def rank1_resnet_layer(inputs, filters, kernel_size, strides, activation,
alpha_initializer, gamma_initializer, alpha_regularizer,
gamma_regularizer, use_additive_perturbation,
ensemble_size, random_sign_init, dropout_rate):
"""Bayesian rank-1 2D Convolution-Batch Norm-Activation stack builder.
Args:
inputs: tf.Tensor.
filters: Number of filters for Conv2D.
kernel_size: Kernel dimensions for Conv2D.
strides: Stride dimensinons for Conv2D.
activation: tf.keras.activations.Activation.
alpha_initializer: The initializer for the alpha parameters.
gamma_initializer: The initializer for the gamma parameters.
alpha_regularizer: The regularizer for the alpha parameters.
gamma_regularizer: The regularizer for the gamma parameters.
use_additive_perturbation: Whether or not to use additive perturbations
instead of multiplicative perturbations.
ensemble_size: Number of ensemble members.
random_sign_init: Value used to initialize trainable deterministic
initializers, as applicable. Values greater than zero result in
initialization to a random sign vector, where random_sign_init is the
probability of a 1 value. Values less than zero result in initialization
from a Gaussian with mean 1 and standard deviation equal to
-random_sign_init.
dropout_rate: Dropout rate.
Returns:
tf.Tensor.
"""
x = inputs
x = ed.layers.Conv2DRank1(
filters,
kernel_size=kernel_size,
strides=strides,
padding='same',
use_bias=False,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
kernel_initializer='he_normal',
alpha_regularizer=alpha_regularizer,
gamma_regularizer=gamma_regularizer,
use_additive_perturbation=use_additive_perturbation,
ensemble_size=ensemble_size)(x)
x = tf.keras.layers.BatchNormalization(epsilon=BATCH_NORM_EPSILON,
momentum=BATCH_NORM_DECAY)(x)
if activation is not None:
x = tf.keras.layers.Activation(activation)(x)
return x
def rank1_resnet_v1(input_shape, depth, num_classes, width_multiplier,
alpha_initializer, gamma_initializer, alpha_regularizer,
gamma_regularizer, use_additive_perturbation,
ensemble_size, random_sign_init, dropout_rate):
"""Builds Bayesian rank-1 prior ResNet v1.
Args:
input_shape: tf.Tensor.
depth: ResNet depth.
num_classes: Number of output classes.
width_multiplier: Integer to multiply the number of typical filters by.
alpha_initializer: The initializer for the alpha parameters.
gamma_initializer: The initializer for the gamma parameters.
alpha_regularizer: The regularizer for the alpha parameters.
gamma_regularizer: The regularizer for the gamma parameters.
use_additive_perturbation: Whether or not to use additive perturbations
instead of multiplicative perturbations.
ensemble_size: Number of ensemble members.
random_sign_init: Value used to initialize trainable deterministic
initializers, as applicable. Values greater than zero result in
initialization to a random sign vector, where random_sign_init is the
probability of a 1 value. Values less than zero result in initialization
from a Gaussian with mean 1 and standard deviation equal to
-random_sign_init.
dropout_rate: Dropout rate.
Returns:
tf.keras.Model.
"""
if (depth - 2) % 6 != 0:
raise ValueError('depth should be 6n+2 (e.g., 20, 32, 44).')
