},{"metadata":{"trusted":true},"cell_type":"code","source":"# Detect hardware, return appropriate distribution strategy\ntry:\n    tpu = tf.distribute.cluster_resolver.TPUClusterResolver()  # TPU detection. No parameters necessary if TPU_NAME environment variable is set. On Kaggle this is always the case.\n    print('Running on TPU ', tpu.master())\nexcept ValueError:\n    tpu = None\n\nif tpu:\n    tf.config.experimental_connect_to_cluster(tpu)\n    tf.tpu.experimental.initialize_tpu_system(tpu)\n    strategy = tf.distribute.experimental.TPUStrategy(tpu)\nelse:\n    strategy = tf.distribute.get_strategy() # default distribution strategy in Tensorflow. Works on CPU and single GPU.\n\nprint(\"REPLICAS: \", strategy.num_replicas_in_sync)","execution_count":null,"outputs":[]},{"metadata":{},"cell_type":"markdown","source":"# Competition data access\nTPUs read data directly from Google Cloud Storage (GCS). This Kaggle utility will copy the dataset to a GCS bucket co-located with the TPU. If you have multiple datasets attached to the notebook, you can pass the name of a specific dataset to the get_gcs_path function. The name of the dataset is the name of the directory it is mounted in. Use `!ls /kaggle/input/` to list attached datasets."},{"metadata":{"trusted":true},"cell_type":"code","source":"GCS_DS_PATH = KaggleDatasets().get_gcs_path() # you can list the bucket with \"!gsutil ls $GCS_DS_PATH\"","execution_count":null,"outputs":[]},{"metadata":{},"cell_type":"markdown","source":"# Configuration"},{"metadata":{"trusted":true},"cell_type":"code","source":"IMAGE_SIZE = [512, 512] # At this size, a GPU will run out of memory. Use the TPU.\n                        # For GPU training, please select 224 x 224 px image size.\nEPOCHS = 12\nBATCH_SIZE = 16 * strategy.num_replicas_in_sync\n\nGCS_PATH_SELECT = { # available image sizes\n    192: GCS_DS_PATH + '/tfrecords-jpeg-192x192',\n    224: GCS_DS_PATH + '/tfrecords-jpeg-224x224',\n    331: GCS_DS_PATH + '/tfrecords-jpeg-331x331',\n    512: GCS_DS_PATH + '/tfrecords-jpeg-512x512'\n}\nGCS_PATH = GCS_PATH_SELECT[IMAGE_SIZE[0]]\n\nTRAINING_FILENAMES = tf.io.gfile.glob(GCS_PATH + '/train/*.tfrec')\nVALIDATION_FILENAMES = tf.io.gfile.glob(GCS_PATH + '/val/*.tfrec')\nTEST_FILENAMES = tf.io.gfile.glob(GCS_PATH + '/test/*.tfrec') # predictions on this dataset should be submitted for the competition\n\nCLASSES = ['pink primrose',    'hard-leaved pocket orchid', 'canterbury bells', 'sweet pea',     'wild geranium',     'tiger lily',           'moon orchid',              'bird of paradise', 'monkshood',        'globe thistle',         # 00 - 09\n           'snapdragon',       \"colt's foot\",               'king protea',      'spear thistle', 'yellow iris',       'globe-flower',         'purple coneflower',        'peruvian lily',    'balloon flower',   'giant white arum lily', # 10 - 19\n           'fire lily',        'pincushion flower',         'fritillary',       'red ginger',    'grape hyacinth',    'corn poppy',           'prince of wales feathers', 'stemless gentian', 'artichoke',        'sweet william',         # 20 - 29\n           'carnation',        'garden phlox',              'love in the mist', 'cosmos',        'alpine sea holly',  'ruby-lipped cattleya', 'cape flower',              'great masterwort', 'siam tulip',       'lenten rose',           # 30 - 39\n           'barberton daisy',  'daffodil',                  'sword lily',       'poinsettia',    'bolero deep blue',  'wallflower',           'marigold',                 'buttercup',        'daisy',            'common dandelion',      # 40 - 49\n           'petunia',          'wild pansy',                'primula',          'sunflower',     'lilac hibiscus',    