path: root/tensorflow/python/ops/nn_ops.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.
# ==============================================================================
"""Wrappers for primitive Neural Net (NN) Operations."""

# pylint: disable=invalid-name
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import numbers

import numpy as np

from tensorflow.python.framework import common_shapes
from tensorflow.python.framework import dtypes
from tensorflow.python.framework import graph_util
from tensorflow.python.framework import ops
from tensorflow.python.framework import tensor_shape
from tensorflow.python.framework import tensor_util
from tensorflow.python.ops import array_ops
from tensorflow.python.ops import gen_nn_ops
from tensorflow.python.ops import math_ops
from tensorflow.python.ops import random_ops
# go/tf-wildcard-import
# pylint: disable=wildcard-import
from tensorflow.python.ops.gen_nn_ops import *
# pylint: enable=wildcard-import

# Aliases for some automatically-generated names.
local_response_normalization = gen_nn_ops.lrn


def atrous_conv2d(value, filters, rate, padding, name=None):
  """Atrous convolution (a.k.a. convolution with holes or dilated convolution).

  Computes a 2-D atrous convolution, also known as convolution with holes or
  dilated convolution, given 4-D `value` and `filters` tensors. If the `rate`
  parameter is equal to one, it performs regular 2-D convolution. If the `rate`
  parameter is greater than one, it performs convolution with holes, sampling
  the input values every `rate` pixels in the `height` and `width` dimensions.
  This is equivalent to convolving the input with a set of upsampled filters,
  produced by inserting `rate - 1` zeros between two consecutive values of the
  filters along the `height` and `width` dimensions, hence the name atrous
  convolution or convolution with holes (the French word trous means holes in
  English).

  More specifically:

      output[b, i, j, k] = sum_{di, dj, q} filters[di, dj, q, k] *
            value[b, i + rate * di, j + rate * dj, q]

  Atrous convolution allows us to explicitly control how densely to compute
  feature responses in fully convolutional networks. Used in conjunction with
  bilinear interpolation, it offers an alternative to `conv2d_transpose` in
  dense prediction tasks such as semantic image segmentation, optical flow
  computation, or depth estimation. It also allows us to effectively enlarge
  the field of view of filters without increasing the number of parameters or
  the amount of computation.

  For a description of atrous convolution and how it can be used for dense
  feature extraction, please see: [Semantic Image Segmentation with Deep
  Convolutional Nets and Fully Connected CRFs](http://arxiv.org/abs/1412.7062).
  The same operation is investigated further in [Multi-Scale Context Aggregation
  by Dilated Convolutions](http://arxiv.org/abs/1511.07122). Previous works
  that effectively use atrous convolution in different ways are, among others,
  [OverFeat: Integrated Recognition, Localization and Detection using
  Convolutional Networks](http://arxiv.org/abs/1312.6229) and [Fast Image
  Scanning with Deep Max-Pooling Convolutional Neural Networks]
  (http://arxiv.org/abs/1302.1700). Atrous convolution is also closely related
  to the so-called noble identities in multi-rate signal processing.

  There are many different ways to implement atrous convolution (see the refs
  above). The implementation here reduces

      atrous_conv2d(value, filters, rate, padding=padding)

  to the following three operations:

      paddings = ...
      net = space_to_batch(value, paddings, block_size=rate)
      net = conv2d(net, filters, strides=[1, 1, 1, 1], padding="VALID")
      crops = ...
      net = batch_to_space(net, crops, block_size=rate)

  Advanced usage. Note the following optimization: A sequence of `atrous_conv2d`
  operations with identical `rate` parameters, 'SAME' `padding`, and filters
  with odd heights/ widths:

      net = atrous_conv2d(net, filters1, rate, padding="SAME")
      net = atrous_conv2d(net, filters2, rate, padding="SAME")
      ...
      net = atrous_conv2d(net, filtersK, rate, padding="SAME")

  can be equivalently performed cheaper in terms of computation and memory as:

      pad = ...  # padding so that the input dims are multiples of rate
      net = space_to_batch(net, paddings=pad, block_size=rate)
      net = conv2d(net, filters1, strides=[1, 1, 1, 1], padding="SAME")
      net = conv2d(net, filters2, strides=[1, 1, 1, 1], padding="SAME")
      ...
      net = conv2d(net, filtersK, strides=[1, 1, 1, 1], padding="SAME")
      net = batch_to_space(net, crops=pad, block_size=rate)

  because a pair of consecutive `space_to_batch` and `batch_to_space` ops with
  the same `block_size` cancel out when their respective `paddings` and `crops`
  inputs are identical.

  Args:
    value: A 4-D `Tensor` of type `float`. It needs to be in the default "NHWC"
      format. Its shape is `[batch, in_height, in_width, in_channels]`.
    filters: A 4-D `Tensor` with the same type as `value` and shape
      `[filter_height, filter_width, in_channels, out_channels]`. `filters`'
      `in_channels` dimension must match that of `value`. Atrous convolution is
      equivalent to standard convolution with upsampled filters with effective
      height `filter_height + (filter_height - 1) * (rate - 1)` and effective
      width `filter_width + (filter_width - 1) * (rate - 1)`, produced by
      inserting `rate - 1` zeros along consecutive elements across the
      `filters`' spatial dimensions.
    rate: A positive int32. The stride with which we sample input values across
      the `height` and `width` dimensions. Equivalently, the rate by which we
      upsample the filter values by inserting zeros across the `height` and
      `width` dimensions. In the literature, the same parameter is sometimes
      called `input stride` or `dilation`.
    padding: A string, either `'VALID'` or `'SAME'`. The padding algorithm.
    name: Optional name for the returned tensor.

  Returns:
    A `Tensor` with the same type as `value`.

  Raises:
    ValueError: If input/output depth does not match `filters`' shape, or if
      padding is other than `'VALID'` or `'SAME'`.
  """
  with ops.name_scope(name, "atrous_conv2d", [value, filters]) as name:
    value = ops.convert_to_tensor(value, name="value")
    filters = ops.convert_to_tensor(filters, name="filters")
    if not value.get_shape()[3].is_compatible_with(filters.get_shape()[2]):
      raise ValueError(
          "value's input channels does not match filters' input channels, "
          "{} != {}".format(value.get_shape()[3], filters.get_shape()[2]))
    if rate < 1:
      raise ValueError("rate {} cannot be less than one".format(rate))

    if rate == 1:
      value = gen_nn_ops.conv2d(input=value,
                                filter=filters,
                                strides=[1, 1, 1, 1],
                                padding=padding)
      return value

    # We have two padding contributions. The first is used for converting "SAME"
    # to "VALID". The second is required so that the height and width of the
    # zero-padded value tensor are multiples of rate.

