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Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
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 http://www.apache.org/licenses/LICENSE-2.0  

Unless required by applicable law or agreed to in writing, software
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# Get the dependency .py files, if any.
! git clone https://github.com/GoogleCloudPlatform/cloudml-samples.git
! cp cloudml-samples/tpu/templates/tpu_lstm_keras/* .

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import argparse
import os
import numpy as np
import tensorflow as tf
from tensorflow.keras.layers import LSTM

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def build_model():
    inputs = tf.keras.Input(shape=(5, 3))
    encoded = tf.keras.layers.LSTM(10)(inputs)
    outputs = tf.keras.layers.Dense(1, activation=tf.nn.sigmoid)(encoded)

    model = tf.keras.Model(inputs=inputs, outputs=outputs)

    return model

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def train_input_fn():
    batch_size = 16

    # make some fake data
    x = np.random.rand(100, 5, 3)
    y = np.random.rand(100, 1)

    # TPUs currently do not support float64
    x_tensor = tf.constant(x, dtype=tf.float32)
    y_tensor = tf.constant(y, dtype=tf.float32)

    # create tf.data.Dataset
    dataset = tf.data.Dataset.from_tensor_slices((x_tensor, y_tensor))

    dataset = dataset.repeat().shuffle(32).batch(batch_size, drop_remainder=True)

    # TPUs need to know all dimensions when the graph is built
    # Datasets know the batch size only when the graph is run
    def set_shapes(features, labels):
        features_shape = features.get_shape().merge_with([batch_size, None, None])
        labels_shape = labels.get_shape().merge_with([batch_size, None])

        features.set_shape(features_shape)
        labels.set_shape(labels_shape)

        return features, labels

    dataset = dataset.map(set_shapes)
    dataset = dataset.prefetch(tf.contrib.data.AUTOTUNE)

    return dataset

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def main(args):
    model = build_model()

    if args.use_tpu:
        # distribute over TPU cores
        # Note: This requires TensorFlow 1.11
        tpu_cluster_resolver = tf.contrib.cluster_resolver.TPUClusterResolver(args.tpu)
        strategy = tf.contrib.tpu.TPUDistributionStrategy(tpu_cluster_resolver)
        model = tf.contrib.tpu.keras_to_tpu_model(
            model, strategy=strategy)

    optimizer = tf.train.RMSPropOptimizer(learning_rate=0.05)
    loss_fn = tf.losses.log_loss
    model.compile(optimizer, loss_fn)

    model.fit(train_input_fn, epochs=3, steps_per_epoch=10)

    if not os.path.exists(args.model_dir):
        os.makedirs(args.model_dir)
    model.save(os.path.join(args.model_dir, 'model.hd5'))

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parser = argparse.ArgumentParser()

parser.add_argument(
    '--model-dir',
    type=str,
    default='/tmp/tpu-template',
    help='Location to write checkpoints and summaries to.  Must be a GCS URI when using Cloud TPU.')
parser.add_argument(
    '--use-tpu',
    action='store_true',
    help='Whether to use TPU.')
parser.add_argument(
    '--tpu',
    default=None,
    help='The name or GRPC URL of the TPU node.  Leave it as `None` when training on CMLE.')

args, _ = parser.parse_known_args()

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# TODO(user): change this
args.model_dir = 'gs://your-gcs-bucket'

# Get hostname from environment using ipython magic.
# This returns a list.
hostname = !hostname

args.tpu = hostname[0]
args.use_tpu = True

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# Use gcloud command line tool to create a TPU in the same zone as the VM instance.
! gcloud compute tpus create `hostname` \
  --zone `gcloud compute instances list --filter="name=$(hostname)" --format 'csv[no-heading](zone)'`\
  --network default \
  --range 10.101.1.0 \
  --version 1.13

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main(args)

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# Use gcloud command line tool to delete the TPU.
! gcloud compute tpus delete `hostname` \
  --zone `gcloud compute instances list --filter="name=$(hostname)" --format 'csv[no-heading](zone)'`\
  --quiet