resnet_my.py

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

import tensorflow as tf

_BATCH_NORM_DECAY = 0.997
_BATCH_NORM_EPSILON = 1e-5
DEFAULT_VERSION = 2
DEFAULT_DTYPE = tf.float32
CASTABLE_TYPES = (tf.float16,)
ALLOWED_TYPES = (DEFAULT_DTYPE,) + CASTABLE_TYPES
data_format = 'channels_last'
num_classes=10
block_strides=[1,2,2,2]
num_filters=[64,128,256,512]
def batch_norm(inputs, training, data_format):
  """Performs a batch normalization using a standard set of parameters."""
  # We set fused=True for a significant performance boost. See
  # https://www.tensorflow.org/performance/performance_guide#common_fused_ops
  return tf.layers.batch_normalization(
      inputs=inputs, axis=1 if data_format == 'channels_first' else 3,
      momentum=_BATCH_NORM_DECAY, epsilon=_BATCH_NORM_EPSILON, center=True,
      scale=True, training=training, fused=True)
def fixed_padding(inputs, kernel_size, data_format):
  """Pads the input along the spatial dimensions independently of input size.

  Args:
    inputs: A tensor of size [batch, channels, height_in, width_in] or
      [batch, height_in, width_in, channels] depending on data_format.
    kernel_size: The kernel to be used in the conv2d or max_pool2d operation.
                 Should be a positive integer.
    data_format: The input format ('channels_last' or 'channels_first').

  Returns:
    A tensor with the same format as the input with the data either intact
    (if kernel_size == 1) or padded (if kernel_size > 1).
  """
  pad_total = kernel_size - 1
  pad_beg = pad_total // 2
  pad_end = pad_total - pad_beg

  if data_format == 'channels_first':
    padded_inputs = tf.pad(inputs, [[0, 0], [0, 0],
                                    [pad_beg, pad_end], [pad_beg, pad_end]])
  else:
    padded_inputs = tf.pad(inputs, [[0, 0], [pad_beg, pad_end],
                                    [pad_beg, pad_end], [0, 0]])
  return padded_inputs


def conv2d_fixed_padding(inputs, filters, kernel_size, strides, data_format):
  """Strided 2-D convolution with explicit padding."""
  # The padding is consistent and is based only on `kernel_size`, not on the
  # dimensions of `inputs` (as opposed to using `tf.layers.conv2d` alone).
  if strides > 1:
    inputs = fixed_padding(inputs, kernel_size, data_format)

  return tf.layers.conv2d(
      inputs=inputs, filters=filters, kernel_size=kernel_size, strides=strides,
      padding=('SAME' if strides == 1 else 'VALID'), use_bias=False,
      kernel_initializer=tf.variance_scaling_initializer(),
      data_format=data_format)


################################################################################
# ResNet block definitions.
################################################################################
def _building_block_v1(inputs, filters, training, projection_shortcut, strides,
                       data_format):
  """A single block for ResNet v1, without a bottleneck.

  Convolution then batch normalization then ReLU as described by:
    Deep Residual Learning for Image Recognition
    https://arxiv.org/pdf/1512.03385.pdf
    by Kaiming He, Xiangyu Zhang, Shaoqing Ren, and Jian Sun, Dec 2015.

  Args:
    inputs: A tensor of size [batch, channels, height_in, width_in] or
      [batch, height_in, width_in, channels] depending on data_format.
    filters: The number of filters for the convolutions.
    training: A Boolean for whether the model is in training or inference
      mode. Needed for batch normalization.
    projection_shortcut: The function to use for projection shortcuts
      (typically a 1x1 convolution when downsampling the input).
    strides: The block's stride. If greater than 1, this block will ultimately
      downsample the input.
    data_format: The input format ('channels_last' or 'channels_first').

  Returns:
    The output tensor of the block; shape should match inputs.
  """
  shortcut = inputs

  if projection_shortcut is not None:
    shortcut = projection_shortcut(inputs)
    shortcut = batch_norm(inputs=shortcut, training=training,
                          data_format=data_format)

  inputs = conv2d_fixed_padding(
      inputs=inputs, filters=filters, kernel_size=3, strides=strides,
      data_format=data_format)
  inputs = batch_norm(inputs, training, data_format)
  inputs = tf.nn.relu(inputs)

  inputs = conv2d_fixed_padding(
      inputs=inputs, filters=filters, kernel_size=3, strides=1,
      data_format=data_format)
  inputs = batch_norm(inputs, training, data_format)
  inputs += shortcut
  inputs = tf.nn.relu(inputs)

  return inputs


def _building_block_v2(inputs, filters, training, projection_shortcut, strides,
                       data_format):
  """A single block for ResNet v2, without a bottleneck.

