# Copyright 2017 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""A multivariate TFTS example.

Fits a multivariate model, exports it, and visualizes the learned correlations
by iteratively predicting and sampling from the predictions.
"""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

from os import path
import tempfile

import numpy
import tensorflow as tf

try:
  import matplotlib  # pylint: disable=g-import-not-at-top
  matplotlib.use("TkAgg")  # Need Tk for interactive plots.
  from matplotlib import pyplot  # pylint: disable=g-import-not-at-top
  HAS_MATPLOTLIB = True
except ImportError:
  # Plotting requires matplotlib, but the unit test running this code may
  # execute in an environment without it (i.e. matplotlib is not a build
  # dependency). We'd still like to test the TensorFlow-dependent parts of this
  # example, namely train_and_predict.
  HAS_MATPLOTLIB = False

_MODULE_PATH = path.dirname(__file__)
_DATA_FILE = path.join(_MODULE_PATH, "data/multivariate_level.csv")


def multivariate_train_and_sample(
    csv_file_name=_DATA_FILE, export_directory=None, training_steps=500):
  """Trains, evaluates, and exports a multivariate model."""
  estimator = tf.contrib.timeseries.StructuralEnsembleRegressor(
      periodicities=[], num_features=5)
  reader = tf.contrib.timeseries.CSVReader(
      csv_file_name,
      column_names=((tf.contrib.timeseries.TrainEvalFeatures.TIMES,)
                    + (tf.contrib.timeseries.TrainEvalFeatures.VALUES,) * 5))
  train_input_fn = tf.contrib.timeseries.RandomWindowInputFn(
      # Larger window sizes generally produce a better covariance matrix.
      reader, batch_size=4, window_size=64)
  estimator.train(input_fn=train_input_fn, steps=training_steps)
  evaluation_input_fn = tf.contrib.timeseries.WholeDatasetInputFn(reader)
  current_state = estimator.evaluate(input_fn=evaluation_input_fn, steps=1)
  values = [current_state["observed"]]
  times = [current_state[tf.contrib.timeseries.FilteringResults.TIMES]]
  # Export the model so we can do iterative prediction and filtering without
  # reloading model checkpoints.
  if export_directory is None:
    export_directory = tempfile.mkdtemp()
  input_receiver_fn = estimator.build_raw_serving_input_receiver_fn()
  export_location = estimator.export_saved_model(export_directory,
                                                 input_receiver_fn)
  with tf.Graph().as_default():
    numpy.random.seed(1)  # Make the example a bit more deterministic
    with tf.Session() as session:
      signatures = tf.saved_model.loader.load(
          session, [tf.saved_model.tag_constants.SERVING], export_location)
      for _ in range(100):
        current_prediction = (
            tf.contrib.timeseries.saved_model_utils.predict_continuation(
                continue_from=current_state, signatures=signatures,
                session=session, steps=1))
        next_sample = numpy.random.multivariate_normal(
            # Squeeze out the batch and series length dimensions (both 1).
            mean=numpy.squeeze(current_prediction["mean"], axis=(0, 1)),
            cov=numpy.squeeze(current_prediction["covariance"], axis=(0, 1)))
        # Update model state so that future predictions are conditional on the
        # value we just sampled.
        filtering_features = {
            tf.contrib.timeseries.TrainEvalFeatures.TIMES: current_prediction[
                tf.contrib.timeseries.FilteringResults.TIMES],
            tf.contrib.timeseries.TrainEvalFeatures.VALUES: next_sample[
                None, None, :]}
        current_state = (
            tf.contrib.timeseries.saved_model_utils.filter_continuation(
                continue_from=current_state,
                session=session,
                signatures=signatures,
                features=filtering_features))
        values.append(next_sample[None, None, :])
        times.append(current_state["times"])
  all_observations = numpy.squeeze(numpy.concatenate(values, axis=1), axis=0)
  all_times = numpy.squeeze(numpy.concatenate(times, axis=1), axis=0)
  return all_times, all_observations


def main(unused_argv):
  if not HAS_MATPLOTLIB:
    raise ImportError(
        "Please install matplotlib to generate a plot from this example.")
  all_times, all_observations = multivariate_train_and_sample()
  # Show where sampling starts on the plot
  pyplot.axvline(1000, linestyle="dotted")
  pyplot.plot(all_times, all_observations)
  pyplot.show()


if __name__ == "__main__":
  tf.app.run(main=main)