    # Padding required to reduce to "VALID" convolution
    if padding == "SAME":
      # Handle filters whose shape is unknown during graph creation.
      if filters.get_shape().is_fully_defined():
        filter_shape = filters.get_shape().as_list()
      else:
        filter_shape = array_ops.shape(filters)
      filter_height, filter_width = filter_shape[0], filter_shape[1]

      # Spatial dimensions of the filters and the upsampled filters in which we
      # introduce (rate - 1) zeros between consecutive filter values.
      filter_height_up = filter_height + (filter_height - 1) * (rate - 1)
      filter_width_up = filter_width + (filter_width - 1) * (rate - 1)

      pad_height = filter_height_up - 1
      pad_width = filter_width_up - 1

      # When pad_height (pad_width) is odd, we pad more to bottom (right),
      # following the same convention as conv2d().
      pad_top = pad_height // 2
      pad_bottom = pad_height - pad_top
      pad_left = pad_width // 2
      pad_right = pad_width - pad_left
    elif padding == "VALID":
      pad_top = 0
      pad_bottom = 0
      pad_left = 0
      pad_right = 0
    else:
      raise ValueError("Invalid padding")

    # Handle input whose shape is unknown during graph creation.
    if value.get_shape().is_fully_defined():
      value_shape = value.get_shape().as_list()
    else:
      value_shape = array_ops.shape(value)

    in_height = value_shape[1] + pad_top + pad_bottom
    in_width = value_shape[2] + pad_left + pad_right

    # More padding so that rate divides the height and width of the input.
    pad_bottom_extra = (rate - in_height % rate) % rate
    pad_right_extra = (rate - in_width % rate) % rate

    # The paddings argument to space_to_batch includes both padding components.
    space_to_batch_pad = [[pad_top, pad_bottom + pad_bottom_extra],
                          [pad_left, pad_right + pad_right_extra]]

    value = array_ops.space_to_batch(input=value,
                                     paddings=space_to_batch_pad,
                                     block_size=rate)

    value = gen_nn_ops.conv2d(input=value,
                              filter=filters,
                              strides=[1, 1, 1, 1],
                              padding="VALID",
                              name=name)

    # The crops argument to batch_to_space is just the extra padding component.
    batch_to_space_crop = [[0, pad_bottom_extra], [0, pad_right_extra]]

    value = array_ops.batch_to_space(input=value,
                                     crops=batch_to_space_crop,
                                     block_size=rate)

    return value


def conv2d_transpose(value,
                     filter,
                     output_shape,
                     strides,
                     padding="SAME",
                     name=None):
  """The transpose of `conv2d`.

  This operation is sometimes called "deconvolution" after [Deconvolutional
  Networks](http://www.matthewzeiler.com/pubs/cvpr2010/cvpr2010.pdf), but is
  actually the transpose (gradient) of `conv2d` rather than an actual
  deconvolution.

  Args:
    value: A 4-D `Tensor` of type `float` and shape
      `[batch, height, width, in_channels]`.
    filter: A 4-D `Tensor` with the same type as `value` and shape
      `[height, width, output_channels, in_channels]`.  `filter`'s
      `in_channels` dimension must match that of `value`.
    output_shape: A 1-D `Tensor` representing the output shape of the
      deconvolution op.
    strides: A list of ints. The stride of the sliding window for each
      dimension of the input tensor.
    padding: A string, either `'VALID'` or `'SAME'`. The padding algorithm.
      See the [comment here](https://www.tensorflow.org/api_docs/python/nn.html#convolution)
    name: Optional name for the returned tensor.

  Returns:
    A `Tensor` with the same type as `value`.

  Raises:
    ValueError: If input/output depth does not match `filter`'s shape, or if
      padding is other than `'VALID'` or `'SAME'`.
  """
  with ops.name_scope(name, "conv2d_transpose",
                      [value, filter, output_shape]) as name:
    value = ops.convert_to_tensor(value, name="value")
    filter = ops.convert_to_tensor(filter, name="filter")
    if not value.get_shape()[3].is_compatible_with(filter.get_shape()[3]):
      raise ValueError("input channels does not match filter's input channels, "
                       "{} != {}".format(value.get_shape()[3], filter.get_shape(
                       )[3]))

    output_shape_ = ops.convert_to_tensor(output_shape, name="output_shape")
    if not output_shape_.get_shape().is_compatible_with(tensor_shape.vector(4)):
      raise ValueError("output_shape must have shape (4,), got {}"
                       .format(output_shape_.get_shape()))

    if isinstance(output_shape, (list, np.ndarray)):
      # output_shape's shape should be == [4] if reached this point.
      if not filter.get_shape()[2].is_compatible_with(output_shape[3]):
        raise ValueError(
            "output_shape does not match filter's output channels, "
            "{} != {}".format(output_shape[3], filter.get_shape()[2]))

    if padding != "VALID" and padding != "SAME":
      raise ValueError("padding must be either VALID or SAME:"
                       " {}".format(padding))

    return gen_nn_ops.conv2d_backprop_input(input_sizes=output_shape_,
                                            filter=filter,
                                            out_backprop=value,
                                            strides=strides,
                                            padding=padding,
                                            name=name)


def conv3d_transpose(value,
                     filter,
                     output_shape,
                     strides,
                     padding="SAME",
                     name=None):
  """The transpose of `conv3d`.

  This operation is sometimes called "deconvolution" after [Deconvolutional
  Networks](http://www.matthewzeiler.com/pubs/cvpr2010/cvpr2010.pdf), but is
  actually the transpose (gradient) of `conv3d` rather than an actual
  deconvolution.

  Args:
    value: A 5-D `Tensor` of type `float` and shape
      `[batch, depth, height, width, in_channels]`.
    filter: A 5-D `Tensor` with the same type as `value` and shape
      `[depth, height, width, output_channels, in_channels]`.  `filter`'s
      `in_channels` dimension must match that of `value`.
    output_shape: A 1-D `Tensor` representing the output shape of the
      deconvolution op.
    strides: A list of ints. The stride of the sliding window for each
      dimension of the input tensor.
    padding: A string, either `'VALID'` or `'SAME'`. The padding algorithm.
      See the [comment here](https://www.tensorflow.org/api_docs/python/nn.html#convolution)
    name: Optional name for the returned tensor.

  Returns:
    A `Tensor` with the same type as `value`.

