path: root/tensorflow/python/keras/layers/core.py

# Copyright 2015 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.
# ==============================================================================
"""Core Keras layers.
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import copy
import sys
import types as python_types
import warnings

import numpy as np

from tensorflow.python.eager import context
from tensorflow.python.framework import ops
from tensorflow.python.framework import tensor_shape
from tensorflow.python.keras import activations
from tensorflow.python.keras import backend as K
from tensorflow.python.keras import constraints
from tensorflow.python.keras import initializers
from tensorflow.python.keras import regularizers
from tensorflow.python.keras.engine.base_layer import InputSpec
from tensorflow.python.keras.engine.base_layer import Layer
from tensorflow.python.keras.utils import conv_utils
from tensorflow.python.keras.utils import generic_utils
from tensorflow.python.keras.utils import tf_utils
from tensorflow.python.ops import array_ops
from tensorflow.python.ops import gen_math_ops
from tensorflow.python.ops import math_ops
from tensorflow.python.ops import nn
from tensorflow.python.ops import nn_ops
from tensorflow.python.ops import standard_ops
from tensorflow.python.util.tf_export import tf_export


@tf_export('keras.layers.Masking')
class Masking(Layer):
  """Masks a sequence by using a mask value to skip timesteps.

  For each timestep in the input tensor (dimension #1 in the tensor),
  if all values in the input tensor at that timestep
  are equal to `mask_value`, then the timestep will be masked (skipped)
  in all downstream layers (as long as they support masking).

  If any downstream layer does not support masking yet receives such
  an input mask, an exception will be raised.

  Example:

  Consider a Numpy data array `x` of shape `(samples, timesteps, features)`,
  to be fed to an LSTM layer.
  You want to mask timestep #3 and #5 because you lack data for
  these timesteps. You can:

      - set `x[:, 3, :] = 0.` and `x[:, 5, :] = 0.`
      - insert a `Masking` layer with `mask_value=0.` before the LSTM layer:

  ```python
      model = Sequential()
      model.add(Masking(mask_value=0., input_shape=(timesteps, features)))
      model.add(LSTM(32))
  ```
  """

  def __init__(self, mask_value=0., **kwargs):
    super(Masking, self).__init__(**kwargs)
    self.supports_masking = True
    self.mask_value = mask_value

  def compute_mask(self, inputs, mask=None):
    return K.any(math_ops.not_equal(inputs, self.mask_value), axis=-1)

  def call(self, inputs):
    boolean_mask = K.any(
        math_ops.not_equal(inputs, self.mask_value), axis=-1, keepdims=True)
    return inputs * math_ops.cast(boolean_mask, inputs.dtype)

  def compute_output_shape(self, input_shape):
    return input_shape

  def get_config(self):
    config = {'mask_value': self.mask_value}
    base_config = super(Masking, self).get_config()
    return dict(list(base_config.items()) + list(config.items()))


@tf_export('keras.layers.Dropout')
class Dropout(Layer):
  """Applies Dropout to the input.

  Dropout consists in randomly setting
  a fraction `rate` of input units to 0 at each update during training time,
  which helps prevent overfitting.

  Arguments:
      rate: float between 0 and 1. Fraction of the input units to drop.
      noise_shape: 1D integer tensor representing the shape of the
          binary dropout mask that will be multiplied with the input.
          For instance, if your inputs have shape
          `(batch_size, timesteps, features)` and
          you want the dropout mask to be the same for all timesteps,
          you can use `noise_shape=(batch_size, 1, features)`.
      seed: A Python integer to use as random seed.
  """

  def __init__(self, rate, noise_shape=None, seed=None, **kwargs):
    super(Dropout, self).__init__(**kwargs)
    self.rate = rate
    self.noise_shape = noise_shape
    self.seed = seed
    self.supports_masking = True

  def _get_noise_shape(self, inputs):
    # Subclasses of `Dropout` may implement `_get_noise_shape(self, inputs)`,
    # which will override `self.noise_shape`, and allows for custom noise
    # shapes with dynamically sized inputs.
    if self.noise_shape is None:
      return self.noise_shape
    return nn_ops._get_noise_shape(inputs, self.noise_shape)  # pylint: disable=protected-access