'bishop of llandaff',   'gaura',                    'geranium',         'orange dahlia',    'pink-yellow dahlia',    # 50 - 59\n           'cautleya spicata', 'japanese anemone',          'black-eyed susan', 'silverbush',    'californian poppy', 'osteospermum',         'spring crocus',            'iris',             'windflower',       'tree poppy',            # 60 - 69\n           'gazania',          'azalea',                    'water lily',       'rose',          'thorn apple',       'morning glory',        'passion flower',           'lotus',            'toad lily',        'anthurium',             # 70 - 79\n           'frangipani',       'clematis',                  'hibiscus',         'columbine',     'desert-rose',       'tree mallow',          'magnolia',                 'cyclamen ',        'watercress',       'canna lily',            # 80 - 89\n           'hippeastrum ',     'bee balm',                  'pink quill',       'foxglove',      'bougainvillea',     'camellia',             'mallow',                   'mexican petunia',  'bromelia',         'blanket flower',        # 90 - 99\n           'trumpet creeper',  'blackberry lily',           'common tulip',     'wild rose']                                                                                                                                               # 100 - 102\n\n# Learning rate schedule for TPU, GPU and CPU.\n# Using an LR ramp up because fine-tuning a pre-trained model.\n# Starting with a high LR would break the pre-trained weights.\n\nLR_START = 0.00001\nLR_MAX = 0.00005 * strategy.num_replicas_in_sync\nLR_MIN = 0.00001\nLR_RAMPUP_EPOCHS = 5\nLR_SUSTAIN_EPOCHS = 0\nLR_EXP_DECAY = .8\n\n# in custom training loop training you need an object to hold the epoch value\nclass LRSchedule(tf.keras.optimizers.schedules.LearningRateSchedule):\n    \n    def __init__(self):\n        \n        super(LRSchedule, self).__init__()\n                    \n    def __call__(self, step):\n\n        epoch = step // STEPS_PER_EPOCH\n    \n        c1 = epoch < LR_RAMPUP_EPOCHS        \n        c2 = tf.math.logical_and(epoch < LR_RAMPUP_EPOCHS + LR_SUSTAIN_EPOCHS, epoch >= LR_RAMPUP_EPOCHS)\n        c3 = epoch >= LR_RAMPUP_EPOCHS + LR_SUSTAIN_EPOCHS\n        \n        lr1 = (LR_MAX - LR_START) / LR_RAMPUP_EPOCHS * epoch + LR_START\n        lr2 = LR_MAX\n        lr3 = (LR_MAX - LR_MIN) * LR_EXP_DECAY**(epoch - LR_RAMPUP_EPOCHS - LR_SUSTAIN_EPOCHS) + LR_MIN\n    \n        lr = tf.cast(c1, dtype=tf.float32) * lr1 + tf.cast(c2, dtype=tf.float32) * lr2 + tf.cast(c3, dtype=tf.float32) * lr3\n    \n        return lr       \n    \n    \nlr_schedule = LRSchedule()\nrng = [i for i in range(EPOCHS)]\ny = [lr_schedule(x * STEPS_PER_EPOCH) for x in rng]\nplt.plot(rng, y)\nprint(\"Learning rate schedule: {:.3g} to {:.3g} to {:.3g}\".format(y[0], max(y), y[-1]))","execution_count":null,"outputs":[]},{"metadata":{},"cell_type":"markdown","source":"## Visualization utilities\ndata -> pixels, nothing of much interest for the machine learning practitioner in this section."},{"metadata":{"trusted":true},"cell_type":"code","source":"# numpy and matplotlib defaults\nnp.set_printoptions(threshold=15, linewidth=80)\n\ndef batch_to_numpy_images_and_labels(data):\n    images, labels = data\n    numpy_images = images.numpy()\n    numpy_labels = labels.numpy()\n    if numpy_labels.dtype == object: # binary string in this case, these are image ID strings\n        numpy_labels = [None for _ in enumerate(numpy_images)]\n    # If no labels, only image IDs, return None for labels (this is the case for test data)\n    return numpy_images, numpy_labels\n\ndef title_from_label_and_target(label, correct_label):\n    if correct_label is