filters = 16 * width_multiplier
num_res_blocks = int((depth - 2) / 6)
resnet_layer = functools.partial(
rank1_resnet_layer,
alpha_initializer=alpha_initializer,
gamma_initializer=gamma_initializer,
alpha_regularizer=alpha_regularizer,
gamma_regularizer=gamma_regularizer,
use_additive_perturbation=use_additive_perturbation,
ensemble_size=ensemble_size,
random_sign_init=random_sign_init,
dropout_rate=dropout_rate)
inputs = tf.keras.layers.Input(shape=input_shape)
x = resnet_layer(inputs,
filters=filters,
kernel_size=3,
strides=1,
activation='relu')
for stack in range(3):
for res_block in range(num_res_blocks):
strides = 1
if stack > 0 and res_block == 0: # first layer but not first stack
strides = 2 # downsample
y = resnet_layer(x,
filters=filters,
kernel_size=3,
strides=strides,
activation='relu')
y = resnet_layer(y,
filters=filters,
kernel_size=3,
strides=1,
activation=None)
if stack > 0 and res_block == 0: # first layer but not first stack
# linear projection residual shortcut connection to match
# changed dims
x = resnet_layer(x,
filters=filters,
kernel_size=1,
strides=strides,
activation=None)
x = tf.keras.layers.add([x, y])
x = tf.keras.layers.Activation('relu')(x)
filters *= 2
# v1 does not use BN after last shortcut connection-ReLU
x = tf.keras.layers.AveragePooling2D(pool_size=8)(x)
x = tf.keras.layers.Flatten()(x)
x = ed.layers.DenseRank1(
num_classes,
activation=None,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
kernel_initializer='he_normal',
alpha_regularizer=alpha_regularizer,
gamma_regularizer=gamma_regularizer,
use_additive_perturbation=use_additive_perturbation,
ensemble_size=ensemble_size)(x)
model = tf.keras.Model(inputs=inputs, outputs=x)
return model
def basic_block(inputs, filters, strides, alpha_initializer, gamma_initializer,
alpha_regularizer, gamma_regularizer,
use_additive_perturbation, ensemble_size, random_sign_init,
dropout_rate, prior_mean, prior_stddev):
"""Basic residual block of two 3x3 convs.
Args:
inputs: tf.Tensor.
filters: Number of filters for Conv2D.
strides: Stride dimensions for Conv2D.
alpha_initializer: The initializer for the alpha parameters.
gamma_initializer: The initializer for the gamma parameters.
alpha_regularizer: The regularizer for the alpha parameters.
gamma_regularizer: The regularizer for the gamma parameters.
use_additive_perturbation: Whether or not to use additive perturbations
instead of multiplicative perturbations.
ensemble_size: Number of ensemble members.
random_sign_init: Value used to initialize trainable deterministic
initializers, as applicable. Values greater than zero result in
initialization to a random sign vector, where random_sign_init is the
probability of a 1 value. Values less than zero result in initialization
from a Gaussian with mean 1 and standard deviation equal to
-random_sign_init.
dropout_rate: Dropout rate.
prior_mean: Mean of the prior.
prior_stddev: Standard deviation of the prior.
Returns:
tf.Tensor.
"""
x = inputs
y = inputs
y = BatchNormalization()(y)
y = tf.keras.layers.Activation('relu')(y)
y = Conv2DRank1(
filters,
strides=strides,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
alpha_regularizer=utils.make_regularizer(alpha_regularizer, prior_mean,
prior_stddev),
gamma_regularizer=utils.make_regularizer(gamma_regularizer, prior_mean,
prior_stddev),
use_additive_perturbation=use_additive_perturbation,
ensemble_size=ensemble_size)(y)
y = BatchNormalization()(y)
y = tf.keras.layers.Activation('relu')(y)
y = Conv2DRank1(
filters,
strides=1,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
alpha_regularizer=utils.make_regularizer(alpha_regularizer, prior_mean,
prior_stddev),
gamma_regularizer=utils.make_regularizer(gamma_regularizer, prior_mean,
prior_stddev),
use_additive_perturbation=use_additive_perturbation,
ensemble_size=ensemble_size)(y)
if not x.shape.is_compatible_with(y.shape):
x = Conv2DRank1(
filters,
kernel_size=1,
strides=strides,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
alpha_regularizer=utils.make_regularizer(alpha_regularizer,
prior_mean, prior_stddev),
gamma_regularizer=utils.make_regularizer(gamma_regularizer,
prior_mean, prior_stddev),
use_additive_perturbation=use_additive_perturbation,
ensemble_size=ensemble_size)(x)
x = tf.keras.layers.add([x, y])
return x
def wide_resnet(input_shape, depth, width_multiplier, num_classes,
alpha_initializer, gamma_initializer, alpha_regularizer,
gamma_regularizer, use_additive_perturbation, ensemble_size,
random_sign_init, dropout_rate, prior_mean, prior_stddev):
"""Builds Wide ResNet.
Following Zagoruyko and Komodakis (2016), it accepts a width multiplier on the
number of filters. Using three groups of residual blocks, the network maps
spatial features of size 32x32 -> 16x16 -> 8x8.
