"""TensorFlow ops for deep neural networks."""
#  Copyright 2015-present The Scikit Flow 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
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from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

from tensorflow.python.ops import nn
from tensorflow.python.ops import rnn_cell
from tensorflow.python.ops import variable_scope as vs
from tensorflow.contrib.learn.python.learn.ops import dropout_ops


def dnn(tensor_in, hidden_units, activation=nn.relu, dropout=None):
  """Creates fully connected deep neural network subgraph.

  Args:
    tensor_in: tensor or placeholder for input features.
    hidden_units: list of counts of hidden units in each layer.
    activation: activation function between layers. Can be None.
    dropout: if not None, will add a dropout layer with given probability.

  Returns:
    A tensor which would be a deep neural network.
  """
  with vs.variable_scope('dnn'):
    for i, n_units in enumerate(hidden_units):
      with vs.variable_scope('layer%d' % i):
        tensor_in = rnn_cell.linear(tensor_in, n_units, True)
        if activation is not None:
          tensor_in = activation(tensor_in)
        if dropout is not None:
          tensor_in = dropout_ops.dropout(tensor_in, prob=(1.0 - dropout))
    return tensor_in