None:\n        return CLASSES[label], True\n    correct = (label == correct_label)\n    return \"{} [{}{}{}]\".format(CLASSES[label], 'OK' if correct else 'NO', u\"\\u2192\" if not correct else '',\n                                CLASSES[correct_label] if not correct else ''), correct\n\ndef display_one_flower(image, title, subplot, red=False, titlesize=16):\n    plt.subplot(*subplot)\n    plt.axis('off')\n    plt.imshow(image)\n    if len(title) > 0:\n        plt.title(title, fontsize=int(titlesize) if not red else int(titlesize/1.2), color='red' if red else 'black', fontdict={'verticalalignment':'center'}, pad=int(titlesize/1.5))\n    return (subplot[0], subplot[1], subplot[2]+1)\n    \ndef display_batch_of_images(databatch, predictions=None):\n    \"\"\"This will work with:\n    display_batch_of_images(images)\n    display_batch_of_images(images, predictions)\n    display_batch_of_images((images, labels))\n    display_batch_of_images((images, labels), predictions)\n    \"\"\"\n    # data\n    images, labels = batch_to_numpy_images_and_labels(databatch)\n    if labels is None:\n        labels = [None for _ in enumerate(images)]\n        \n    # auto-squaring: this will drop data that does not fit into square or square-ish rectangle\n    rows = int(math.sqrt(len(images)))\n    cols = len(images)//rows\n        \n    # size and spacing\n    FIGSIZE = 13.0\n    SPACING = 0.1\n    subplot=(rows,cols,1)\n    if rows < cols:\n        plt.figure(figsize=(FIGSIZE,FIGSIZE/cols*rows))\n    else:\n        plt.figure(figsize=(FIGSIZE/rows*cols,FIGSIZE))\n    \n    # display\n    for i, (image, label) in enumerate(zip(images[:rows*cols], labels[:rows*cols])):\n        title = '' if label is None else CLASSES[label]\n        correct = True\n        if predictions is not None:\n            title, correct = title_from_label_and_target(predictions[i], label)\n        dynamic_titlesize = FIGSIZE*SPACING/max(rows,cols)*40+3 # magic formula tested to work from 1x1 to 10x10 images\n        subplot = display_one_flower(image, title, subplot, not correct, titlesize=dynamic_titlesize)\n    \n    #layout\n    plt.tight_layout()\n    if label is None and predictions is None:\n        plt.subplots_adjust(wspace=0, hspace=0)\n    else:\n        plt.subplots_adjust(wspace=SPACING, hspace=SPACING)\n    plt.show()\n\ndef display_confusion_matrix(cmat, score, precision, recall):\n    plt.figure(figsize=(15,15))\n    ax = plt.gca()\n    ax.matshow(cmat, cmap='Reds')\n    ax.set_xticks(range(len(CLASSES)))\n    ax.set_xticklabels(CLASSES, fontdict={'fontsize': 7})\n    plt.setp(ax.get_xticklabels(), rotation=45, ha=\"left\", rotation_mode=\"anchor\")\n    ax.set_yticks(range(len(CLASSES)))\n    ax.set_yticklabels(CLASSES, fontdict={'fontsize': 7})\n    plt.setp(ax.get_yticklabels(), rotation=45, ha=\"right\", rotation_mode=\"anchor\")\n    titlestring = \"\"\n    if score is not None:\n        titlestring += 'f1 = {:.3f} '.format(score)\n    if precision is not None:\n        titlestring += '\\nprecision = {:.3f} '.format(precision)\n    if recall is not None:\n        titlestring += '\\nrecall = {:.3f} '.format(recall)\n    if len(titlestring) > 0:\n        ax.text(101, 1, titlestring, fontdict={'fontsize': 18, 'horizontalalignment':'right', 'verticalalignment':'top', 'color':'#804040'})\n    plt.show()\n    \ndef display_training_curves(training, validation, title, subplot):\n    if subplot%10==1: # set up the subplots on the first call\n        plt.subplots(figsize=(10,10), facecolor='#F0F0F0')\n        plt.tight_layout()\n    ax = plt.subplot(subplot)\n    ax.set_facecolor('#F8F8F8')\n    ax.plot(training)\n    ax.plot(validation)\n    ax.set_title('model '+ title)\n    ax.set_ylabel(title)\n    #ax.set_ylim(0.28,1.05)\n    ax.set_xlabel('epoch')\n    ax.legend(['train', 'valid.'])","execution_count":null,"outputs":[]},{"metadata":{},"cell_type":"markdown","source":"# Datasets"},{"metadata":{"_cell_guid":"79c7e3d0-c299-4dcb-8224-4455121ee9b0","_uuid":"d629ff2d2480ee46fbb7e2d37f6b5fab8052498a","trusted":true},"cell_type":"code","source":"def decode_image(image_data):\n    image = tf.image.decode_jpeg(image_data, channels=3)\n    image = tf.cast(image, tf.float32) / 255.0  # convert image to floats in [0, 1] range\n    image = tf.reshape(image, [*IMAGE_SIZE, 3]) # explicit size needed for TPU\n    return image\n\ndef read_labeled_tfrecord(example):\n    LABELED_TFREC_FORMAT = {\n        \"image\": tf.io.FixedLenFeature([], tf.string), # tf.string means bytestring\n        \"class\": tf.io.FixedLenFeature([], tf.int64),  # shape [] means single element\n    }\n    example = tf.io.parse_single_example(example, LABELED_TFREC_FORMAT)\n    image = decode_image(example['image'])\n    label = tf.cast(example['class'], tf.int32)\n    return image, label # returns a dataset of (image, label) pairs\n\ndef read_unlabeled_tfrecord(example):\n    UNLABELED_TFREC_FORMAT = {\n        \"image\": tf.io.FixedLenFeature([], tf.string), # tf.string means bytestring\n        \"id\": tf.io.FixedLenFeature([], tf.string),  # shape [] means single element\n        # class is missing, this competitions's challenge is to predict flower classes for the test dataset\n    }\n    example = tf.io.parse_single_example(example, UNLABELED_TFREC_FORMAT)\n    image = decode_image(example['image'])\n    idnum = example['id']\n    return image, idnum # returns a dataset of image(s)\n\ndef load_dataset(filenames, labeled=True, ordered=False):\n    # Read from TFRecords. For optimal performance, reading from multiple files at once and\n    # disregarding data order. Order does not matter since we will be shuffling the data anyway.\n\n    ignore_order = tf.data.Options()\n    if not ordered:\n        ignore_order.experimental_deterministic = False # disable order, increase speed\n\n    dataset = tf.data.TFRecordDataset(filenames, num_parallel_reads=AUTO) # automatically interleaves reads from multiple files\n    dataset = dataset.with_options(ignore_order) # uses data as soon as it streams in, rather than in its original order\n    dataset = dataset.map(read_labeled_tfrecord if labeled else read_unlabeled_tfrecord, num_parallel_calls=AUTO)\n    # returns a dataset of (image, label) pairs if labeled=True or (image, id) pairs if labeled=False\n    return dataset\n\ndef data_augment(image, label):\n    # data augmentation. Thanks to the dataset.prefetch(AUTO) statement in the next function (below),\n    # this happens essentially for free on TPU. Data pipeline code is executed on the \"CPU\" part\n    # of the TPU while the TPU itself is computing gradients.\n    image = tf.image.random_flip_left_right(image)\n    #image = tf.image.random_saturation(image, 0, 2)\n    return image, label   \n\ndef get_training_dataset():\n    dataset = load_dataset(TRAINING_FILENAMES, labeled=True)\n    dataset = dataset.map(data_augment, num_parallel_calls=AUTO)\n    dataset = dataset.repeat() # the training dataset must repeat for several epochs\n    dataset = dataset.shuffle(2048)\n    dataset = dataset.batch(BATCH_SIZE, drop_remainder=True) # slighly faster with fixed tensor sizes\n    dataset = dataset.prefetch(AUTO) # prefetch next batch while training (autotune prefetch buffer size)\n    return dataset\n\ndef get_validation_dataset(ordered=False, repeated=False):\n    dataset = load_dataset(VALIDATION_FILENAMES, labeled=True, ordered=ordered)\n    if repeated:\n        dataset = dataset.repeat()\n        