  def call(self, inputs, training=None):
    original_training_value = training
    if training is None:
      training = K.learning_phase()

    def dropped_inputs():
      return nn.dropout(inputs, 1  - self.rate,
                        noise_shape=self._get_noise_shape(inputs),
                        seed=self.seed)
    output = tf_utils.smart_cond(training,
                                 dropped_inputs,
                                 lambda: array_ops.identity(inputs))
    # EagerTensor object has no attribute _uses_learning_phase
    if not context.executing_eagerly() and original_training_value is None:
      output._uses_learning_phase = True  # pylint: disable=protected-access
    return output

  def compute_output_shape(self, input_shape):
    return input_shape

  def get_config(self):
    config = {
        'rate': self.rate,
        'noise_shape': self.noise_shape,
        'seed': self.seed
    }
    base_config = super(Dropout, self).get_config()
    return dict(list(base_config.items()) + list(config.items()))


@tf_export('keras.layers.SpatialDropout1D')
class SpatialDropout1D(Dropout):
  """Spatial 1D version of Dropout.

  This version performs the same function as Dropout, however it drops
  entire 1D feature maps instead of individual elements. If adjacent frames
  within feature maps are strongly correlated (as is normally the case in
  early convolution layers) then regular dropout will not regularize the
  activations and will otherwise just result in an effective learning rate
  decrease. In this case, SpatialDropout1D will help promote independence
  between feature maps and should be used instead.

  Arguments:
      rate: float between 0 and 1. Fraction of the input units to drop.

  Input shape:
      3D tensor with shape:
      `(samples, timesteps, channels)`

  Output shape:
      Same as input

  References:
      - [Efficient Object Localization Using Convolutional
        Networks](https://arxiv.org/abs/1411.4280)
  """

  def __init__(self, rate, **kwargs):
    super(SpatialDropout1D, self).__init__(rate, **kwargs)
    self.input_spec = InputSpec(ndim=3)

  def _get_noise_shape(self, inputs):
    input_shape = array_ops.shape(inputs)
    noise_shape = (input_shape[0], 1, input_shape[2])
    return noise_shape


@tf_export('keras.layers.SpatialDropout2D')
class SpatialDropout2D(Dropout):
  """Spatial 2D version of Dropout.

  This version performs the same function as Dropout, however it drops
  entire 2D feature maps instead of individual elements. If adjacent pixels
  within feature maps are strongly correlated (as is normally the case in
  early convolution layers) then regular dropout will not regularize the
  activations and will otherwise just result in an effective learning rate
  decrease. In this case, SpatialDropout2D will help promote independence
  between feature maps and should be used instead.

  Arguments:
      rate: float between 0 and 1. Fraction of the input units to drop.
      data_format: 'channels_first' or 'channels_last'.
          In 'channels_first' mode, the channels dimension
          (the depth) is at index 1,
          in 'channels_last' mode is it at index 3.
          It defaults to the `image_data_format` value found in your
          Keras config file at `~/.keras/keras.json`.
          If you never set it, then it will be "channels_last".

  Input shape:
      4D tensor with shape:
      `(samples, channels, rows, cols)` if data_format='channels_first'
      or 4D tensor with shape:
      `(samples, rows, cols, channels)` if data_format='channels_last'.

  Output shape:
      Same as input

  References:
      - [Efficient Object Localization Using Convolutional
        Networks](https://arxiv.org/abs/1411.4280)
  """

  def __init__(self, rate, data_format=None, **kwargs):
    super(SpatialDropout2D, self).__init__(rate, **kwargs)
    if data_format is None:
      data_format = K.image_data_format()
    if data_format not in {'channels_last', 'channels_first'}:
      raise ValueError('data_format must be in '
                       '{"channels_last", "channels_first"}')
    self.data_format = data_format
    self.input_spec = InputSpec(ndim=4)

  def _get_noise_shape(self, inputs):
    input_shape = array_ops.shape(inputs)
    if self.data_format == 'channels_first':
      return (input_shape[0], input_shape[1], 1, 1)
    elif self.data_format == 'channels_last':
      return (input_shape[0], 1, 1, input_shape[3])


@tf_export('keras.layers.SpatialDropout3D')
class SpatialDropout3D(Dropout):
  """Spatial 3D version of Dropout.