Args:
input_shape: tf.Tensor.
depth: Total number of convolutional layers. "n" in WRN-n-k. It differs from
He et al. (2015)'s notation which uses the maximum depth of the network
counting non-conv layers like dense.
width_multiplier: Integer to multiply the number of typical filters by. "k"
in WRN-n-k.
num_classes: Number of output classes.
alpha_initializer: The initializer for the alpha parameters.
gamma_initializer: The initializer for the gamma parameters.
alpha_regularizer: The regularizer for the alpha parameters.
gamma_regularizer: The regularizer for the gamma parameters.
use_additive_perturbation: Whether or not to use additive perturbations
instead of multiplicative perturbations.
ensemble_size: Number of ensemble members.
random_sign_init: Value used to initialize trainable deterministic
initializers, as applicable. Values greater than zero result in
initialization to a random sign vector, where random_sign_init is the
probability of a 1 value. Values less than zero result in initialization
from a Gaussian with mean 1 and standard deviation equal to
-random_sign_init.
dropout_rate: Dropout rate.
prior_mean: Mean of the prior.
prior_stddev: Standard deviation of the prior.
Returns:
tf.keras.Model.
"""
if (depth - 4) % 6 != 0:
raise ValueError('depth should be 6n+4 (e.g., 16, 22, 28, 40).')
num_blocks = (depth - 4) // 6
inputs = tf.keras.layers.Input(shape=input_shape)
x = Conv2DRank1(
16,
strides=1,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
alpha_regularizer=utils.make_regularizer(alpha_regularizer, prior_mean,
prior_stddev),
gamma_regularizer=utils.make_regularizer(gamma_regularizer, prior_mean,
prior_stddev),
use_additive_perturbation=use_additive_perturbation,
ensemble_size=ensemble_size)(inputs)
for strides, filters in zip([1, 2, 2], [16, 32, 64]):
x = group(x,
filters=filters * width_multiplier,
strides=strides,
num_blocks=num_blocks,
alpha_initializer=alpha_initializer,
gamma_initializer=gamma_initializer,
alpha_regularizer=alpha_regularizer,
gamma_regularizer=gamma_regularizer,
use_additive_perturbation=use_additive_perturbation,
ensemble_size=ensemble_size,
random_sign_init=random_sign_init,
dropout_rate=dropout_rate,
prior_mean=prior_mean,
prior_stddev=prior_stddev)
x = BatchNormalization()(x)
x = tf.keras.layers.Activation('relu')(x)
x = tf.keras.layers.AveragePooling2D(pool_size=8)(x)
x = tf.keras.layers.Flatten()(x)
x = rank1_bnn_layers.DenseRank1(
num_classes,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
kernel_initializer='he_normal',
activation=None,
alpha_regularizer=utils.make_regularizer(alpha_regularizer, prior_mean,
prior_stddev),
gamma_regularizer=utils.make_regularizer(gamma_regularizer, prior_mean,
prior_stddev),
use_additive_perturbation=use_additive_perturbation,
ensemble_size=ensemble_size)(x)
return tf.keras.Model(inputs=inputs, outputs=x)
def bottleneck_block(inputs, filters, stage, block, strides, alpha_initializer,
gamma_initializer, alpha_regularizer, gamma_regularizer,
use_additive_perturbation, ensemble_size,
random_sign_init, dropout_rate, prior_stddev, use_tpu):
"""Residual block with 1x1 -> 3x3 -> 1x1 convs in main path.
Note that strides appear in the second conv (3x3) rather than the first (1x1).
This is also known as "ResNet v1.5" as it differs from He et al. (2015)
(http://torch.ch/blog/2016/02/04/resnets.html).