dataset = dataset.shuffle(2048)\n    dataset = dataset.batch(BATCH_SIZE, drop_remainder=repeated) # slighly faster with fixed tensor sizes\n    dataset = dataset.cache()\n    dataset = dataset.prefetch(AUTO) # prefetch next batch while training (autotune prefetch buffer size)\n    return dataset\n\ndef get_test_dataset(ordered=False):\n    dataset = load_dataset(TEST_FILENAMES, labeled=False, ordered=ordered)\n    dataset = dataset.batch(BATCH_SIZE)\n    dataset = dataset.prefetch(AUTO) # prefetch next batch while training (autotune prefetch buffer size)\n    return dataset\n\ndef count_data_items(filenames):\n    # the number of data items is written in the name of the .tfrec files, i.e. flowers00-230.tfrec = 230 data items\n    n = [int(re.compile(r\"-([0-9]*)\\.\").search(filename).group(1)) for filename in filenames]\n    return np.sum(n)\n\ndef int_div_round_up(a, b):\n    return (a + b - 1) // b\n\nNUM_TRAINING_IMAGES = count_data_items(TRAINING_FILENAMES)\nNUM_VALIDATION_IMAGES = count_data_items(VALIDATION_FILENAMES)\nNUM_TEST_IMAGES = count_data_items(TEST_FILENAMES)\nSTEPS_PER_EPOCH = NUM_TRAINING_IMAGES // BATCH_SIZE\nVALIDATION_STEPS = int_div_round_up(NUM_VALIDATION_IMAGES, BATCH_SIZE)\nprint('Dataset: {} training images, {} validation images, {} unlabeled test images'.format(NUM_TRAINING_IMAGES, NUM_VALIDATION_IMAGES, NUM_TEST_IMAGES))","execution_count":null,"outputs":[]},{"metadata":{},"cell_type":"markdown","source":"# Dataset visualizations"},{"metadata":{"trusted":true},"cell_type":"code","source":"# Peek at training data\ntraining_dataset = get_training_dataset()\ntraining_dataset = training_dataset.unbatch().batch(20)\ntrain_batch = iter(training_dataset)","execution_count":null,"outputs":[]},{"metadata":{"trusted":true},"cell_type":"code","source":"# run this cell again for next set of images\ndisplay_batch_of_images(next(train_batch))","execution_count":null,"outputs":[]},{"metadata":{"trusted":true},"cell_type":"code","source":"# peer at test data\ntest_dataset = get_test_dataset()\ntest_dataset = test_dataset.unbatch().batch(20)\ntest_batch = iter(test_dataset)","execution_count":null,"outputs":[]},{"metadata":{"trusted":true},"cell_type":"code","source":"# run this cell again for next set of images\ndisplay_batch_of_images(next(test_batch))","execution_count":null,"outputs":[]},{"metadata":{},"cell_type":"markdown","source":"# Custom training loop\n## Model"},{"metadata":{"trusted":true},"cell_type":"code","source":"with strategy.scope():\n    pretrained_model = tf.keras.applications.Xception(weights='imagenet', include_top=False ,input_shape=[*IMAGE_SIZE, 3])\n    pretrained_model.trainable = True # False = transfer learning, True = fine-tuning\n    \n    model = tf.keras.Sequential([\n        pretrained_model,\n        tf.keras.layers.GlobalAveragePooling2D(),\n        tf.keras.layers.Dense(len(CLASSES), activation='softmax')\n    ])\n    model.summary()\n    \n    # Instiate optimizer and metrics\n    lr_schedule = LRSchedule()\n    optimizer = tf.keras.optimizers.Adam(learning_rate=lr_schedule) # not quite sure yet why LR must be scaled up by 8 (otherwise, does not converge the same)\n    train_accuracy = tf.keras.metrics.SparseCategoricalAccuracy()\n    valid_accuracy = tf.keras.metrics.SparseCategoricalAccuracy()\n    train_loss = tf.keras.metrics.Sum()\n    valid_loss = tf.keras.metrics.Sum()\n    \n    loss_fn = lambda a,b: tf.nn.compute_average_loss(tf.keras.losses.sparse_categorical_crossentropy(a,b), global_batch_size=BATCH_SIZE)","execution_count":null,"outputs":[]},{"metadata":{},"cell_type":"markdown","source":"## Step functions"},{"metadata":{"trusted":true},"cell_type":"code","source":"@tf.function\ndef