  Raises:
    ValueError: If input/output depth does not match `filter`'s shape, or if
      padding is other than `'VALID'` or `'SAME'`.
  """
  with ops.name_scope(name, "conv3d_transpose",
                      [value, filter, output_shape]) as name:
    value = ops.convert_to_tensor(value, name="value")
    filter = ops.convert_to_tensor(filter, name="filter")
    if not value.get_shape()[4].is_compatible_with(filter.get_shape()[4]):
      raise ValueError("input channels does not match filter's input channels, "
                       "{} != {}".format(value.get_shape()[4], filter.get_shape(
                       )[4]))

    output_shape_ = ops.convert_to_tensor(output_shape, name="output_shape")
    if not output_shape_.get_shape().is_compatible_with(tensor_shape.vector(5)):
      raise ValueError("output_shape must have shape (5,), got {}"
                       .format(output_shape_.get_shape()))

    if isinstance(output_shape, (list, np.ndarray)):
      # output_shape's shape should be == [5] if reached this point.
      if not filter.get_shape()[3].is_compatible_with(output_shape[4]):
        raise ValueError(
            "output_shape does not match filter's output channels, "
            "{} != {}".format(output_shape[4], filter.get_shape()[3]))

    if padding != "VALID" and padding != "SAME":
      raise ValueError("padding must be either VALID or SAME:"
                       " {}".format(padding))

    return gen_nn_ops.conv3d_backprop_input_v2(input_sizes=output_shape_,
                                               filter=filter,
                                               out_backprop=value,
                                               strides=strides,
                                               padding=padding,
                                               name=name)


# pylint: disable=protected-access
def bias_add(value, bias, data_format=None, name=None):
  """Adds `bias` to `value`.

  This is (mostly) a special case of `tf.add` where `bias` is restricted to 1-D.
  Broadcasting is supported, so `value` may have any number of dimensions.
  Unlike `tf.add`, the type of `bias` is allowed to differ from `value` in the
  case where both types are quantized.

  Args:
    value: A `Tensor` with type `float`, `double`, `int64`, `int32`, `uint8`,
      `int16`, `int8`, `complex64`, or `complex128`.
    bias: A 1-D `Tensor` with size matching the last dimension of `value`.
      Must be the same type as `value` unless `value` is a quantized type,
      in which case a different quantized type may be used.
    data_format: A string. 'NHWC' and 'NCHW' are supported.
    name: A name for the operation (optional).

  Returns:
    A `Tensor` with the same type as `value`.
  """
  with ops.name_scope(name, "BiasAdd", [value, bias]) as name:
    value = ops.convert_to_tensor(value, name="input")
    bias = ops.convert_to_tensor(bias, dtype=value.dtype, name="bias")
    return gen_nn_ops._bias_add(value, bias, data_format=data_format, name=name)


ops.RegisterShape("BiasAddV1")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("BiasAdd")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("BiasAddGradV1")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("BiasAddGrad")(common_shapes.call_cpp_shape_fn)


# pylint: disable=protected-access
def bias_add_v1(value, bias, name=None):
  """Adds `bias` to `value`.

  This is a deprecated version of bias_add and will soon to be removed.

  This is (mostly) a special case of `tf.add` where `bias` is restricted to 1-D.
  Broadcasting is supported, so `value` may have any number of dimensions.
  Unlike `tf.add`, the type of `bias` is allowed to differ from `value` in the
  case where both types are quantized.

  Args:
    value: A `Tensor` with type `float`, `double`, `int64`, `int32`, `uint8`,
      `int16`, `int8`, `complex64`, or `complex128`.
    bias: A 1-D `Tensor` with size matching the last dimension of `value`.
      Must be the same type as `value` unless `value` is a quantized type,
      in which case a different quantized type may be used.
    name: A name for the operation (optional).

  Returns:
    A `Tensor` with the same type as `value`.
  """
  with ops.name_scope(name, "BiasAddV1", [value, bias]) as name:
    value = ops.convert_to_tensor(value, name="input")
    bias = ops.convert_to_tensor(bias, dtype=value.dtype, name="bias")
    return gen_nn_ops._bias_add_v1(value, bias, name=name)


def crelu(features, name=None):
  """Computes Concatenated ReLU.

  Concatenates a ReLU which selects only the positive part of the activation
  with a ReLU which selects only the *negative* part of the activation.
  Note that as a result this non-linearity doubles the depth of the activations.
  Source: https://arxiv.org/abs/1603.05201

  Args:
    features: A `Tensor` with type `float`, `double`, `int32`, `int64`, `uint8`,
      `int16`, or `int8`.
    name: A name for the operation (optional).

  Returns:
    A `Tensor` with the same type as `features`.
  """
  with ops.name_scope(name, "CRelu", [features]) as name:
    features = ops.convert_to_tensor(features, name="features")
    return gen_nn_ops.relu(array_ops.concat(array_ops.rank(features) - 1,
                                            [features, -features], name=name))


def relu6(features, name=None):
  """Computes Rectified Linear 6: `min(max(features, 0), 6)`.

  Args:
    features: A `Tensor` with type `float`, `double`, `int32`, `int64`, `uint8`,
      `int16`, or `int8`.
    name: A name for the operation (optional).

  Returns:
    A `Tensor` with the same type as `features`.
  """
  with ops.name_scope(name, "Relu6", [features]) as name:
    features = ops.convert_to_tensor(features, name="features")
    return gen_nn_ops._relu6(features, name=name)


def _flatten_outer_dims(logits):
  """Flattens logits' outer dimensions and keep its last dimension."""
  rank = array_ops.rank(logits)
  last_dim_size = array_ops.slice(
      array_ops.shape(logits), [math_ops.sub(rank, 1)], [1])
  output = array_ops.reshape(logits, array_ops.concat(0, [[-1], last_dim_size]))

  # Set output shape if known.
  shape = logits.get_shape()
  if shape is not None and shape.dims is not None:
    shape = shape.as_list()
    product = 1
    product_valid = True
    for d in shape[:-1]:
      if d is None:
        product_valid = False
        break
      else:
        product *= d
    if product_valid:
      output_shape = [product, shape[-1]]
      output.set_shape(output_shape)

  return output


def _softmax(logits, compute_op, dim=-1, name=None):
  """Helper function for softmax and log_softmax.

  It reshapes and transposes the input logits into a 2-D Tensor and then invokes
  the tf.nn._softmax or tf.nn._log_softmax function. The output would be
  transposed and reshaped back.

  Args:
    logits: A non-empty `Tensor`. Must be one of the following types: `half`,
      `float32`, `float64`.
    compute_op: Either gen_nn_ops._softmax or gen_nn_ops._log_softmax
    dim: The dimension softmax would be performed on. The default is -1 which
      indicates the last dimension.
    name: A name for the operation (optional).

  Returns:
    A `Tensor`. Has the same type as `logits`. Same shape as `logits`.
  Raises:
    InvalidArgumentError: if `logits` is empty or `dim` is beyond the last
      dimension of `logits`.
  """
  def _swap_axis(logits, dim_index, last_index):
    """Swaps logits's dim_index and last_index."""
    return array_ops.transpose(logits, array_ops.concat(
        0, [math_ops.range(dim_index), [last_index],
            math_ops.range(dim_index + 1, last_index), [dim_index]]))

  logits = ops.convert_to_tensor(logits)
  if logits.get_shape().ndims is 2 and dim is -1:
    return compute_op(logits, name=name)

  # We need its original shape for shape inference.
  shape = logits.get_shape()

  # If dim is the last dimension, simply reshape the logits to a matrix and
  # apply the internal softmax.
  if dim is -1:
    input_shape = array_ops.shape(logits)
    logits = _flatten_outer_dims(logits)
    output = compute_op(logits, name=name)
    output = array_ops.reshape(output, input_shape)
    return output

  # If dim is not the last dimension, we have to do a reshape and transpose so
  # that we can still perform softmax on its last dimension.

