def sample_variance(self, x, y):
_, _, decoder_lambda, decoder_dense = self.decoder.layers
input1 = K.random_normal(shape=(1000, self.latent_dim))
input2 = K.random_normal(shape=(1000, self.latent_dim))
z = decoder_lambda([input1, input2])
x_decoded_mean = decoder_dense(z)
return K.mean(K.std(x_decoded_mean, axis=0))
def call(self, X):
perturbation = self.sigma_kernel * K.random_normal(
shape=(self.input_dim, self.units), mean=0, stddev=1)
perturbed_kernel = self.kernel + perturbation
output = K.dot(X, perturbed_kernel)
if self.use_bias:
bias_perturbation = self.sigma_bias * K.random_normal(
shape=(self.units, ), mean=0, stddev=1)
perturbed_bias = self.bias + bias_perturbation
output = K.bias_add(output, perturbed_bias)
if self.activation is not None:
output = self.activation(output)
return output
def noised():
stddev = np.sqrt(self.rate / (1.0 - self.rate))
return inputs * K.random_normal(
shape=array_ops.shape(inputs),
mean=1.0,
stddev=stddev,
dtype=inputs.dtype)
def _do_variational_autoencoding(input_signal, latent_dim=2):
x = layers.Conv2D(filters=64,
kernel_size=(3, 3),
strides=2,
padding='same')(input_signal)
x = layers.LeakyReLU()(x)
x = layers.Conv2D(filters=32,
kernel_size=(3, 3),
strides=2,
padding='same')(x)
x = layers.LeakyReLU()(x)
shape_before_flattening = K.int_shape(x)
x = layers.Flatten()(x)
x = layers.Dense(units=32, activation='relu')(x)
z_mean = layers.Dense(units=latent_dim)(x)
z_log_var = layers.Dense(units=latent_dim)(x)
epsilon = K.random_normal(shape=(K.shape(z_mean)[0], latent_dim),
mean=0.,
stddev=1.)
z = z_mean + K.exp(z_log_var) * epsilon
x = layers.Dense(np.prod(shape_before_flattening[1:]),
activation='relu')(z)
x = layers.Reshape(shape_before_flattening[1:])(x)
x = layers.Conv2DTranspose(filters=32,
kernel_size=(3, 3),
strides=2,
padding='same')(x)
x = layers.LeakyReLU()(x)
x = layers.Conv2DTranspose(filters=64,
kernel_size=(3, 3),
strides=2,
padding='same',
activation='relu')(x)
return x
def call(self, x):
if len(x) != 2:
raise Exception('input layers must be a list: mean and stddev')
if len(x[0].shape) != 2 or len(x[1].shape) != 2:
raise Exception(
'input shape is not a vector [batchSize, latentSize]')
mean = x[0]
stddev = x[1]
if self.reg == 'bvae':
# kl divergence:
latent_loss = -0.5 * K.mean(
1 + stddev - K.square(mean) - K.exp(stddev), axis=-1)
# use beta to force less usage of vector space:
# also try to use <capacity> dimensions of the space:
latent_loss = self.beta * K.abs(latent_loss - self.capacity /
self.shape.as_list()[1])
self.add_loss(latent_loss, x)
elif self.reg == 'vae':
# kl divergence:
latent_loss = -0.5 * K.mean(
1 + stddev - K.square(mean) - K.exp(stddev), axis=-1)
self.add_loss(latent_loss, x)
if self.random:
# 'reparameterization trick':
epsilon = K.random_normal(shape=(self.batchSize, self.latentSize),
mean=0.,
stddev=1.)
return mean + K.exp(stddev) * epsilon
else: # do not perform random sampling, simply grab the impulse value
return mean + 0 * stddev # Keras needs the *0 so the gradinent is not None
def sampling(args):
z_mean, z_log_var = args
batch = K.shape(z_mean)[0]
dim = K.int_shape(z_mean)[1]
# by default, random_normal has mean=0 and std=1.0
epsilon = K.random_normal(shape=(batch, dim))
return z_mean + K.exp(0.5 * z_log_var) * epsilon
def _build_latent_vars(self, mu_z, log_var_z, epsilon_std=1., kl_scale=1.):
""" Build keras variables representing the latent space
First, calculate the KL divergence from the input mean and log variance
and add this to the model loss via a KLDivergenceLayer. Then sample an epsilon
and perform a location-scale transformation to obtain the latent embedding, z.