  This version performs the same function as Dropout, however it drops
  entire 3D feature maps instead of individual elements. If adjacent voxels
  within feature maps are strongly correlated (as is normally the case in
  early convolution layers) then regular dropout will not regularize the
  activations and will otherwise just result in an effective learning rate
  decrease. In this case, SpatialDropout3D will help promote independence
  between feature maps and should be used instead.

  Arguments:
      rate: float between 0 and 1. Fraction of the input units to drop.
      data_format: 'channels_first' or 'channels_last'.
          In 'channels_first' mode, the channels dimension (the depth)
          is at index 1, in 'channels_last' mode is it at index 4.
          It defaults to the `image_data_format` value found in your
          Keras config file at `~/.keras/keras.json`.
          If you never set it, then it will be "channels_last".

  Input shape:
      5D tensor with shape:
      `(samples, channels, dim1, dim2, dim3)` if data_format='channels_first'
      or 5D tensor with shape:
      `(samples, dim1, dim2, dim3, channels)` if data_format='channels_last'.

  Output shape:
      Same as input

  References:
      - [Efficient Object Localization Using Convolutional
        Networks](https://arxiv.org/abs/1411.4280)
  """

  def __init__(self, rate, data_format=None, **kwargs):
    super(SpatialDropout3D, self).__init__(rate, **kwargs)
    if data_format is None:
      data_format = K.image_data_format()
    if data_format not in {'channels_last', 'channels_first'}:
      raise ValueError('data_format must be in '
                       '{"channels_last", "channels_first"}')
    self.data_format = data_format
    self.input_spec = InputSpec(ndim=5)

  def _get_noise_shape(self, inputs):
    input_shape = array_ops.shape(inputs)
    if self.data_format == 'channels_first':
      return (input_shape[0], input_shape[1], 1, 1, 1)
    elif self.data_format == 'channels_last':
      return (input_shape[0], 1, 1, 1, input_shape[4])


@tf_export('keras.layers.Activation')
class Activation(Layer):
  """Applies an activation function to an output.

  Arguments:
      activation: name of activation function to use
          or alternatively, a Theano or TensorFlow operation.

  Input shape:
      Arbitrary. Use the keyword argument `input_shape`
      (tuple of integers, does not include the samples axis)
      when using this layer as the first layer in a model.

  Output shape:
      Same shape as input.
  """

  def __init__(self, activation, **kwargs):
    super(Activation, self).__init__(**kwargs)
    self.supports_masking = True
    self.activation = activations.get(activation)

  def call(self, inputs):
    return self.activation(inputs)

  def compute_output_shape(self, input_shape):
    return input_shape

  def get_config(self):
    config = {'activation': activations.serialize(self.activation)}
    base_config = super(Activation, self).get_config()
    return dict(list(base_config.items()) + list(config.items()))


@tf_export('keras.layers.Reshape')
class Reshape(Layer):
  """Reshapes an output to a certain shape.

  Arguments:
      target_shape: target shape. Tuple of integers,
          does not include the samples dimension (batch size).

  Input shape:
      Arbitrary, although all dimensions in the input shaped must be fixed.
      Use the keyword argument `input_shape`
      (tuple of integers, does not include the samples axis)
      when using this layer as the first layer in a model.

  Output shape:
      `(batch_size,) + target_shape`

  Example:

  ```python
      # as first layer in a Sequential model
      model = Sequential()
      model.add(Reshape((3, 4), input_shape=(12,)))
      # now: model.output_shape == (None, 3, 4)
      # note: `None` is the batch dimension

      # as intermediate layer in a Sequential model
      model.add(Reshape((6, 2)))
      # now: model.output_shape == (None, 6, 2)

      # also supports shape inference using `-1` as dimension
      model.add(Reshape((-1, 2, 2)))
      # now: model.output_shape == (None, 3, 2, 2)
  ```
  """

  def __init__(self, target_shape, **kwargs):
    super(Reshape, self).__init__(**kwargs)
    self.target_shape = tuple(target_shape)

  def _fix_unknown_dimension(self, input_shape, output_shape):
    """Find and replace a missing dimension in an output shape.

