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future_keras.py
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future_keras.py
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from keras import backend as K
from keras.layers import Conv2D
from keras import activations
from keras import initializers
from keras import regularizers
from keras import constraints
from keras.engine import InputSpec
from keras.utils import conv_utils
class DepthwiseConv2D(Conv2D):
"""Depthwise separable 2D convolution.
Depthwise Separable convolutions consists in performing
just the first step in a depthwise spatial convolution
(which acts on each input channel separately).
The `depth_multiplier` argument controls how many
output channels are generated per input channel in the depthwise step.
# Arguments
kernel_size: An integer or tuple/list of 2 integers, specifying the
width and height of the 2D convolution window.
Can be a single integer to specify the same value for
all spatial dimensions.
strides: An integer or tuple/list of 2 integers,
specifying the strides of the convolution along the width and height.
Can be a single integer to specify the same value for
all spatial dimensions.
Specifying any stride value != 1 is incompatible with specifying
any `dilation_rate` value != 1.
padding: one of `'valid'` or `'same'` (case-insensitive).
depth_multiplier: The number of depthwise convolution output channels
for each input channel.
The total number of depthwise convolution output
channels will be equal to `filters_in * depth_multiplier`.
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, height, width, channels)` while `channels_first`
corresponds to inputs with shape
`(batch, channels, height, width)`.
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'.
activation: Activation function to use
(see [activations](../activations.md)).
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.
depthwise_initializer: Initializer for the depthwise kernel matrix
(see [initializers](../initializers.md)).
bias_initializer: Initializer for the bias vector
(see [initializers](../initializers.md)).
depthwise_regularizer: Regularizer function applied to
the depthwise kernel matrix
(see [regularizer](../regularizers.md)).
bias_regularizer: Regularizer function applied to the bias vector
(see [regularizer](../regularizers.md)).
activity_regularizer: Regularizer function applied to
the output of the layer (its 'activation').
(see [regularizer](../regularizers.md)).
depthwise_constraint: Constraint function applied to
the depthwise kernel matrix
(see [constraints](../constraints.md)).
bias_constraint: Constraint function applied to the bias vector
(see [constraints](../constraints.md)).
# Input shape
4D tensor with shape:
`[batch, channels, rows, cols]` if data_format='channels_first'
or 4D tensor with shape:
`[batch, rows, cols, channels]` if data_format='channels_last'.
# Output shape
4D tensor with shape:
`[batch, filters, new_rows, new_cols]` if data_format='channels_first'
or 4D tensor with shape:
`[batch, new_rows, new_cols, filters]` if data_format='channels_last'.
`rows` and `cols` values might have changed due to padding.
"""
def __init__(self,
kernel_size,
strides=(1, 1),
padding='valid',
depth_multiplier=1,
data_format=None,
activation=None,
use_bias=True,
depthwise_initializer='glorot_uniform',
bias_initializer='zeros',
depthwise_regularizer=None,
bias_regularizer=None,
activity_regularizer=None,
depthwise_constraint=None,
bias_constraint=None,
**kwargs):
super(DepthwiseConv2D, self).__init__(
filters=None,
kernel_size=kernel_size,
strides=strides,
padding=padding,
data_format=data_format,
activation=activation,
use_bias=use_bias,
bias_regularizer=bias_regularizer,
activity_regularizer=activity_regularizer,
bias_constraint=bias_constraint,
**kwargs)
self.depth_multiplier = depth_multiplier
self.depthwise_initializer = initializers.get(depthwise_initializer)
self.depthwise_regularizer = regularizers.get(depthwise_regularizer)
self.depthwise_constraint = constraints.get(depthwise_constraint)
self.bias_initializer = initializers.get(bias_initializer)
def build(self, input_shape):
if len(input_shape) < 4:
raise ValueError('Inputs to `DepthwiseConv2D` should have rank 4. '
'Received input shape:', str(input_shape))
if self.data_format == 'channels_first':
channel_axis = 1
else:
channel_axis = 3
if input_shape[channel_axis] is None:
raise ValueError('The channel dimension of the inputs to '
'`DepthwiseConv2D` '
'should be defined. Found `None`.')
input_dim = int(input_shape[channel_axis])
depthwise_kernel_shape = (self.kernel_size[0],
self.kernel_size[1],
input_dim,
self.depth_multiplier)
self.depthwise_kernel = self.add_weight(
shape=depthwise_kernel_shape,
initializer=self.depthwise_initializer,
name='depthwise_kernel',
regularizer=self.depthwise_regularizer,
constraint=self.depthwise_constraint)
if self.use_bias:
self.bias = self.add_weight(shape=(input_dim * self.depth_multiplier,),
initializer=self.bias_initializer,
name='bias',
regularizer=self.bias_regularizer,
constraint=self.bias_constraint)
else:
self.bias = None
# Set input spec.
self.input_spec = InputSpec(ndim=4, axes={channel_axis: input_dim})
self.built = True
def call(self, inputs, training=None):
outputs = K.depthwise_conv2d(
inputs,
self.depthwise_kernel,
strides=self.strides,
padding=self.padding,
dilation_rate=self.dilation_rate,
data_format=self.data_format)
if self.bias:
outputs = K.bias_add(
outputs,
self.bias,
data_format=self.data_format)
if self.activation is not None:
return self.activation(outputs)
return outputs
def compute_output_shape(self, input_shape):
if self.data_format == 'channels_first':
rows = input_shape[2]
cols = input_shape[3]
out_filters = input_shape[1] * self.depth_multiplier
elif self.data_format == 'channels_last':
rows = input_shape[1]
cols = input_shape[2]
out_filters = input_shape[3] * self.depth_multiplier
rows = conv_utils.conv_output_length(rows, self.kernel_size[0],
self.padding,
self.strides[0])
cols = conv_utils.conv_output_length(cols, self.kernel_size[1],
self.padding,
self.strides[1])
if self.data_format == 'channels_first':
return (input_shape[0], out_filters, rows, cols)
elif self.data_format == 'channels_last':
return (input_shape[0], rows, cols, out_filters)
def get_config(self):
config = super(DepthwiseConv2D, self).get_config()
config.pop('filters')
config.pop('kernel_initializer')
config.pop('kernel_regularizer')
config.pop('kernel_constraint')
config['depth_multiplier'] = self.depth_multiplier
config['depthwise_initializer'] = initializers.serialize(self.depthwise_initializer)
config['depthwise_regularizer'] = regularizers.serialize(self.depthwise_regularizer)
config['depthwise_constraint'] = constraints.serialize(self.depthwise_constraint)
return config