  # Swap logits' dimension of dim and its last dimension.
  input_rank = array_ops.rank(logits)
  logits = _swap_axis(logits, dim, math_ops.sub(input_rank, 1))
  shape_after_swap = array_ops.shape(logits)

  # Reshape logits into a matrix.
  logits = _flatten_outer_dims(logits)

  # Do the actual softmax on its last dimension.
  output = compute_op(logits, name=name)

  # Transform back the output tensor.
  output = array_ops.reshape(output, shape_after_swap)
  output = _swap_axis(output, dim, math_ops.sub(input_rank, 1))

  # Make shape inference work since reshape and transpose may erase its static
  # shape.
  output.set_shape(shape)

  return output


def softmax(logits, dim=-1, name=None):
  """Computes log softmax activations.

  For each batch `i` and class `j` we have

      softmax = exp(logits) / reduce_sum(exp(logits), dim)

  Args:
    logits: A non-empty `Tensor`. Must be one of the following types: `half`,
      `float32`, `float64`.
    dim: The dimension softmax would be performed on. The default is -1 which
      indicates the last dimension.
    name: A name for the operation (optional).

  Returns:
    A `Tensor`. Has the same type as `logits`. Same shape as `logits`.
  Raises:
    InvalidArgumentError: if `logits` is empty or `dim` is beyond the last
      dimension of `logits`.
  """
  return _softmax(logits, gen_nn_ops._softmax, dim, name)


def log_softmax(logits, dim=-1, name=None):
  """Computes log softmax activations.

  For each batch `i` and class `j` we have

      logsoftmax = logits - reduce_sum(exp(logits), dim)

  Args:
    logits: A non-empty `Tensor`. Must be one of the following types: `half`,
      `float32`, `float64`.
    dim: The dimension softmax would be performed on. The default is -1 which
      indicates the last dimension.
    name: A name for the operation (optional).

  Returns:
    A `Tensor`. Has the same type as `logits`. Same shape as `logits`.

  Raises:
    InvalidArgumentError: if `logits` is empty or `dim` is beyond the last
      dimension of `logits`.
  """
  return _softmax(logits, gen_nn_ops._log_softmax, dim, name)


def softmax_cross_entropy_with_logits(logits, labels, dim=-1, name=None):
  """Computes softmax cross entropy between `logits` and `labels`.

  Measures the probability error in discrete classification tasks in which the
  classes are mutually exclusive (each entry is in exactly one class).  For
  example, each CIFAR-10 image is labeled with one and only one label: an image
  can be a dog or a truck, but not both.

  **NOTE:**  While the classes are mutually exclusive, their probabilities
  need not be.  All that is required is that each row of `labels` is
  a valid probability distribution.  If they are not, the computation of the
  gradient will be incorrect.

  If using exclusive `labels` (wherein one and only
  one class is true at a time), see `sparse_softmax_cross_entropy_with_logits`.

  **WARNING:** This op expects unscaled logits, since it performs a `softmax`
  on `logits` internally for efficiency.  Do not call this op with the
  output of `softmax`, as it will produce incorrect results.

  `logits` and `labels` must have the same shape `[batch_size, num_classes]`
  and the same dtype (either `float16`, `float32`, or `float64`).

  Args:
    logits: Unscaled log probabilities.
    labels: Each row `labels[i]` must be a valid probability distribution.
    dim: The class dimension. Defaulted to -1 which is the last dimension.
    name: A name for the operation (optional).

  Returns:
    A 1-D `Tensor` of length `batch_size` of the same type as `logits` with the
    softmax cross entropy loss.
  """
  # TODO(pcmurray) Raise an error when the labels do not sum to 1. Note: This
  # could break users who call this with bad labels, but disregard the bad
  # results.

  logits = ops.convert_to_tensor(logits)
  labels = ops.convert_to_tensor(labels)
  precise_logits = math_ops.cast(logits, dtypes.float32) if (
      logits.dtype == dtypes.float16) else logits
  input_rank = array_ops.rank(precise_logits)
  # For shape inference.
  shape = logits.get_shape()

  # Move the dim to the end if dim is not the last dimension.
  if dim is not -1:
    def _move_dim_to_end(tensor, dim_index, rank):
      return array_ops.transpose(tensor, array_ops.concat(
          0, [math_ops.range(dim_index), math_ops.range(dim_index + 1, rank),
              [dim_index]]))

    precise_logits = _move_dim_to_end(precise_logits, dim, input_rank)
    labels = _move_dim_to_end(labels, dim, input_rank)

  input_shape = array_ops.shape(precise_logits)

  # Make precise_logits and labels into matrices.
  precise_logits = _flatten_outer_dims(precise_logits)
  labels = _flatten_outer_dims(labels)

  # Do the actual op computation.
  # The second output tensor contains the gradients.  We use it in
  # _CrossEntropyGrad() in nn_grad but not here.
  cost, unused_backprop = gen_nn_ops._softmax_cross_entropy_with_logits(
      precise_logits, labels, name=name)

  # The output cost shape should be the input minus dim.
  output_shape = array_ops.slice(input_shape, [0],
                                 [math_ops.sub(input_rank, 1)])
  cost = array_ops.reshape(cost, output_shape)

  # Make shape inference work since reshape and transpose may erase its static
  # shape.
  if shape is not None and shape.dims is not None:
    shape = shape.as_list()
    del shape[dim]
    cost.set_shape(shape)

  if logits.dtype == dtypes.float16:
    return math_ops.cast(cost, dtypes.float16)
  else:
    return cost


def sparse_softmax_cross_entropy_with_logits(logits, labels, name=None):
  """Computes sparse softmax cross entropy between `logits` and `labels`.

  Measures the probability error in discrete classification tasks in which the
  classes are mutually exclusive (each entry is in exactly one class).  For
  example, each CIFAR-10 image is labeled with one and only one label: an image
  can be a dog or a truck, but not both.

  **NOTE:**  For this operation, the probability of a given label is considered
  exclusive.  That is, soft classes are not allowed, and the `labels` vector
  must provide a single specific index for the true class for each row of
  `logits` (each minibatch entry).  For soft softmax classification with
  a probability distribution for each entry, see
  `softmax_cross_entropy_with_logits`.

  **WARNING:** This op expects unscaled logits, since it performs a softmax
  on `logits` internally for efficiency.  Do not call this op with the
  output of `softmax`, as it will produce incorrect results.

  A common use case is to have logits of shape `[batch_size, num_classes]` and
  labels of shape `[batch_size]`. But higher dimensions are supported.