  Batch normalization then ReLu then convolution as described by:
    Identity Mappings in Deep Residual Networks
    https://arxiv.org/pdf/1603.05027.pdf
    by Kaiming He, Xiangyu Zhang, Shaoqing Ren, and Jian Sun, Jul 2016.

  Args:
    inputs: A tensor of size [batch, channels, height_in, width_in] or
      [batch, height_in, width_in, channels] depending on data_format.
    filters: The number of filters for the convolutions.
    training: A Boolean for whether the model is in training or inference
      mode. Needed for batch normalization.
    projection_shortcut: The function to use for projection shortcuts
      (typically a 1x1 convolution when downsampling the input).
    strides: The block's stride. If greater than 1, this block will ultimately
      downsample the input.
    data_format: The input format ('channels_last' or 'channels_first').

  Returns:
    The output tensor of the block; shape should match inputs.
  """
  shortcut = inputs
  inputs = batch_norm(inputs, training, data_format)
  inputs = tf.nn.relu(inputs)

  # The projection shortcut should come after the first batch norm and ReLU
  # since it performs a 1x1 convolution.
  if projection_shortcut is not None:
    shortcut = projection_shortcut(inputs)

  inputs = conv2d_fixed_padding(
      inputs=inputs, filters=filters, kernel_size=3, strides=strides,
      data_format=data_format)

  inputs = batch_norm(inputs, training, data_format)
  inputs = tf.nn.relu(inputs)
  inputs = conv2d_fixed_padding(
      inputs=inputs, filters=filters, kernel_size=3, strides=1,
      data_format=data_format)

  return inputs + shortcut


def _bottleneck_block_v1(inputs, filters, training, projection_shortcut,
                         strides, data_format):
  """A single block for ResNet v1, with a bottleneck.

  Similar to _building_block_v1(), except using the "bottleneck" blocks
  described in:
    Convolution then batch normalization then ReLU as described by:
      Deep Residual Learning for Image Recognition
      https://arxiv.org/pdf/1512.03385.pdf
      by Kaiming He, Xiangyu Zhang, Shaoqing Ren, and Jian Sun, Dec 2015.

  Args:
    inputs: A tensor of size [batch, channels, height_in, width_in] or
      [batch, height_in, width_in, channels] depending on data_format.
    filters: The number of filters for the convolutions.
    training: A Boolean for whether the model is in training or inference
      mode. Needed for batch normalization.
    projection_shortcut: The function to use for projection shortcuts
      (typically a 1x1 convolution when downsampling the input).
    strides: The block's stride. If greater than 1, this block will ultimately
      downsample the input.
    data_format: The input format ('channels_last' or 'channels_first').

  Returns:
    The output tensor of the block; shape should match inputs.
  """
  shortcut = inputs

  if projection_shortcut is not None:
    shortcut = projection_shortcut(inputs)
    shortcut = batch_norm(inputs=shortcut, training=training,
                          data_format=data_format)

  inputs = conv2d_fixed_padding(
      inputs=inputs, filters=filters, kernel_size=1, strides=1,
      data_format=data_format)
  inputs = batch_norm(inputs, training, data_format)
  inputs = tf.nn.relu(inputs)

  inputs = conv2d_fixed_padding(
      inputs=inputs, filters=filters, kernel_size=3, strides=strides,
      data_format=data_format)
  inputs = batch_norm(inputs, training, data_format)
  inputs = tf.nn.relu(inputs)

  inputs = conv2d_fixed_padding(
      inputs=inputs, filters=4 * filters, kernel_size=1, strides=1,
      data_format=data_format)
  inputs = batch_norm(inputs, training, data_format)
  inputs += shortcut
  inputs = tf.nn.relu(inputs)

  return inputs


def _bottleneck_block_v2(inputs, filters, training, projection_shortcut,
                         strides, data_format):
  """A single block for ResNet v2, without a bottleneck.

