def generate_sample(self, configuration: Configuration, metadata: Metadata,
architecture: Architecture,
**additional_inputs: Tensor) -> Tensor:
noise = to_gpu_if_available(
FloatTensor(configuration.batch_size,
architecture.arguments.noise_size).normal_())
architecture.autoencoder.eval()
architecture.generator.eval()
code = architecture.generator(noise, **additional_inputs)
return architecture.autoencoder.decode(code, **additional_inputs)
def train_generator_step(configuration: Configuration, metadata: Metadata,
architecture: Architecture,
batch: Batch) -> float:
# clean previous gradients
architecture.generator_optimizer.zero_grad()
# generate a batch of fake features with the same size as the real feature batch
generated = architecture.generator(batch["features"],
missing_mask=batch["missing_mask"])
# replace the missing features by the generated
imputed = compose_with_mask(
mask=batch["missing_mask"],
differentiable=True, # now there are no NaNs and this should be used
where_one=generated,
where_zero=batch["raw_features"])
# generate hint
hint = generate_hint(batch["missing_mask"],
configuration.hint_probability, metadata)
# calculate loss
loss = architecture.generator_loss(architecture=architecture,
features=batch["raw_features"],
generated=generated,
imputed=imputed,
hint=hint,
non_missing_mask=inverse_mask(
batch["missing_mask"]))
# calculate gradients
loss.backward()
# update the generator weights
architecture.generator_optimizer.step()
# return the loss
return to_cpu_if_was_in_gpu(loss).item()
def impute(self, configuration: Configuration, metadata: Metadata,
architecture: Architecture, batch: Dict[str, Tensor]) -> Tensor:
return architecture.generator(batch["features"],
missing_mask=batch["missing_mask"])
def sample_fake(self, architecture: Architecture, size: int, **additional_inputs: Tensor) -> Tensor:
# for now the noise comes from a normal distribution but could be other distribution
noise = to_gpu_if_available(FloatTensor(size, architecture.arguments.noise_size).normal_())
return architecture.generator(noise, **additional_inputs)
def impute(self, configuration: Configuration, metadata: Metadata,
architecture: Architecture, batch: Dict[str, Tensor]) -> Tensor:
# loss function
loss_function = create_component(architecture, metadata,
configuration.reconstruction_loss)
masked_loss_function = MaskedReconstructionLoss(loss_function)
batch_size = batch["features"].shape[0] * batch["features"].shape[1]
# we need the non missing mask for the loss
non_missing_mask = inverse_mask(batch["missing_mask"])
# initial noise
noise = to_gpu_if_available(
FloatTensor(len(batch["features"]),
architecture.arguments.noise_size).normal_())
noise.requires_grad_()
# it is not the generator what we are updating
# it is the noise
optimizer = Adam([noise],
weight_decay=0,
lr=configuration.noise_learning_rate)
architecture.generator.eval()
# logger
log_path = create_parent_directories_if_needed(configuration.logs)
logger = TrainLogger(self.logger, log_path, False)
# initial generation
logger.start_timer()
generated = architecture.generator(noise,
condition=batch.get("labels"))
# iterate until we reach the maximum number of iterations or until the non missing loss is too small
max_iterations = configuration.max_iterations
for iteration in range(1, max_iterations + 1):
# compute the loss on the non-missing values
non_missing_loss = masked_loss_function(generated,
batch["features"],
non_missing_mask)
logger.log(iteration, max_iterations, "non_missing_loss",
to_cpu_if_was_in_gpu(non_missing_loss).item())
# this loss only makes sense if the ground truth is present
# only used for debugging
if configuration.get("log_missing_loss", False):
# this part should not affect the gradient calculation
with torch.no_grad():
missing_loss = masked_loss_function(
generated, batch["raw_features"],
batch["missing_mask"])
logger.log(iteration, max_iterations, "missing_loss",
to_cpu_if_was_in_gpu(missing_loss).item())
loss = loss_function(generated,
batch["raw_features"]) / batch_size
logger.log(iteration, max_iterations, "loss",
to_cpu_if_was_in_gpu(loss).item())
# if the generation is good enough we stop
if to_cpu_if_was_in_gpu(non_missing_loss).item(
) < configuration.get("tolerance", 1e-5):
break
# clear previous gradients
optimizer.zero_grad()
# compute the gradients
non_missing_loss.backward()
# update the noise
optimizer.step()
# generate next
logger.start_timer()
generated = architecture.generator(noise,
condition=batch.get("labels"))
return generated
def val_batch(architecture: Architecture, batch: Batch,
post_processing: PostProcessing) -> float:
generated = architecture.generator(batch["features"],
missing_mask=batch["missing_mask"])
loss = architecture.val_loss(post_processing, generated, batch)
return to_cpu_if_was_in_gpu(loss).item()