    This is a near direct port of the internal Numpy function
    `_fix_unknown_dimension` in `numpy/core/src/multiarray/shape.c`

    Arguments:
        input_shape: shape of array being reshaped
        output_shape: desired shape of the array with at most
            a single -1 which indicates a dimension that should be
            derived from the input shape.

    Returns:
        The new output shape with a -1 replaced with its computed value.

        Raises a ValueError if the total array size of the output_shape is
        different then the input_shape, or more than one unknown dimension
        is specified.

    Raises:
        ValueError: in case of invalid values
            for `input_shape` or `input_shape`.
    """
    output_shape = list(output_shape)
    msg = 'total size of new array must be unchanged'

    known, unknown = 1, None
    for index, dim in enumerate(output_shape):
      if dim < 0:
        if unknown is None:
          unknown = index
        else:
          raise ValueError('Can only specify one unknown dimension.')
      else:
        known *= dim

    original = np.prod(input_shape, dtype=int)
    if unknown is not None:
      if known == 0 or original % known != 0:
        raise ValueError(msg)
      output_shape[unknown] = original // known
    elif original != known:
      raise ValueError(msg)
    return output_shape

  def compute_output_shape(self, input_shape):
    input_shape = tensor_shape.TensorShape(input_shape).as_list()
    if None in input_shape[1:]:
      output_shape = [input_shape[0]]
      # input shape (partially) unknown? replace -1's with None's
      output_shape += tuple(s if s != -1 else None for s in self.target_shape)
    else:
      output_shape = [input_shape[0]]
      output_shape += self._fix_unknown_dimension(input_shape[1:],
                                                  self.target_shape)
    return tensor_shape.TensorShape(output_shape)

  def call(self, inputs):
    return array_ops.reshape(inputs,
                             (array_ops.shape(inputs)[0],) + self.target_shape)

  def get_config(self):
    config = {'target_shape': self.target_shape}
    base_config = super(Reshape, self).get_config()
    return dict(list(base_config.items()) + list(config.items()))


@tf_export('keras.layers.Permute')
class Permute(Layer):
  """Permutes the dimensions of the input according to a given pattern.

  Useful for e.g. connecting RNNs and convnets together.

  Example:

  ```python
      model = Sequential()
      model.add(Permute((2, 1), input_shape=(10, 64)))
      # now: model.output_shape == (None, 64, 10)
      # note: `None` is the batch dimension
  ```

  Arguments:
      dims: Tuple of integers. Permutation pattern, does not include the
          samples dimension. Indexing starts at 1.
          For instance, `(2, 1)` permutes the first and second dimension
          of the input.

  Input shape:
      Arbitrary. Use the keyword argument `input_shape`
      (tuple of integers, does not include the samples axis)
      when using this layer as the first layer in a model.

  Output shape:
      Same as the input shape, but with the dimensions re-ordered according
      to the specified pattern.
  """

  def __init__(self, dims, **kwargs):
    super(Permute, self).__init__(**kwargs)
    self.dims = tuple(dims)
    self.input_spec = InputSpec(ndim=len(self.dims) + 1)

  def compute_output_shape(self, input_shape):
    input_shape = tensor_shape.TensorShape(input_shape).as_list()
    output_shape = copy.copy(input_shape)
    for i, dim in enumerate(self.dims):
      target_dim = input_shape[dim]
      output_shape[i + 1] = target_dim
    return tensor_shape.TensorShape(output_shape)

  def call(self, inputs):
    return array_ops.transpose(inputs, perm=(0,) + self.dims)

  def get_config(self):
    config = {'dims': self.dims}
    base_config = super(Permute, self).get_config()
    return dict(list(base_config.items()) + list(config.items()))


@tf_export('keras.layers.Flatten')
class Flatten(Layer):
  """Flattens the input. Does not affect the batch size.

  Arguments:
      data_format: A string,
          one of `channels_last` (default) or `channels_first`.
          The ordering of the dimensions in the inputs.
          `channels_last` corresponds to inputs with shape
          `(batch, ..., channels)` while `channels_first` corresponds to
          inputs with shape `(batch, channels, ...)`.
          It defaults to the `image_data_format` value found in your
          Keras config file at `~/.keras/keras.json`.
          If you never set it, then it will be "channels_last".