  Args:
    logits: Unscaled log probabilities of rank `r` and shape
      `[d_0, d_1, ..., d_{r-2}, num_classes]` and dtype `float32` or `float64`.
    labels: `Tensor` of shape `[d_0, d_1, ..., d_{r-2}]` and dtype `int32` or
      `int64`. Each entry in `labels` must be an index in `[0, num_classes)`.
      Other values will result in a loss of 0, but incorrect gradient
      computations.
    name: A name for the operation (optional).

  Returns:
    A `Tensor` of the same shape as `labels` and of the same type as `logits`
    with the softmax cross entropy loss.

  Raises:
    ValueError: If logits are scalars (need to have rank >= 1) or if the rank
      of the labels is not equal to the rank of the labels minus one.
  """
  # TODO(pcmurray) Raise an error when the label is not an index in
  # [0, num_classes). Note: This could break users who call this with bad
  # labels, but disregard the bad results.

  # Reshape logits and labels to rank 2.
  with ops.name_scope(name, "SparseSoftmaxCrossEntropyWithLogits",
                      [labels, logits]):
    labels = ops.convert_to_tensor(labels)
    logits = ops.convert_to_tensor(logits)
    precise_logits = math_ops.cast(logits, dtypes.float32) if (
        dtypes.as_dtype(logits.dtype) == dtypes.float16) else logits

    # Store label shape for result later.
    labels_static_shape = labels.get_shape()
    labels_shape = array_ops.shape(labels)
    if logits.get_shape().ndims is not None and logits.get_shape().ndims == 0:
      raise ValueError("Logits cannot be scalars - received shape %s." %
                       logits.get_shape())
    if logits.get_shape().ndims is not None and (
        labels_static_shape.ndims is not None and
        labels_static_shape.ndims != logits.get_shape().ndims - 1):
      raise ValueError("Rank mismatch: Labels rank (received %s) should equal "
                       "logits rank (received %s) - 1." %
                       (labels_static_shape.ndims, logits.get_shape().ndims))
    # Check if no reshapes are required.
    if logits.get_shape().ndims == 2:
      cost, _ = gen_nn_ops._sparse_softmax_cross_entropy_with_logits(
          precise_logits, labels, name=name)
      if logits.dtype == dtypes.float16:
        return math_ops.cast(cost, dtypes.float16)
      else:
        return cost

    # Reshape logits to 2 dim, labels to 1 dim.
    num_classes = array_ops.gather(array_ops.shape(logits),
                                   array_ops.rank(logits) - 1)
    precise_logits = array_ops.reshape(precise_logits, [-1, num_classes])
    labels = array_ops.reshape(labels, [-1])
    # The second output tensor contains the gradients.  We use it in
    # _CrossEntropyGrad() in nn_grad but not here.
    cost, _ = gen_nn_ops._sparse_softmax_cross_entropy_with_logits(
        precise_logits, labels, name=name)
    cost = array_ops.reshape(cost, labels_shape)
    cost.set_shape(labels_static_shape)
    if logits.dtype == dtypes.float16:
      return math_ops.cast(cost, dtypes.float16)
    else:
      return cost


ops.RegisterShape("SparseSoftmaxCrossEntropyWithLogits")(
    common_shapes.call_cpp_shape_fn)
ops.RegisterShape("SoftmaxCrossEntropyWithLogits")(
    common_shapes.call_cpp_shape_fn)


def avg_pool(value, ksize, strides, padding, data_format="NHWC", name=None):
  """Performs the average pooling on the input.

  Each entry in `output` is the mean of the corresponding size `ksize`
  window in `value`.

  Args:
    value: A 4-D `Tensor` of shape `[batch, height, width, channels]` and type
      `float32`, `float64`, `qint8`, `quint8`, or `qint32`.
    ksize: A list of ints that has length >= 4.
      The size of the window for each dimension of the input tensor.
    strides: A list of ints that has length >= 4.
      The stride of the sliding window for each dimension of the
      input tensor.
    padding: A string, either `'VALID'` or `'SAME'`. The padding algorithm.
      See the [comment here](https://www.tensorflow.org/api_docs/python/nn.html#convolution)
    data_format: A string. 'NHWC' and 'NCHW' are supported.
    name: Optional name for the operation.

  Returns:
    A `Tensor` with the same type as `value`.  The average pooled output tensor.
  """
  with ops.name_scope(name, "AvgPool", [value]) as name:
    value = ops.convert_to_tensor(value, name="input")
    return gen_nn_ops._avg_pool(value,
                                ksize=ksize,
                                strides=strides,
                                padding=padding,
                                data_format=data_format,
                                name=name)


def max_pool(value, ksize, strides, padding, data_format="NHWC", name=None):
  """Performs the max pooling on the input.

  Args:
    value: A 4-D `Tensor` with shape `[batch, height, width, channels]` and
      type `tf.float32`.
    ksize: A list of ints that has length >= 4.  The size of the window for
      each dimension of the input tensor.
    strides: A list of ints that has length >= 4.  The stride of the sliding
      window for each dimension of the input tensor.
    padding: A string, either `'VALID'` or `'SAME'`. The padding algorithm.
      See the [comment here](https://www.tensorflow.org/api_docs/python/nn.html#convolution)
    data_format: A string. 'NHWC' and 'NCHW' are supported.
    name: Optional name for the operation.

  Returns:
    A `Tensor` with type `tf.float32`.  The max pooled output tensor.
  """
  with ops.name_scope(name, "MaxPool", [value]) as name:
    value = ops.convert_to_tensor(value, name="input")
    return gen_nn_ops._max_pool(value,
                                ksize=ksize,
                                strides=strides,
                                padding=padding,
                                data_format=data_format,
                                name=name)


ops.RegisterShape("Relu")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Relu6")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Elu")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Softplus")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Softsign")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("ReluGrad")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Relu6Grad")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("EluGrad")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("SoftplusGrad")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("SoftsignGrad")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("L2Loss")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("LRN")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("LRNGrad")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Softmax")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("LogSoftmax")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("InTopK")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("TopK")(common_shapes.call_cpp_shape_fn)


@ops.RegisterShape("TopKV2")
def _TopKV2Shape(op):
  return common_shapes.call_cpp_shape_fn(op, input_tensors_needed=[1])


ops.RegisterShape("BatchNormWithGlobalNormalization")(
    common_shapes.call_cpp_shape_fn)
ops.RegisterShape("BatchNormWithGlobalNormalizationGrad")(
    common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Conv2D")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("DepthwiseConv2dNative")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("AvgPool")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("MaxPool")(common_shapes.call_cpp_shape_fn)