Args:
epsilon_std: standard deviation of p(epsilon)
kl_scale: weight of KL divergence loss
Returns:
Variables representing z and epsilon
"""
# mu_z, log_var_z, kl_batch = KLDivergenceLayer()([mu_z, log_var_z], scale=kl_scale)
lmda_func = lambda inputs: -0.5 * K.sum(1 + inputs[1] - K.square(inputs[0]) - K.exp(inputs[1]), axis=1)
kl_batch = Lambda(lmda_func, name='kl_calc')([mu_z, log_var_z])
kl_batch = Reshape((1,), name='kl_reshape')(kl_batch)
# get standard deviation from log variance:
sigma_z = Lambda(lambda lv: K.exp(0.5 * lv))(log_var_z)
# re-parametrization trick ( z = mu_z + eps * sigma_z)
eps = Input(tensor=K.random_normal(stddev=epsilon_std,
shape=(K.shape(mu_z)[0], self.latentDim_)))
eps_z = Multiply()([sigma_z, eps]) # scale by epsilon sample
z = Add()([mu_z, eps_z])
return z, eps, kl_batch
def _call_one_layer(self, inputs, flatten_memory, training, ws):
dp_mask = self.get_dropout_mask_for_cell(
inputs, training, count=1)
rec_dp_mask = self.get_recurrent_dropout_mask_for_cell(
flatten_memory, training, count=1)
if 0 < self.dropout < 1:
inputs = inputs * dp_mask[0]
if 0 < self.recurrent_dropout < 1:
flatten_memory = flatten_memory * rec_dp_mask[0]
memory = array_ops.reshape(
flatten_memory, shape=[-1, self.num_memory_slots, self.units])
input_gate, forget_gate = self._input_and_forget_gates(inputs, memory, ws)
hs, new_memory = self._attend_over_memory(inputs, memory, ws)
next_memory = input_gate * new_memory + forget_gate * memory
flatten_next_memory = array_ops.reshape(
next_memory, shape=[-1, self.num_memory_slots * self.units])
mus_and_log_sigmas = K.dot(hs, ws["random_kernel"])
mus_and_log_sigmas = K.bias_add(mus_and_log_sigmas, ws["random_bias"])
mus, log_sigmas = array_ops.split(mus_and_log_sigmas, 2, axis=-1)
sigmas = K.log(1.0 + K.exp(log_sigmas + self.sigma_bias))
zs = K.random_normal(shape=K.shape(mus)) * sigmas + mus
return zs, mus, sigmas, hs, flatten_next_memory
def call(self, x):
if len(x) != 2:
raise Exception('input layers must be a list: mean and stddev')
if len(x[0].shape) != 2 or len(x[1].shape) != 2:
raise Exception('input shape is not a vector [batchSize, latentSize]')
mean = x[0]
stddev = x[1]
if self.reg == 'bvae':
# kl divergence:
latent_loss = -0.5 * K.mean(1 + stddev
- K.square(mean)
- K.exp(stddev), axis=-1)
# use beta to force less usage of vector space:
# also try to use <capacity> dimensions of the space:
latent_loss = self.beta * K.abs(latent_loss - self.capacity/self.shape.as_list()[1])
self.add_loss(latent_loss, x)
elif self.reg == 'vae':
# kl divergence:
latent_loss = -0.5 * K.mean(1 + stddev
- K.square(mean)
- K.exp(stddev), axis=-1)
self.add_loss(latent_loss, x)
epsilon = K.random_normal(shape=self.shape,
mean=0., stddev=1.)