  Example:

  ```python
      model = Sequential()
      model.add(Convolution2D(64, 3, 3,
                              border_mode='same',
                              input_shape=(3, 32, 32)))
      # now: model.output_shape == (None, 64, 32, 32)

      model.add(Flatten())
      # now: model.output_shape == (None, 65536)
  ```
  """

  def __init__(self, data_format=None, **kwargs):
    super(Flatten, self).__init__(**kwargs)
    self.data_format = conv_utils.normalize_data_format(data_format)
    self.input_spec = InputSpec(min_ndim=2)

  def call(self, inputs):
    if self.data_format == 'channels_first':
      permutation = [0]
      permutation.extend([i for i in
                          range(2, K.ndim(inputs))])
      permutation.append(1)
      inputs = array_ops.transpose(inputs, perm=permutation)

    outputs = array_ops.reshape(inputs, (array_ops.shape(inputs)[0], -1))
    if not context.executing_eagerly():
      outputs.set_shape(self.compute_output_shape(inputs.get_shape()))
    return outputs

  def compute_output_shape(self, input_shape):
    input_shape = tensor_shape.TensorShape(input_shape).as_list()
    output_shape = [input_shape[0]]
    if all(input_shape[1:]):
      output_shape += [np.prod(input_shape[1:])]
    else:
      output_shape += [None]
    return tensor_shape.TensorShape(output_shape)

  def get_config(self):
    config = {'data_format': self.data_format}
    base_config = super(Flatten, self).get_config()
    return dict(list(base_config.items()) + list(config.items()))


@tf_export('keras.layers.RepeatVector')
class RepeatVector(Layer):
  """Repeats the input n times.

  Example:

  ```python
      model = Sequential()
      model.add(Dense(32, input_dim=32))
      # now: model.output_shape == (None, 32)
      # note: `None` is the batch dimension

      model.add(RepeatVector(3))
      # now: model.output_shape == (None, 3, 32)
  ```

  Arguments:
      n: integer, repetition factor.

  Input shape:
      2D tensor of shape `(num_samples, features)`.

  Output shape:
      3D tensor of shape `(num_samples, n, features)`.
  """

  def __init__(self, n, **kwargs):
    super(RepeatVector, self).__init__(**kwargs)
    self.n = n
    self.input_spec = InputSpec(ndim=2)

  def compute_output_shape(self, input_shape):
    input_shape = tensor_shape.TensorShape(input_shape).as_list()
    return tensor_shape.TensorShape([input_shape[0], self.n, input_shape[1]])

  def call(self, inputs):
    return K.repeat(inputs, self.n)

  def get_config(self):
    config = {'n': self.n}
    base_config = super(RepeatVector, self).get_config()
    return dict(list(base_config.items()) + list(config.items()))


@tf_export('keras.layers.Lambda')
class Lambda(Layer):
  """Wraps arbitrary expression as a `Layer` object.

  Examples:

  ```python
      # add a x -> x^2 layer
      model.add(Lambda(lambda x: x ** 2))
  ```
  ```python
      # add a layer that returns the concatenation
      # of the positive part of the input and
      # the opposite of the negative part

      def antirectifier(x):
          x -= K.mean(x, axis=1, keepdims=True)
          x = K.l2_normalize(x, axis=1)
          pos = K.relu(x)
          neg = K.relu(-x)
          return K.concatenate([pos, neg], axis=1)

      model.add(Lambda(antirectifier))
  ```

  Arguments:
      function: The function to be evaluated.
          Takes input tensor as first argument.
      output_shape: Expected output shape from function.
            This argument can be inferred if not explicitly provided.
            Can be a tuple or function.
            If a tuple, it only specifies the first dimension onward;
                 sample dimension is assumed either the same as the input:
                 `output_shape = (input_shape[0], ) + output_shape`
                 or, the input is `None` and
                 the sample dimension is also `None`:
                 `output_shape = (None, ) + output_shape`
            If a function, it specifies the entire shape as a function of the
            input shape: `output_shape = f(input_shape)`
      arguments: optional dictionary of keyword arguments to be passed
            to the function.

  Input shape:
      Arbitrary. Use the keyword argument input_shape
      (tuple of integers, does not include the samples axis)
      when using this layer as the first layer in a model.