@ops.RegisterShape("FusedResizeAndPadConv2D")
def _FusedResizeAndPadConv2DShape(op):
  """Shape function for FusedResizeAndPadConv2D op."""
  # The bilinear resize shape calculation.
  input_shape = op.inputs[0].get_shape().with_rank(4)
  unused_size_shape = op.inputs[1].get_shape().merge_with([2])
  size = tensor_util.constant_value(op.inputs[1])
  if size is not None:
    height = size[0]
    width = size[1]
  else:
    height = None
    width = None
  resized_shape = tensor_shape.TensorShape(
      [input_shape[0], height, width, input_shape[3]])

  # Calculates the effect of the padding.
  paddings_shape = op.inputs[2].get_shape().with_rank(2)
  resized_shape = resized_shape.with_rank(paddings_shape[0].value)
  paddings_shape = paddings_shape.merge_with(
      tensor_shape.matrix(resized_shape.ndims, 2))
  paddings = tensor_util.constant_value(op.inputs[2])
  if paddings is None:
    padded_shape = tensor_shape.unknown_shape(ndims=resized_shape.ndims)
  else:
    output_dims = []
    for i, dim in enumerate(resized_shape.dims):
      if paddings[i, 0] < 0 or paddings[i, 1] < 0:
        raise ValueError("paddings must be non-negative")
      output_dims.append(dim + paddings[i, 0] + paddings[i, 1])
    padded_shape = tensor_shape.TensorShape(output_dims)

  # Finally work out the convolution's effect.
  filter_shape = op.inputs[3].get_shape().with_rank(4)

  batch_size = padded_shape[0]
  in_rows = padded_shape[1]
  in_cols = padded_shape[2]

  filter_rows = filter_shape[0]
  filter_cols = filter_shape[1]
  depth_out = filter_shape[3]
  # Check that the input depths are compatible.
  padded_shape[3].assert_is_compatible_with(filter_shape[2])

  stride_b, stride_r, stride_c, stride_d = op.get_attr("strides")

  if stride_b != 1 or stride_d != 1:
    raise ValueError("Current implementation does not yet support "
                     "strides in the batch and depth dimensions.")
  # TODO(mrry,shlens): Raise an error if the stride would cause
  # information in the input to be ignored. This will require a change
  # in the kernel implementation.
  padding = op.get_attr("padding")
  out_rows, out_cols = common_shapes.get2d_conv_output_size(in_rows, in_cols,
                                                            filter_rows,
                                                            filter_cols,
                                                            stride_r,
                                                            stride_c,
                                                            padding)

  output_shape = [batch_size, out_rows, out_cols, depth_out]
  return [tensor_shape.TensorShape(output_shape)]


ops.RegisterShape("MaxPoolWithArgmax")(common_shapes.call_cpp_shape_fn)


@ops.RegisterShape("AvgPoolGrad")
def _AvgPoolGradShape(op):
  return common_shapes.call_cpp_shape_fn(op, input_tensors_needed=[0])


ops.RegisterShape("FractionalMaxPool")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("FractionalAvgPool")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("FractionalMaxPoolGrad")(common_shapes.call_cpp_shape_fn)


@ops.RegisterShape("FractionalAvgPoolGrad")
def _fractional_avg_pool_grad_shape(op):
  return common_shapes.call_cpp_shape_fn(op, input_tensors_needed=[0])


@ops.RegisterShape("Conv2DBackpropFilter")
def _Conv2DBackpropFilterShape(op):
  return common_shapes.call_cpp_shape_fn(op, input_tensors_needed=[1])


@ops.RegisterShape("Conv2DBackpropInput")
def _Conv2DBackpropInputShape(op):
  return common_shapes.call_cpp_shape_fn(op, input_tensors_needed=[0])


@ops.RegisterShape("DepthwiseConv2dNativeBackpropFilter")
def _DepthwiseConv2dNativeBackpropFilterShape(op):
  return common_shapes.call_cpp_shape_fn(op, input_tensors_needed=[1])


@ops.RegisterShape("DepthwiseConv2dNativeBackpropInput")
def _DepthwiseConv2dNativeBackpropInputShape(op):
  return common_shapes.call_cpp_shape_fn(op, input_tensors_needed=[0])


ops.RegisterShape("MaxPoolGrad")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("MaxPoolGradWithArgmax")(common_shapes.call_cpp_shape_fn)


@ops.RegisterStatistics("Conv2D", "flops")
def _calc_conv_flops(graph, node):
  """Calculates the compute resources needed for Conv2D."""
  input_shape = graph_util.tensor_shape_from_node_def_name(graph, node.input[0])
  input_shape.assert_is_fully_defined()
  filter_shape = graph_util.tensor_shape_from_node_def_name(graph,
                                                            node.input[1])
  filter_shape.assert_is_fully_defined()
  output_shape = graph_util.tensor_shape_from_node_def_name(graph, node.name)
  output_shape.assert_is_fully_defined()
  filter_height = int(filter_shape[0])
  filter_width = int(filter_shape[1])
  filter_in_depth = int(filter_shape[2])
  output_count = np.prod(output_shape.as_list())
  return ops.OpStats("flops", (output_count * filter_in_depth * filter_height *
                               filter_width * 2))


@ops.RegisterStatistics("Conv2D", "weight_parameters")
def _calc_conv_weight_params(graph, node):
  """Calculates the on-disk size of the weights for Conv2D."""
  input_shape = graph_util.tensor_shape_from_node_def_name(graph, node.input[0])
  input_shape.assert_is_fully_defined()
  filter_shape = graph_util.tensor_shape_from_node_def_name(graph,
                                                            node.input[1])
  filter_shape.assert_is_fully_defined()
  output_shape = graph_util.tensor_shape_from_node_def_name(graph, node.name)
  output_shape.assert_is_fully_defined()
  filter_height = int(filter_shape[0])
  filter_width = int(filter_shape[1])
  filter_in_depth = int(filter_shape[2])
  filter_out_depth = int(filter_shape[3])
  return ops.OpStats("weight_parameters", (filter_height * filter_width *
                                           filter_in_depth * filter_out_depth))


@ops.RegisterStatistics("DepthwiseConv2dNative", "flops")
def _calc_depthwise_conv_flops(graph, node):
  """Calculates the compute resources needed for DepthwiseConv2dNative."""
  input_shape = graph_util.tensor_shape_from_node_def_name(graph, node.input[0])
  input_shape.assert_is_fully_defined()
  filter_shape = graph_util.tensor_shape_from_node_def_name(graph,
                                                            node.input[1])
  filter_shape.assert_is_fully_defined()
  output_shape = graph_util.tensor_shape_from_node_def_name(graph, node.name)
  output_shape.assert_is_fully_defined()
  filter_height = int(filter_shape[0])
  filter_width = int(filter_shape[1])
  output_count = np.prod(output_shape.as_list())
  return ops.OpStats("flops", (output_count * filter_height * filter_width * 2))