train_step(images, labels):\n    with tf.GradientTape() as tape:\n        probabilities = model(images, training=True)\n        loss = loss_fn(labels, probabilities)\n    grads = tape.gradient(loss, model.trainable_variables)\n    optimizer.apply_gradients(zip(grads, model.trainable_variables))\n        \n    # update metrics\n    train_accuracy.update_state(labels, probabilities)\n    train_loss.update_state(loss)\n\n@tf.function\ndef valid_step(images, labels):\n    probabilities = model(images, training=False)\n    loss = loss_fn(labels, probabilities)\n    \n    # update metrics\n    valid_accuracy.update_state(labels, probabilities)\n    valid_loss.update_state(loss)","execution_count":null,"outputs":[]},{"metadata":{},"cell_type":"markdown","source":"## Training loop"},{"metadata":{"trusted":true},"cell_type":"code","source":"start_time = epoch_start_time = time.time()\n\n# distribute the datset according to the strategy\ntrain_dist_ds = strategy.experimental_distribute_dataset(get_training_dataset())\nvalid_dist_ds = strategy.experimental_distribute_dataset(get_validation_dataset())\n\nprint(\"Steps per epoch:\", STEPS_PER_EPOCH)\nHistory = namedtuple('History', 'history')\nhistory = History(history={'loss': [], 'val_loss': [], 'sparse_categorical_accuracy': [], 'val_sparse_categorical_accuracy': []})\n\nepoch = 0\n\n\nfor step, (images, labels) in enumerate(train_dist_ds):\n    \n    # run training step\n    strategy.experimental_run_v2(train_step, args=(images, labels))\n    print('=', end='', flush=True)\n\n    # validation run at the end of each epoch\n    if ((step+1) // STEPS_PER_EPOCH) > epoch:\n        print('|', end='', flush=True)\n        \n        # validation run\n        for image, labels in valid_dist_ds:\n            strategy.experimental_run_v2(valid_step, args=(image, labels))\n            print('=', end='', flush=True)\n\n        # compute metrics\n        history.history['sparse_categorical_accuracy'].append(train_accuracy.result().numpy())\n        history.history['val_sparse_categorical_accuracy'].append(valid_accuracy.result().numpy())\n        history.history['loss'].append(train_loss.result().numpy() / STEPS_PER_EPOCH)\n        history.history['val_loss'].append(valid_loss.result().numpy() / VALIDATION_STEPS)\n        \n        # report metrics\n        epoch_time = time.time() - epoch_start_time\n        print('\\nEPOCH {:d}/{:d}'.format(epoch+1, EPOCHS))\n        print('time: {:0.1f}s'.format(epoch_time),\n              'loss: {:0.4f}'.format(history.history['loss'][-1]),\n              'accuracy: {:0.4f}'.format(history.history['sparse_categorical_accuracy'][-1]),\n              'val_loss: {:0.4f}'.format(history.history['val_loss'][-1]),\n              'val_acc: {:0.4f}'.format(history.history['val_sparse_categorical_accuracy'][-1]),\n              'lr: {:0.4g}'.format(lr_schedule(step)), flush=True)\n        \n        # set up next epoch\n        epoch = (step+1) // STEPS_PER_EPOCH\n        epoch_start_time = time.time()\n\n        train_accuracy.reset_states()\n        valid_accuracy.reset_states()\n        valid_loss.reset_states()\n        train_loss.reset_states()\n        \n        if epoch >= EPOCHS:\n            break\n    \nsimple_ctl_training_time = time.time() - start_time\nprint(\"SIMPLE CTL TRAINING TIME: {:0.1f}s\".format(simple_ctl_training_time))","execution_count":null,"outputs":[]}],"metadata":{"kernelspec":{"display_name":"Python 3","language":"python","name":"python3"},"language_info":{"codemirror_mode":{"name":"ipython","version":3},"file_extension":".py","mimetype":"text/x-python","name":"python","nbconvert_exporter":"python","pygments_lexer":"ipython3","version":"3.6.6"}},"nbformat":4,"nbformat_minor":4}