Args:
inputs: tf.Tensor.
filters: list of integers, the filters of 3 conv layer at main path
stage: integer, current stage label, used for generating layer names
block: 'a','b'..., current block label, used for generating layer names
strides: Strides for the second conv layer in the block.
alpha_initializer: The initializer for the alpha parameters.
gamma_initializer: The initializer for the gamma parameters.
alpha_regularizer: The regularizer for the alpha parameters.
gamma_regularizer: The regularizer for the gamma parameters.
use_additive_perturbation: Whether or not to use additive perturbations
instead of multiplicative perturbations.
ensemble_size: Number of ensemble members.
random_sign_init: Value used to initialize trainable deterministic
initializers, as applicable. Values greater than zero result in
initialization to a random sign vector, where random_sign_init is the
probability of a 1 value. Values less than zero result in initialization
from a Gaussian with mean 1 and standard deviation equal to
-random_sign_init.
dropout_rate: Dropout rate.
prior_stddev: Standard deviation of the prior.
use_tpu: whether the model runs on TPU.
Returns:
tf.Tensor.
"""
filters1, filters2, filters3 = filters
conv_name_base = 'res' + str(stage) + block + '_branch'
bn_name_base = 'bn' + str(stage) + block + '_branch'
x = rank1_bnn_layers.Conv2DRank1(
filters1,
kernel_size=1,
use_bias=False,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
kernel_initializer='he_normal',
alpha_regularizer=utils.make_regularizer(alpha_regularizer, 1.,
prior_stddev),
gamma_regularizer=utils.make_regularizer(gamma_regularizer, 1.,
prior_stddev),
use_additive_perturbation=use_additive_perturbation,
name=conv_name_base + '2a',
ensemble_size=ensemble_size)(inputs)
x = ed.layers.ensemble_batchnorm(x,
ensemble_size=ensemble_size,
use_tpu=use_tpu,
momentum=BATCH_NORM_DECAY,
epsilon=BATCH_NORM_EPSILON,
name=bn_name_base + '2a')
x = tf.keras.layers.Activation('relu')(x)
x = rank1_bnn_layers.Conv2DRank1(
filters2,
kernel_size=3,
strides=strides,
padding='same',
use_bias=False,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
kernel_initializer='he_normal',
alpha_regularizer=utils.make_regularizer(alpha_regularizer, 1.,
prior_stddev),
gamma_regularizer=utils.make_regularizer(gamma_regularizer, 1.,
prior_stddev),
use_additive_perturbation=use_additive_perturbation,
name=conv_name_base + '2b',
ensemble_size=ensemble_size)(x)
x = ed.layers.ensemble_batchnorm(x,
ensemble_size=ensemble_size,
use_tpu=use_tpu,
momentum=BATCH_NORM_DECAY,
epsilon=BATCH_NORM_EPSILON,
name=bn_name_base + '2b')
x = tf.keras.layers.Activation('relu')(x)
x = rank1_bnn_layers.Conv2DRank1(
filters3,
kernel_size=1,
use_bias=False,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
kernel_initializer='he_normal',
alpha_regularizer=utils.make_regularizer(alpha_regularizer, 1.,
prior_stddev),
gamma_regularizer=utils.make_regularizer(gamma_regularizer, 1.,
prior_stddev),
use_additive_perturbation=use_additive_perturbation,
name=conv_name_base + '2c',
ensemble_size=ensemble_size)(x)
x = ed.layers.ensemble_batchnorm(x,
ensemble_size=ensemble_size,
use_tpu=use_tpu,
momentum=BATCH_NORM_DECAY,
epsilon=BATCH_NORM_EPSILON,
name=bn_name_base + '2c')
shortcut = inputs
if not x.shape.is_compatible_with(shortcut.shape):
shortcut = rank1_bnn_layers.Conv2DRank1(
filters3,
kernel_size=1,
strides=strides,
use_bias=False,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
kernel_initializer='he_normal',
alpha_regularizer=utils.make_regularizer(alpha_regularizer, 1.,
prior_stddev),
gamma_regularizer=utils.make_regularizer(gamma_regularizer, 1.,
prior_stddev),
use_additive_perturbation=use_additive_perturbation,
name=conv_name_base + '1',
ensemble_size=ensemble_size)(inputs)
shortcut = ed.layers.ensemble_batchnorm(shortcut,
ensemble_size=ensemble_size,
use_tpu=use_tpu,
momentum=BATCH_NORM_DECAY,
epsilon=BATCH_NORM_EPSILON,
name=bn_name_base + '1')
x = tf.keras.layers.add([x, shortcut])
x = tf.keras.layers.Activation('relu')(x)
return x
def rank1_resnet50(input_shape, num_classes, alpha_initializer,
gamma_initializer, alpha_regularizer, gamma_regularizer,
use_additive_perturbation, ensemble_size, random_sign_init,
dropout_rate, prior_stddev, use_tpu):
"""Builds ResNet50 with rank 1 priors.