@ops.RegisterStatistics("DepthwiseConv2dNative", "weight_parameters")
def _calc_depthwise_conv_weight_params(graph, node):
  """Calculates the on-disk size of the weights for DepthwiseConv2dNative."""
  input_shape = graph_util.tensor_shape_from_node_def_name(graph, node.input[0])
  input_shape.assert_is_fully_defined()
  filter_shape = graph_util.tensor_shape_from_node_def_name(graph,
                                                            node.input[1])
  filter_shape.assert_is_fully_defined()
  output_shape = graph_util.tensor_shape_from_node_def_name(graph, node.name)
  output_shape.assert_is_fully_defined()
  filter_height = int(filter_shape[0])
  filter_width = int(filter_shape[1])
  filter_in_depth = int(filter_shape[2])
  filter_channel_multiplier = int(filter_shape[3])
  return ops.OpStats("weight_parameters", (filter_height * filter_width *
                                           filter_in_depth *
                                           filter_channel_multiplier))


ops.RegisterShape("Conv3D")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("MaxPool3D")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("AvgPool3D")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Conv3DBackpropFilter")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Conv3DBackpropInput")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Conv3DBackpropFilterV2")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Conv3DBackpropInputV2")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("AvgPool3DGrad")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("MaxPool3DGrad")(common_shapes.call_cpp_shape_fn)


@ops.RegisterStatistics("BiasAdd", "flops")
def _calc_bias_add_flops(graph, node):
  """Calculates the computing needed for BiasAdd."""
  input_shape = graph_util.tensor_shape_from_node_def_name(graph, node.input[0])
  input_shape.assert_is_fully_defined()
  input_count = np.prod(input_shape.as_list())
  return ops.OpStats("flops", input_count)


@ops.RegisterStatistics("BiasAdd", "weight_parameters")
def _calc_bias_add_weight_params(graph, node):
  """Calculates the on-disk weight parameters for BiasAdd."""
  bias_shape = graph_util.tensor_shape_from_node_def_name(graph, node.input[1])
  bias_shape.assert_is_fully_defined()
  bias_count = np.prod(bias_shape.as_list())
  return ops.OpStats("weight_parameters", bias_count)


def xw_plus_b(x, weights, biases, name=None):  # pylint: disable=invalid-name
  """Computes matmul(x, weights) + biases.

  Args:
    x: a 2D tensor.  Dimensions typically: batch, in_units
    weights: a 2D tensor.  Dimensions typically: in_units, out_units
    biases: a 1D tensor.  Dimensions: out_units
    name: A name for the operation (optional).  If not specified
      "xw_plus_b" is used.

  Returns:
    A 2-D Tensor computing matmul(x, weights) + biases.
    Dimensions typically: batch, out_units.
  """
  with ops.name_scope(name, "xw_plus_b", [x, weights, biases]) as name:
    x = ops.convert_to_tensor(x, name="x")
    weights = ops.convert_to_tensor(weights, name="weights")
    biases = ops.convert_to_tensor(biases, name="biases")
    mm = math_ops.matmul(x, weights)
    return bias_add(mm, biases, name=name)


def xw_plus_b_v1(x, weights, biases, name=None):  # pylint: disable=invalid-name
  """Computes matmul(x, weights) + biases.

  This is a deprecated version of that will soon be removed.

  Args:
    x: a 2D tensor.  Dimensions typically: batch, in_units
    weights: a 2D tensor.  Dimensions typically: in_units, out_units
    biases: a 1D tensor.  Dimensions: out_units
    name: A name for the operation (optional).  If not specified
      "xw_plus_b_v1" is used.

  Returns:
    A 2-D Tensor computing matmul(x, weights) + biases.
    Dimensions typically: batch, out_units.
  """
  with ops.name_scope(name, "xw_plus_b_v1", [x, weights, biases]) as name:
    x = ops.convert_to_tensor(x, name="x")
    weights = ops.convert_to_tensor(weights, name="weights")
    biases = ops.convert_to_tensor(biases, name="biases")
    mm = math_ops.matmul(x, weights)
    return bias_add_v1(mm, biases, name=name)


# pylint: disable=invalid-name
def dropout(x, keep_prob, noise_shape=None, seed=None, name=None):
  """Computes dropout.

  With probability `keep_prob`, outputs the input element scaled up by
  `1 / keep_prob`, otherwise outputs `0`.  The scaling is so that the expected
  sum is unchanged.

  By default, each element is kept or dropped independently.  If `noise_shape`
  is specified, it must be
  [broadcastable](http://docs.scipy.org/doc/numpy/user/basics.broadcasting.html)
  to the shape of `x`, and only dimensions with `noise_shape[i] == shape(x)[i]`
  will make independent decisions.  For example, if `shape(x) = [k, l, m, n]`
  and `noise_shape = [k, 1, 1, n]`, each batch and channel component will be
  kept independently and each row and column will be kept or not kept together.

  Args:
    x: A tensor.
    keep_prob: A scalar `Tensor` with the same type as x. The probability
      that each element is kept.
    noise_shape: A 1-D `Tensor` of type `int32`, representing the
      shape for randomly generated keep/drop flags.
    seed: A Python integer. Used to create random seeds. See
      [`set_random_seed`](../../api_docs/python/constant_op.md#set_random_seed)
      for behavior.
    name: A name for this operation (optional).

  Returns:
    A Tensor of the same shape of `x`.

  Raises:
    ValueError: If `keep_prob` is not in `(0, 1]`.
  """
  with ops.name_scope(name, "dropout", [x]) as name:
    x = ops.convert_to_tensor(x, name="x")
    if isinstance(keep_prob, numbers.Real) and not 0 < keep_prob <= 1:
      raise ValueError("keep_prob must be a scalar tensor or a float in the "
                       "range (0, 1], got %g" % keep_prob)
    keep_prob = ops.convert_to_tensor(keep_prob,
                                      dtype=x.dtype,
                                      name="keep_prob")
    keep_prob.get_shape().assert_is_compatible_with(tensor_shape.scalar())

    # Do nothing if we know keep_prob == 1
    if tensor_util.constant_value(keep_prob) == 1:
      return x

    noise_shape = noise_shape if noise_shape is not None else array_ops.shape(x)
    # uniform [keep_prob, 1.0 + keep_prob)
    random_tensor = keep_prob
    random_tensor += random_ops.random_uniform(noise_shape,
                                               seed=seed,
                                               dtype=x.dtype)
    # 0. if [keep_prob, 1.0) and 1. if [1.0, 1.0 + keep_prob)
    binary_tensor = math_ops.floor(random_tensor)
    ret = math_ops.div(x, keep_prob) * binary_tensor
    ret.set_shape(x.get_shape())
    return ret


def top_k(input, k=1, sorted=True, name=None):
  """Finds values and indices of the `k` largest entries for the last dimension.

  If the input is a vector (rank-1), finds the `k` largest entries in the vector
  and outputs their values and indices as vectors.  Thus `values[j]` is the
  `j`-th largest entry in `input`, and its index is `indices[j]`.