  Output shape:
      Specified by `output_shape` argument
  """

  def __init__(self, function, output_shape=None, mask=None, arguments=None,
               **kwargs):
    super(Lambda, self).__init__(**kwargs)
    self.function = function
    self.arguments = arguments if arguments else {}
    if mask is not None:
      self.supports_masking = True
    self.mask = mask
    if output_shape is None:
      self._output_shape = None
    elif isinstance(output_shape, (tuple, list)):
      self._output_shape = tuple(output_shape)
    else:
      if not callable(output_shape):
        raise TypeError('In Lambda, `output_shape` '
                        'must be a list, a tuple, or a function.')
      self._output_shape = output_shape

  def compute_output_shape(self, input_shape):
    input_shape = tuple(tensor_shape.TensorShape(input_shape).as_list())

    if self._output_shape is None:
      if context.executing_eagerly():
        raise NotImplementedError
      x = K.placeholder(shape=input_shape)
      x = self.call(x)
      if isinstance(x, list):
        return [tensor_shape.TensorShape(K.int_shape(x_elem)) for x_elem in x]
      else:
        return tensor_shape.TensorShape(K.int_shape(x))
    elif isinstance(self._output_shape, (tuple, list)):
      if isinstance(input_shape, list):
        num_samples = input_shape[0][0]
      else:
        num_samples = input_shape[0] if input_shape else None
      return tensor_shape.TensorShape((num_samples,) +
                                      tuple(self._output_shape))
    else:
      shape = self._output_shape(input_shape)
      if not isinstance(shape, (list, tuple)):
        raise ValueError(
            '`output_shape` function must return a tuple or a list of tuples.')
      if isinstance(shape, list):
        if isinstance(shape[0], int) or shape[0] is None:
          shape = tuple(shape)
      return tensor_shape.TensorShape(shape)

  def call(self, inputs, mask=None):
    arguments = self.arguments
    if generic_utils.has_arg(self.function, 'mask'):
      arguments['mask'] = mask
    return self.function(inputs, **arguments)

  def compute_mask(self, inputs, mask=None):
    if callable(self.mask):
      return self.mask(inputs, mask)
    return self.mask

  def get_config(self):
    module = self.function.__module__
    if isinstance(self.function, python_types.LambdaType):
      function = generic_utils.func_dump(self.function)
      function_type = 'lambda'
    else:
      function = self.function.__name__
      function_type = 'function'

    output_shape_module = None
    if isinstance(self._output_shape, python_types.LambdaType):
      output_shape = generic_utils.func_dump(self._output_shape)
      output_shape_type = 'lambda'
      output_shape_module = self._output_shape.__module__
    elif callable(self._output_shape):
      output_shape = self._output_shape.__name__
      output_shape_type = 'function'
      output_shape_module = self._output_shape.__module__
    else:
      output_shape = self._output_shape
      output_shape_type = 'raw'

    config = {
        'function': function,
        'module': module,
        'function_type': function_type,
        'output_shape': output_shape,
        'output_shape_type': output_shape_type,
        'output_shape_module': output_shape_module,
        'arguments': self.arguments
    }
    base_config = super(Lambda, self).get_config()
    return dict(list(base_config.items()) + list(config.items()))

  @classmethod
  def from_config(cls, config, custom_objects=None):
    config = config.copy()
    globs = globals()
    module = config.pop('module', None)
    if module in sys.modules:
      globs.update(sys.modules[module].__dict__)
    elif module is not None:
      # Note: we don't know the name of the function if it's a lambda.
      warnings.warn('{} is not loaded, but a Lambda layer uses it. '
                    'It may cause errors.'.format(module)
                    , UserWarning)
    if custom_objects:
      globs.update(custom_objects)
    function_type = config.pop('function_type')
    if function_type == 'function':
      # Simple lookup in custom objects
      function = generic_utils.deserialize_keras_object(
          config['function'],
          custom_objects=custom_objects,
          printable_module_name='function in Lambda layer')
    elif function_type == 'lambda':
      # Unsafe deserialization from bytecode
      function = generic_utils.func_load(config['function'], globs=globs)
    else:
      raise TypeError('Unknown function type:', function_type)