  Similar to _building_block_v2(), except using the "bottleneck" blocks
  described in:
    Convolution then batch normalization then ReLU as described by:
      Deep Residual Learning for Image Recognition
      https://arxiv.org/pdf/1512.03385.pdf
      by Kaiming He, Xiangyu Zhang, Shaoqing Ren, and Jian Sun, Dec 2015.

  Adapted to the ordering conventions of:
    Batch normalization then ReLu then convolution as described by:
      Identity Mappings in Deep Residual Networks
      https://arxiv.org/pdf/1603.05027.pdf
      by Kaiming He, Xiangyu Zhang, Shaoqing Ren, and Jian Sun, Jul 2016.

  Args:
    inputs: A tensor of size [batch, channels, height_in, width_in] or
      [batch, height_in, width_in, channels] depending on data_format.
    filters: The number of filters for the convolutions.
    training: A Boolean for whether the model is in training or inference
      mode. Needed for batch normalization.
    projection_shortcut: The function to use for projection shortcuts
      (typically a 1x1 convolution when downsampling the input).
    strides: The block's stride. If greater than 1, this block will ultimately
      downsample the input.
    data_format: The input format ('channels_last' or 'channels_first').

  Returns:
    The output tensor of the block; shape should match inputs.
  """
  shortcut = inputs
  inputs = batch_norm(inputs, training, data_format)
  inputs = tf.nn.relu(inputs)

  # The projection shortcut should come after the first batch norm and ReLU
  # since it performs a 1x1 convolution.
  if projection_shortcut is not None:
    shortcut = projection_shortcut(inputs)

  inputs = conv2d_fixed_padding(
      inputs=inputs, filters=filters, kernel_size=1, strides=1,
      data_format=data_format)

  inputs = batch_norm(inputs, training, data_format)
  inputs = tf.nn.relu(inputs)
  inputs = conv2d_fixed_padding(
      inputs=inputs, filters=filters, kernel_size=3, strides=strides,
      data_format=data_format)

  inputs = batch_norm(inputs, training, data_format)
  inputs = tf.nn.relu(inputs)
  inputs = conv2d_fixed_padding(
      inputs=inputs, filters=4 * filters, kernel_size=1, strides=1,
      data_format=data_format)

  return inputs + shortcut
def block_layer(inputs, filters, bottleneck, block_fn, blocks, strides,
                training, name, data_format):
  """Creates one layer of blocks for the ResNet model.

  Args:
    inputs: A tensor of size [batch, channels, height_in, width_in] or
      [batch, height_in, width_in, channels] depending on data_format.
    filters: The number of filters for the first convolution of the layer.
    bottleneck: Is the block created a bottleneck block.
    block_fn: The block to use within the model, either `building_block` or
      `bottleneck_block`.
    blocks: The number of blocks contained in the layer.
    strides: The stride to use for the first convolution of the layer. If
      greater than 1, this layer will ultimately downsample the input.
    training: Either True or False, whether we are currently training the
      model. Needed for batch norm.
    name: A string name for the tensor output of the block layer.
    data_format: The input format ('channels_last' or 'channels_first').

  Returns:
    The output tensor of the block layer.
  """

  # Bottleneck blocks end with 4x the number of filters as they start with
  filters_out = filters * 4 if bottleneck else filters

  def projection_shortcut(inputs):
    return conv2d_fixed_padding(
        inputs=inputs, filters=filters_out, kernel_size=1, strides=strides,
        data_format=data_format)

  # Only the first block per block_layer uses projection_shortcut and strides
  inputs = block_fn(inputs, filters, training, projection_shortcut, strides,
                    data_format)

  for _ in range(1, blocks):
    inputs = block_fn(inputs, filters, training, None, 1, data_format)

  return tf.identity(inputs, name)

def _custom_dtype_getter(getter, name, shape=None, dtype=DEFAULT_DTYPE,
                           *args, **kwargs):
    """Creates variables in fp32, then casts to fp16 if necessary.

    This function is a custom getter. A custom getter is a function with the
    same signature as tf.get_variable, except it has an additional getter
    parameter. Custom getters can be passed as the `custom_getter` parameter of
    tf.variable_scope. Then, tf.get_variable will call the custom getter,
    instead of directly getting a variable itself. This can be used to change
    the types of variables that are retrieved with tf.get_variable.
    The `getter` parameter is the underlying variable getter, that would have
    been called if no custom getter was used. Custom getters typically get a
    variable with `getter`, then modify it in some way.