  For matrices (resp. higher rank input), computes the top `k` entries in each
  row (resp. vector along the last dimension).  Thus,

      values.shape = indices.shape = input.shape[:-1] + [k]

  If two elements are equal, the lower-index element appears first.

  Args:
    input: 1-D or higher `Tensor` with last dimension at least `k`.
    k: 0-D `int32` `Tensor`.  Number of top elements to look for along the last
      dimension (along each row for matrices).
    sorted: If true the resulting `k` elements will be sorted by the values in
      descending order.
    name: Optional name for the operation.

  Returns:
    values: The `k` largest elements along each last dimensional slice.
    indices: The indices of `values` within the last dimension of `input`.
  """
  return gen_nn_ops._top_kv2(input, k=k, sorted=sorted, name=name)


def conv1d(value, filters, stride, padding,
           use_cudnn_on_gpu=None, data_format=None,
           name=None):
  """Computes a 1-D convolution given 3-D input and filter tensors.

  Given an input tensor of shape [batch, in_width, in_channels]
  and a filter / kernel tensor of shape
  [filter_width, in_channels, out_channels], this op reshapes
  the arguments to pass them to conv2d to perform the equivalent
  convolution operation.

  Internally, this op reshapes the input tensors and invokes
  `tf.nn.conv2d`.  A tensor of shape [batch, in_width, in_channels]
  is reshaped to [batch, 1, in_width, in_channels], and the filter
  is reshaped to [1, filter_width, in_channels, out_channels].
  The result is then reshaped back to [batch, out_width, out_channels]
  (where out_width is a function of the stride and padding as in
  conv2d) and returned to the caller.

  Args:
    value: A 3D `Tensor`.  Must be of type `float32` or `float64`.
    filters: A 3D `Tensor`.  Must have the same type as `input`.
    stride: An `integer`.  The number of entries by which
      the filter is moved right at each step.
    padding: 'SAME' or 'VALID'
    use_cudnn_on_gpu: An optional `bool`.  Defaults to `True`.
    data_format: An optional `string` from `"NHWC", "NCHW"`.  Defaults
      to `"NHWC"`, the data is stored in the order of
      [batch, in_width, in_channels].  The `"NCHW"` format stores
      data as [batch, in_channels, in_width].
    name: A name for the operation (optional).

  Returns:
    A `Tensor`.  Has the same type as input.
  """
  with ops.name_scope(name, "conv1d", [value, filters]) as name:
    # Reshape the input tensor to [batch, 1, in_width, in_channels]
    value = array_ops.expand_dims(value, 1)
    # And reshape the filter to [1, filter_width, in_channels, out_channels]
    filters = array_ops.expand_dims(filters, 0)
    result = gen_nn_ops.conv2d(value, filters, [1, 1, stride, 1], padding,
                               use_cudnn_on_gpu=use_cudnn_on_gpu,
                               data_format=data_format)
    return array_ops.squeeze(result, [1])


ops.RegisterShape("Dilation2D")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Dilation2DBackpropInput")(common_shapes.call_cpp_shape_fn)
ops.RegisterShape("Dilation2DBackpropFilter")(common_shapes.call_cpp_shape_fn)


@ops.RegisterStatistics("Dilation2D", "flops")
def _calc_dilation2d_flops(graph, node):
  """Calculates the compute resources needed for Dilation2D."""
  input_shape = graph_util.tensor_shape_from_node_def_name(graph, node.input[0])
  input_shape.assert_is_fully_defined()
  filter_shape = graph_util.tensor_shape_from_node_def_name(graph,
                                                            node.input[1])
  filter_shape.assert_is_fully_defined()
  output_shape = graph_util.tensor_shape_from_node_def_name(graph, node.name)
  output_shape.assert_is_fully_defined()
  filter_height = int(filter_shape[0])
  filter_width = int(filter_shape[1])
  output_count = np.prod(output_shape.as_list())
  return ops.OpStats("flops", (output_count * filter_height * filter_width * 2))


@ops.RegisterStatistics("Dilation2D", "weight_parameters")
def _calc_dilation2d_weight_params(graph, node):
  """Calculates the on-disk size of the weights for Dilation2D."""
  filter_shape = graph_util.tensor_shape_from_node_def_name(graph,
                                                            node.input[1])
  filter_shape.assert_is_fully_defined()
  filter_height = int(filter_shape[0])
  filter_width = int(filter_shape[1])
  filter_depth = int(filter_shape[2])
  return ops.OpStats("weight_parameters",
                     (filter_height * filter_width * filter_depth))


def erosion2d(value, kernel, strides, rates, padding, name=None):
  """Computes the grayscale erosion of 4-D `value` and 3-D `kernel` tensors.

  The `value` tensor has shape `[batch, in_height, in_width, depth]` and the
  `kernel` tensor has shape `[kernel_height, kernel_width, depth]`, i.e.,
  each input channel is processed independently of the others with its own
  structuring function. The `output` tensor has shape
  `[batch, out_height, out_width, depth]`. The spatial dimensions of the
  output tensor depend on the `padding` algorithm. We currently only support the
  default "NHWC" `data_format`.

  In detail, the grayscale morphological 2-D erosion is given by:

      output[b, y, x, c] =
         min_{dy, dx} value[b,
                            strides[1] * y - rates[1] * dy,
                            strides[2] * x - rates[2] * dx,
                            c] -
                      kernel[dy, dx, c]

  Duality: The erosion of `value` by the `kernel` is equal to the negation of
  the dilation of `-value` by the reflected `kernel`.

  Args:
    value: A `Tensor`. 4-D with shape `[batch, in_height, in_width, depth]`.
    kernel: A `Tensor`. Must have the same type as `value`.
      3-D with shape `[kernel_height, kernel_width, depth]`.
    strides: A list of `ints` that has length `>= 4`.
      1-D of length 4. The stride of the sliding window for each dimension of
      the input tensor. Must be: `[1, stride_height, stride_width, 1]`.
    rates: A list of `ints` that has length `>= 4`.
      1-D of length 4. The input stride for atrous morphological dilation.
      Must be: `[1, rate_height, rate_width, 1]`.
    padding: A `string` from: `"SAME", "VALID"`.
      The type of padding algorithm to use.
    name: A name for the operation (optional). If not specified "erosion2d"
      is used.

  Returns:
    A `Tensor`. Has the same type as `value`.
    4-D with shape `[batch, out_height, out_width, depth]`.

  Raises:
    ValueError: If the `value` depth does not match `kernel`' shape, or if
      padding is other than `'VALID'` or `'SAME'`.
  """
  with ops.name_scope(name, "erosion2d", [value, kernel]) as name:
    # Reduce erosion to dilation by duality.
    return math_ops.neg(gen_nn_ops.dilation2d(input=math_ops.neg(value),
                                              filter=array_ops.reverse(
                                                  kernel, [True, True, False]),
                                              strides=strides,
                                              rates=rates,
                                              padding=padding,
                                              name=name))

# pylint: enable=invalid-name