    output_shape_module = config.pop('output_shape_module', None)
    if output_shape_module in sys.modules:
      globs.update(sys.modules[output_shape_module].__dict__)
    elif output_shape_module is not None:
      # Note: we don't know the name of the function if it's a lambda.
      warnings.warn('{} is not loaded, but a Lambda layer uses it. '
                    'It may cause errors.'.format(output_shape_module)
                    , UserWarning)
    output_shape_type = config.pop('output_shape_type')
    if output_shape_type == 'function':
      # Simple lookup in custom objects
      output_shape = generic_utils.deserialize_keras_object(
          config['output_shape'],
          custom_objects=custom_objects,
          printable_module_name='output_shape function in Lambda layer')
    elif output_shape_type == 'lambda':
      # Unsafe deserialization from bytecode
      output_shape = generic_utils.func_load(config['output_shape'],
                                             globs=globs)
    else:
      output_shape = config['output_shape']

    # If arguments were numpy array, they have been saved as
    # list. We need to recover the ndarray
    if 'arguments' in config:
      for key in config['arguments']:
        if isinstance(config['arguments'][key], dict):
          arg_dict = config['arguments'][key]
          if 'type' in arg_dict and arg_dict['type'] == 'ndarray':
            # Overwrite the argument with its numpy translation
            config['arguments'][key] = np.array(arg_dict['value'])

    config['function'] = function
    config['output_shape'] = output_shape
    return cls(**config)


@tf_export('keras.layers.Dense')
class Dense(Layer):
  """Just your regular densely-connected NN layer.

  `Dense` implements the operation:
  `output = activation(dot(input, kernel) + bias)`
  where `activation` is the element-wise activation function
  passed as the `activation` argument, `kernel` is a weights matrix
  created by the layer, and `bias` is a bias vector created by the layer
  (only applicable if `use_bias` is `True`).

  Note: if the input to the layer has a rank greater than 2, then
  it is flattened prior to the initial dot product with `kernel`.

  Example:

  ```python
      # as first layer in a sequential model:
      model = Sequential()
      model.add(Dense(32, input_shape=(16,)))
      # now the model will take as input arrays of shape (*, 16)
      # and output arrays of shape (*, 32)

      # after the first layer, you don't need to specify
      # the size of the input anymore:
      model.add(Dense(32))
  ```

  Arguments:
      units: Positive integer, dimensionality of the output space.
      activation: Activation function to use.
          If you don't specify anything, no activation is applied
          (ie. "linear" activation: `a(x) = x`).
      use_bias: Boolean, whether the layer uses a bias vector.
      kernel_initializer: Initializer for the `kernel` weights matrix.
      bias_initializer: Initializer for the bias vector.
      kernel_regularizer: Regularizer function applied to
          the `kernel` weights matrix.
      bias_regularizer: Regularizer function applied to the bias vector.
      activity_regularizer: Regularizer function applied to
          the output of the layer (its "activation")..
      kernel_constraint: Constraint function applied to
          the `kernel` weights matrix.
      bias_constraint: Constraint function applied to the bias vector.

  Input shape:
      nD tensor with shape: `(batch_size, ..., input_dim)`.
      The most common situation would be
      a 2D input with shape `(batch_size, input_dim)`.

  Output shape:
      nD tensor with shape: `(batch_size, ..., units)`.
      For instance, for a 2D input with shape `(batch_size, input_dim)`,
      the output would have shape `(batch_size, units)`.
  """

  def __init__(self,
               units,
               activation=None,
               use_bias=True,
               kernel_initializer='glorot_uniform',
               bias_initializer='zeros',
               kernel_regularizer=None,
               bias_regularizer=None,
               activity_regularizer=None,
               kernel_constraint=None,
               bias_constraint=None,
               **kwargs):
    if 'input_shape' not in kwargs and 'input_dim' in kwargs:
      kwargs['input_shape'] = (kwargs.pop('input_dim'),)

    super(Dense, self).__init__(
        activity_regularizer=regularizers.get(activity_regularizer), **kwargs)
    self.units = int(units)
    self.activation = activations.get(activation)
    self.use_bias = use_bias
    self.kernel_initializer = initializers.get(kernel_initializer)
    self.bias_initializer = initializers.get(bias_initializer)
    self.kernel_regularizer = regularizers.get(kernel_regularizer)
    self.bias_regularizer = regularizers.get(bias_regularizer)
    self.kernel_constraint = constraints.get(kernel_constraint)
    self.bias_constraint = constraints.get(bias_constraint)