if self.random:
# 'reparameterization trick':
return mean + K.exp(stddev) * epsilon
else: # do not perform random sampling, simply grab the impulse value
return mean + 0*stddev # Keras needs the *0 so the gradinent is not None
def sampling(args):
z_mean_, z_log_var_ = args
batch_size = shape(z_mean_)[0]
epsilon = random_normal(shape=(batch_size, latent_size),
mean=0.,
stddev=0.01)
return z_mean_ + exp(z_log_var_ / 2) * epsilon
def sampling(args, batch_size=batch_size, latent_dim=latent_dim, epsilon_std=epsilon_std):
z_mean, z_log_var = args
epsilon = K.random_normal(shape=(batch_size, latent_dim),
mean=0., stddev=epsilon_std)
return z_mean + K.exp(z_log_var) * epsilon
def __init__(self, tensor, by_even_and_odd=False):
if by_even_and_odd:
self.mean, self.logsd = split_channels_by_even_and_odd(tensor)
else:
self.mean, self.logsd = split_channels(tensor)
self.eps = K.random_normal(K.shape(
self.mean)) # eps means like temperature
self.sample = self.mean + K.exp(self.logsd) * self.eps
def call(self, inputs):
if self.factorised:
noise_in = self.scale_noise(
K.random_normal(shape=(self.input_dim.value, )))
noise_out = self.scale_noise(K.random_normal(shape=(self.units, )))
kernel_noise = noise_in[:, None] * noise_out[None, :]
bias_noise = noise_out
else:
kernel_noise = K.random_normal(shape=(self.input_dim.value,
self.units))
bias_noise = K.random_normal(shape=(self.units, ))
out = K.dot(inputs, self.kernel_mu + self.kernel_sigma * kernel_noise)
if self.use_bias:
out = K.bias_add(out,
self.bias_mu + self.bias_sigma * bias_noise,
data_format='channels_last')
if self.activation is not None:
out = self.activation(out)
return out
def sampling(args):
"""Define a sampling for our lambda layer.
Taken from:
https://github.com/keras-team/keras/master/examples/variational_autoencoder.py
"""
z_mean, z_log_var = args
batch = K.shape(z_mean)[0]
dim = K.int_shape(z_mean)[1]
# by default, random_normal has mean=0 and std=1.0
epsilon = K.random_normal(shape=(batch, dim))
return z_mean + K.exp(0.5 * z_log_var) * epsilon
def sampling(self, args):
"""Reparameterization trick by sampling fr an isotropic unit Gaussian.
# Arguments:
args (tensor): mean and log of variance of Q(z|X)
# Returns:
z (tensor): sampled latent vector
"""
z_mean, z_log_var = args
batch = K.shape(z_mean)[0]
dim = K.int_shape(z_mean)[1]
# by default, random_normal has mean=0 and std=1.0
epsilon = K.random_normal(shape=(batch, dim))
return z_mean + K.exp(0.5 * z_log_var) * epsilon
def sampling(args):
"""
# Arguments:
args (tensor): mean and log of variance of Q(z|X)
# Returns:
z (tensor): sampled latent vector
"""
from tensorflow.python.keras import backend as K
z_mean, z_log_var = args
batch = K.shape(z_mean)[0]
dim = K.int_shape(z_mean)[1]
# by default, random_normal has mean=0 and std=1.0
epsilon = K.random_normal(shape=(batch, dim))
return z_mean + K.exp(0.5 * z_log_var) * epsilon
def _call_lstm_core(self, inputs, flatten_memory, training, ws, num_memory_slots=None):
dp_mask = self.get_dropout_mask_for_cell(
inputs, training, count=1)
rec_dp_mask = self.get_recurrent_dropout_mask_for_cell(
flatten_memory, training, count=1)
if 0 < self.dropout < 1:
inputs = inputs * dp_mask[0]
if 0 < self.recurrent_dropout < 1:
flatten_memory = flatten_memory * rec_dp_mask[0]
h_tm1, c_tm1 = array_ops.split(flatten_memory, 2, axis=1)
z = K.dot(inputs, ws['kernel'])
z += K.dot(h_tm1, ws['recurrent_kernel'])
z = K.bias_add(z, ws['bias'])
z = array_ops.split(z, num_or_size_splits=4, axis=1)
z0, z1, z2, z3 = z
z1 += self.forget_bias
i = self.recurrent_activation(z0)
f = self.recurrent_activation(z1)
c = f * c_tm1 + i * self.activation(z2)
o = self.recurrent_activation(z3)
hs = o * self.activation(c)
flatten_next_memory = K.concatenate([hs, c])
mus_and_log_sigmas = K.dot(hs, ws["random_kernel"])
mus_and_log_sigmas = K.bias_add(mus_and_log_sigmas, ws["random_bias"])
mus, log_sigmas = array_ops.split(mus_and_log_sigmas, 2, axis=-1)
sigmas = K.log(1.0 + K.exp(log_sigmas + self.sigma_bias))
zs = K.random_normal(shape=K.shape(mus)) * sigmas + mus
return zs, mus, sigmas, hs, flatten_next_memory
def call(self, inputs):
mean, log_var = inputs
epsilon = K.random_normal(tf.shape(log_var), mean=0., stddev=1.)