Using strided conv, pooling, four groups of residual blocks, and pooling, the
network maps spatial features of size 224x224 -> 112x112 -> 56x56 -> 28x28 ->
14x14 -> 7x7 (Table 1 of He et al. (2015)).
Args:
input_shape: Shape tuple of input excluding batch dimension.
num_classes: Number of output classes.
alpha_initializer: The initializer for the alpha parameters.
gamma_initializer: The initializer for the gamma parameters.
alpha_regularizer: The regularizer for the alpha parameters.
gamma_regularizer: The regularizer for the gamma parameters.
use_additive_perturbation: Whether or not to use additive perturbations
instead of multiplicative perturbations.
ensemble_size: Number of ensemble members.
random_sign_init: Value used to initialize trainable deterministic
initializers, as applicable. Values greater than zero result in
initialization to a random sign vector, where random_sign_init is the
probability of a 1 value. Values less than zero result in initialization
from a Gaussian with mean 1 and standard deviation equal to
-random_sign_init.
dropout_rate: Dropout rate.
prior_stddev: Standard deviation of the prior.
use_tpu: whether the model runs on TPU.
Returns:
tf.keras.Model.
"""
group_ = functools.partial(
group,
alpha_initializer=alpha_initializer,
gamma_initializer=gamma_initializer,
alpha_regularizer=alpha_regularizer,
gamma_regularizer=gamma_regularizer,
use_additive_perturbation=use_additive_perturbation,
ensemble_size=ensemble_size,
random_sign_init=random_sign_init,
dropout_rate=dropout_rate,
prior_stddev=prior_stddev,
use_tpu=use_tpu)
inputs = tf.keras.layers.Input(shape=input_shape)
x = tf.keras.layers.ZeroPadding2D(padding=3, name='conv1_pad')(inputs)
x = rank1_bnn_layers.Conv2DRank1(
64,
kernel_size=7,
strides=2,
padding='valid',
use_bias=False,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
kernel_initializer='he_normal',
alpha_regularizer=utils.make_regularizer(alpha_regularizer, 1.,
prior_stddev),
gamma_regularizer=utils.make_regularizer(gamma_regularizer, 1.,
prior_stddev),
use_additive_perturbation=use_additive_perturbation,
name='conv1',
ensemble_size=ensemble_size)(x)
x = ed.layers.ensemble_batchnorm(x,
ensemble_size=ensemble_size,
use_tpu=use_tpu,
momentum=BATCH_NORM_DECAY,
epsilon=BATCH_NORM_EPSILON,
name='bn_conv1')
x = tf.keras.layers.Activation('relu')(x)
x = tf.keras.layers.MaxPooling2D(3, strides=(2, 2), padding='same')(x)
x = group_(x, [64, 64, 256], stage=2, num_blocks=3, strides=1)
x = group_(x, [128, 128, 512], stage=3, num_blocks=4, strides=2)
x = group_(x, [256, 256, 1024], stage=4, num_blocks=6, strides=2)
x = group_(x, [512, 512, 2048], stage=5, num_blocks=3, strides=2)
x = tf.keras.layers.GlobalAveragePooling2D(name='avg_pool')(x)
x = rank1_bnn_layers.DenseRank1(
num_classes,
alpha_initializer=utils.make_initializer(alpha_initializer,
random_sign_init,
dropout_rate),
gamma_initializer=utils.make_initializer(gamma_initializer,
random_sign_init,
dropout_rate),
kernel_initializer=tf.keras.initializers.RandomNormal(stddev=0.01),
alpha_regularizer=utils.make_regularizer(alpha_regularizer, 1.,
prior_stddev),
gamma_regularizer=utils.make_regularizer(gamma_regularizer, 1.,
prior_stddev),
use_additive_perturbation=use_additive_perturbation,
ensemble_size=ensemble_size,
activation=None,
name='fc1000')(x)
return tf.keras.Model(inputs=inputs, outputs=x, name='resnet50')