    self.supports_masking = True
    self.input_spec = InputSpec(min_ndim=2)

  def build(self, input_shape):
    input_shape = tensor_shape.TensorShape(input_shape)
    if input_shape[-1].value is None:
      raise ValueError('The last dimension of the inputs to `Dense` '
                       'should be defined. Found `None`.')
    self.input_spec = InputSpec(min_ndim=2,
                                axes={-1: input_shape[-1].value})
    self.kernel = self.add_weight(
        'kernel',
        shape=[input_shape[-1].value, self.units],
        initializer=self.kernel_initializer,
        regularizer=self.kernel_regularizer,
        constraint=self.kernel_constraint,
        dtype=self.dtype,
        trainable=True)
    if self.use_bias:
      self.bias = self.add_weight(
          'bias',
          shape=[self.units,],
          initializer=self.bias_initializer,
          regularizer=self.bias_regularizer,
          constraint=self.bias_constraint,
          dtype=self.dtype,
          trainable=True)
    else:
      self.bias = None
    self.built = True

  def call(self, inputs):
    inputs = ops.convert_to_tensor(inputs, dtype=self.dtype)
    shape = inputs.get_shape().as_list()
    if len(shape) > 2:
      # Broadcasting is required for the inputs.
      outputs = standard_ops.tensordot(inputs, self.kernel, [[len(shape) - 1],
                                                             [0]])
      # Reshape the output back to the original ndim of the input.
      if not context.executing_eagerly():
        output_shape = shape[:-1] + [self.units]
        outputs.set_shape(output_shape)
    else:
      outputs = gen_math_ops.mat_mul(inputs, self.kernel)
    if self.use_bias:
      outputs = nn.bias_add(outputs, self.bias)
    if self.activation is not None:
      return self.activation(outputs)  # pylint: disable=not-callable
    return outputs

  def compute_output_shape(self, input_shape):
    input_shape = tensor_shape.TensorShape(input_shape)
    input_shape = input_shape.with_rank_at_least(2)
    if input_shape[-1].value is None:
      raise ValueError(
          'The innermost dimension of input_shape must be defined, but saw: %s'
          % input_shape)
    return input_shape[:-1].concatenate(self.units)

  def get_config(self):
    config = {
        'units': self.units,
        'activation': activations.serialize(self.activation),
        'use_bias': self.use_bias,
        'kernel_initializer': initializers.serialize(self.kernel_initializer),
        'bias_initializer': initializers.serialize(self.bias_initializer),
        'kernel_regularizer': regularizers.serialize(self.kernel_regularizer),
        'bias_regularizer': regularizers.serialize(self.bias_regularizer),
        'activity_regularizer':
            regularizers.serialize(self.activity_regularizer),
        'kernel_constraint': constraints.serialize(self.kernel_constraint),
        'bias_constraint': constraints.serialize(self.bias_constraint)
    }
    base_config = super(Dense, self).get_config()
    return dict(list(base_config.items()) + list(config.items()))


@tf_export('keras.layers.ActivityRegularization')
class ActivityRegularization(Layer):
  """Layer that applies an update to the cost function based input activity.

  Arguments:
      l1: L1 regularization factor (positive float).
      l2: L2 regularization factor (positive float).

  Input shape:
      Arbitrary. Use the keyword argument `input_shape`
      (tuple of integers, does not include the samples axis)
      when using this layer as the first layer in a model.

  Output shape:
      Same shape as input.
  """

  def __init__(self, l1=0., l2=0., **kwargs):
    super(ActivityRegularization, self).__init__(
        activity_regularizer=regularizers.L1L2(l1=l1, l2=l2), **kwargs)
    self.supports_masking = True
    self.l1 = l1
    self.l2 = l2

  def compute_output_shape(self, input_shape):
    return input_shape

  def get_config(self):
    config = {'l1': self.l1, 'l2': self.l2}
    base_config = super(ActivityRegularization, self).get_config()
    return dict(list(base_config.items()) + list(config.items()))