    This custom getter will create an fp32 variable. If a low precision
    (e.g. float16) variable was requested it will then cast the variable to the
    requested dtype. The reason we do not directly create variables in low
    precision dtypes is that applying small gradients to such variables may
    cause the variable not to change.

    Args:
      getter: The underlying variable getter, that has the same signature as
        tf.get_variable and returns a variable.
      name: The name of the variable to get.
      shape: The shape of the variable to get.
      dtype: The dtype of the variable to get. Note that if this is a low
        precision dtype, the variable will be created as a tf.float32 variable,
        then cast to the appropriate dtype
      *args: Additional arguments to pass unmodified to getter.
      **kwargs: Additional keyword arguments to pass unmodified to getter.

    Returns:
      A variable which is cast to fp16 if necessary.
    """

    if dtype in CASTABLE_TYPES:
      var = getter(name, shape, tf.float32, *args, **kwargs)
      return tf.cast(var, dtype=dtype, name=name + '_cast')
    else:
      return getter(name, shape, dtype, *args, **kwargs)

def _model_variable_scope():
    """Returns a variable scope that the model should be created under.

    If self.dtype is a castable type, model variable will be created in fp32
    then cast to self.dtype before being used.

    Returns:
      A variable scope for the model.
    """

    return tf.variable_scope('resnet_model',
                             custom_getter=_custom_dtype_getter)
def resnet50(inputs, training):
    """Add operations to classify a batch of input images.

    Args:
      inputs: A Tensor representing a batch of input images.
      training: A boolean. Set to True to add operations required only when
        training the classifier.

    Returns:
      A logits Tensor with shape [<batch_size>, self.num_classes].
    """

    with _model_variable_scope():
      if data_format == 'channels_first':
        # Convert the inputs from channels_last (NHWC) to channels_first (NCHW).
        # This provides a large performance boost on GPU. See
        # https://www.tensorflow.org/performance/performance_guide#data_formats
        inputs = tf.transpose(inputs, [0, 3, 1, 2])

      inputs = conv2d_fixed_padding(
          inputs=inputs, filters=64, kernel_size=7,
          strides=2, data_format=data_format)
      inputs = tf.identity(inputs, 'initial_conv')

      # We do not include batch normalization or activation functions in V2
      # for the initial conv1 because the first ResNet unit will perform these
      # for both the shortcut and non-shortcut paths as part of the first
      # block's projection. Cf. Appendix of [2].
      # if self.resnet_version == 1:
      inputs = batch_norm(inputs, training, data_format)
      inputs = tf.nn.relu(inputs)

      # if self.first_pool_size:
      inputs = tf.layers.max_pooling2d(
            inputs=inputs, pool_size=3,
            strides=2, padding='VALID',
            data_format=data_format)
      inputs = tf.identity(inputs, 'initial_max_pool')

      for i, num_blocks in enumerate([3,4,6,3]):
        inputs = block_layer(
            inputs=inputs, filters=num_filters[i], bottleneck=True,
            block_fn=_bottleneck_block_v1, blocks=num_blocks,
            strides=block_strides[i], training=training,
            name='block_layer{}'.format(i + 1), data_format=data_format)
      # Only apply the BN and ReLU for model that does pre_activation in each
      # building/bottleneck block, eg resnet V2.
      # if self.pre_activation:
      #   inputs = batch_norm(inputs, training, self.data_format)
      #   inputs = tf.nn.relu(inputs)

      # The current top layer has shape
      # `batch_size x pool_size x pool_size x final_size`.
      # ResNet does an Average Pooling layer over pool_size,
      # but that is the same as doing a reduce_mean. We do a reduce_mean
      # here because it performs better than AveragePooling2D.
      axes = [2, 3] if data_format == 'channels_first' else [1, 2]
      inputs = tf.reduce_mean(inputs, axes, keep_dims=True)
      inputs = tf.identity(inputs, 'final_reduce_mean')
      inputs = tf.reshape(inputs, [-1, 2048])
      inputs = tf.layers.dense(inputs=inputs, units=num_classes)
      inputs = tf.identity(inputs, 'final_dense')
    return inputs