sample = epsilon * K.exp(
log_var / 2) + mean # equivalent to e * std + mean
return sample
def sampling(z_mean, z_log_sigma, batch_size, latent_dim):
epsilon = K.random_normal(shape=(batch_size, latent_dim),
mean=0.,
stddev=1.)
return z_mean + K.exp(
z_log_sigma / 2) * epsilon # equivalent to e * std + mean
def sampling(self, args):
z_mean, z_logvar = args
epsilon = K.random_normal(shape=(self.latent_dim, ))
return z_mean + K.exp(z_logvar * 0.5) * epsilon
def sampling(args):
""" Given a normal mean/variance, pull a random sample """
z_mean_, z_log_var_ = args
epsilon = K.random_normal(shape=(BATCH_SIZE, LATENT_DIM), mean=0.)
return z_mean_ + K.exp(z_log_var_ / 2) * epsilon
kl_batch = -.5 * backend.sum(
1 + log_var - backend.square(mu) - backend.exp(log_var), axis=-1)
self.add_loss(backend.mean(kl_batch), inputs=inputs)
return inputs
# Loss Function #
# y_true - True labels #
# y_pred - Predicted labels #
def nll(y_true, y_pred):
return backend.sum(backend.binary_crossentropy(y_true, y_pred), axis=-1)
# Decoder Specific
x = Input(shape=(original_dim, ))
h = Dense(intermediate_dim, activation='relu')(x)
z_mu = Dense(latent_dim)(h)
z_log_var = Dense(latent_dim)(h)
(z_mu, z_log_var) = KLDivergenceLayer()([z_mu, z_log_var])
# Encoder Specific #
z_sigma = Lambda(lambda t: backend.exp(.5 * t))(z_log_var)
eps = Input(tensor=backend.random_normal(
stddev=epsilon_std, shape=(backend.shape(x)[0], latent_dim)))
z_eps = Multiply()([z_sigma, eps])
z = Add()([z_mu, z_eps])
def sampling(arg):
mean = arg[0]
logvar = arg[1]
epsilon = K.random_normal(shape=K.shape(mean), mean=0., stddev=1.)
return mean + K.exp(0.5 * logvar) * epsilon
def sampling(args):
z_mean, z_log_var = args
return K.random_normal(
shape=K.shape(z_log_var), mean=0., stddev=noise_std) * K.exp(
.5 * z_log_var) + z_mean
def sampling(self, args):
self.z_mean, self.z_log_var = args
batch = K.shape(self.z_mean)[0]
dim = K.int_shape(self.z_mean)[1]
epsilon = K.random_normal(shape=(batch, dim))
return self.z_mean + K.exp(0.5 * self.z_log_var) * epsilon
def noised(): return inputs + K.random_normal(shape=array_ops.shape(inputs), mean=0., stddev=stddev)
def sampling(self, args):
z_mean, z_log_var = args
epsilon = K.random_normal(shape=(K.shape(z_mean)[0], self.z_dim),
mean=0.,
stddev=1.)
return (z_mean + K.exp(z_log_var / 2.) * epsilon)
def reparameterization_trick():
epsilon = K.random_normal(shape=logvar.shape, mean=0., stddev=1.)
stddev = K.exp(logvar * 0.5)
return mean + stddev * epsilon
def noised():
eps = K.random_uniform(shape=[1], maxval=self.alpha)
return inputs + K.random_normal(
shape=K.shape(inputs), mean=0., stddev=eps)
def sample_z(self, args):
mu, std = args
eps = K.random_normal(shape=(self.batch_size, self.n_dim), mean=0., stddev=1.)
return mu + K.exp(0.5 * std) * eps
def noised():
return inputs + K.random_normal(shape=array_ops.shape(inputs),
mean=0.,
stddev=self.stddev,
dtype=inputs.dtype)
def noised():
return inputs + K.random_normal(
shape=array_ops.shape(inputs), mean=0., stddev=self.stddev)
def noised():
stddev = np.sqrt(self.rate / (1.0 - self.rate))
return inputs * K.random_normal(
shape=array_ops.shape(inputs), mean=1.0, stddev=stddev)
