def test_on_batch(model,
inputs,
targets,
sample_weights=None,
output_loss_metrics=None):
"""Calculates the loss for one input batch.
Args:
model: Model whose loss has to be calculated.
inputs: Input batch data.
targets: Target batch data.
sample_weights: Sample weight batch data.
output_loss_metrics: List of metrics that are used to aggregated output
loss values.
Returns:
Dict with three items:
'total_loss': single tensor for overall loss,
'output_losses': list of tensors for loss corresponding to each of the
model output. Could be a empty list when model has only one output.
'metrics': list of tensors for metric specified.
"""
inputs = training_utils_v1.cast_to_model_input_dtypes(inputs, model)
with backend.eager_learning_phase_scope(0):
outs, total_loss, output_losses, masks = _model_loss(
model,
inputs,
targets,
sample_weights=sample_weights,
training=False,
output_loss_metrics=output_loss_metrics,
)
if not isinstance(outs, list):
outs = [outs]
metrics_results = _eager_metrics_fn(model,
outs,
targets,
sample_weights=sample_weights,
masks=masks)
total_loss = tf.nest.flatten(total_loss)
return {
"total_loss": total_loss,
"output_losses": output_losses,
"metrics": metrics_results,
}
def _process_single_batch(model,
inputs,
targets,
output_loss_metrics=None,
sample_weights=None,
training=False):
"""Calculate the loss and gradient for one input batch.
The model weights are updated if training is set to True.
Arguments:
model: Model whose loss has to be calculated.
inputs: List of input arrays.
targets: List of target arrays.
output_loss_metrics: List of metrics that are used to aggregated output
loss values.
sample_weights: Optional list of sample weight arrays.
training: The boolean represents if the weights of the model are updated.
'fit' methods will set this to True while 'evaluate' methods will
set this to False.
Returns:
output of the model, total loss, the loss and the mask
associated with each output.
Raises:
ValueError: If the model has no loss to optimize.
"""
with backend.eager_learning_phase_scope(1 if training else 0), \
training_utils.RespectCompiledTrainableState(model):
with GradientTape() as tape:
outs, total_loss, output_losses, masks = (_model_loss(
model,
inputs,
targets,
output_loss_metrics=output_loss_metrics,
sample_weights=sample_weights,
training=training))
if isinstance(model.optimizer,
loss_scale_optimizer.LossScaleOptimizer):
scaled_total_loss = model.optimizer.get_scaled_loss(total_loss)
else:
scaled_total_loss = total_loss
if training:
trainable_weights = model.trainable_weights
if trainable_weights:
# TODO(tanzheny) b/132690565: Provide mechanism for user to override
# model.train_on_batch.
if hasattr(model, '_backwards'):
model._backwards(tape, scaled_total_loss)
else:
grads = tape.gradient(scaled_total_loss, trainable_weights)
if isinstance(model.optimizer,
loss_scale_optimizer.LossScaleOptimizer):
grads = model.optimizer.get_unscaled_gradients(grads)
model.optimizer.apply_gradients(
zip(grads, trainable_weights))
else:
logging.warning(
'The list of trainable weights is empty. Make sure that'
' you are not setting model.trainable to False before '
'compiling the model.')
return outs, total_loss, output_losses, masks
def model_iteration(model,
data,
steps_per_epoch=None,
epochs=1,
verbose=1,
callbacks=None,
validation_data=None,
validation_steps=None,
validation_freq=1,
class_weight=None,
max_queue_size=10,
workers=1,
use_multiprocessing=False,
shuffle=False,
initial_epoch=0,
mode=ModeKeys.TRAIN,
batch_size=None,
steps_name='steps',
**kwargs):
"""Loop function for arrays of data with modes TRAIN/TEST/PREDICT.
Arguments:
model: Keras Model instance.
data: Either a tuple of NumPy/Tensor inputs (i.e. `(x,)` or `(x, y)` or
`(x, y, sample_weights)`) or a generator or
`keras.utils.data_utils.Sequence` object or Eager Iterator or Dataset.
steps_per_epoch: Total number of steps (batches of samples) before
declaring one epoch finished and starting the next epoch. Ignored with
the default value of `None`.
epochs: Number of times to iterate over the data.
verbose: 0, 1, or 2. Verbosity mode.
0 = silent, 1 = progress bar, 2 = one line per epoch.
Note that the progress bar is not particularly useful when
logged to a file, so verbose=2 is recommended when not running
interactively (eg, in a production environment).
callbacks: List of callbacks to be called during training.
validation_data: Either a tuple of NumPy/Tensor inputs (i.e. `(x,)` or
`(x, y)` or `(x, y, sample_weights)`) or a generator or
`keras.utils.data_utils.Sequence` object or Eager Iterator or Dataset.
validation_steps: Total number of steps (batches of samples) before
declaring validation finished.
validation_freq: Only relevant if validation data is provided. Integer or
`collections.abc.Container` instance (e.g. list, tuple, etc.). If an
integer, specifies how many training epochs to run before a new
validation run is performed, e.g. `validation_freq=2` runs
validation every 2 epochs. If a Container, specifies the epochs on
which to run validation, e.g. `validation_freq=[1, 2, 10]` runs
validation at the end of the 1st, 2nd, and 10th epochs.
class_weight: Dictionary mapping class indices to a weight for the class.
max_queue_size: Integer. Maximum size for the generator queue. If
unspecified, `max_queue_size` will default to 10.
workers: Integer. Maximum number of processes to spin up when using
process-based threading. If unspecified, `workers` will default to 1. If
0, will execute the generator on the main thread.
use_multiprocessing: Boolean. If `True`, use process-based threading. If
unspecified, `use_multiprocessing` will default to `False`. Note that
because this implementation relies on multiprocessing, you should not
pass non-picklable arguments to the generator as they can't be passed
easily to children processes.
shuffle: Boolean. Whether to shuffle the order of the batches at the
beginning of each epoch. Only used with instances of `Sequence`
(`keras.utils.Sequence`). Has no effect when `steps_per_epoch` is not
`None`.
initial_epoch: Epoch at which to start training (useful for resuming a
previous training run).
mode: One of ModeKeys.TRAIN/ModeKeys.TEST/ModeKeys.PREDICT.
batch_size: Integer batch size or None if unknown. Will only be used if
`data` is in NumPy/Tensor format.
steps_name: The string name of the steps argument, either `steps`,
`validation_steps`, or `steps_per_epoch`. Only used for error message
formatting.
**kwargs: Additional arguments for backwards compatibility. `steps` is
accepted as an alias for `steps_per_epoch`.
Returns:
- In TRAIN mode: `History` object.
- In TEST mode: Evaluation metrics.
- In PREDICT mode: Outputs of the Model called on inputs.
Raises:
ValueError: in case of invalid arguments.
"""
if 'steps' in kwargs:
steps_per_epoch = kwargs['steps']
# Determine the number of steps per epoch and whether we should reset the
# dataset at the end of each epoch.
reset_dataset_after_each_epoch = False
original_dataset = None
is_dataset = isinstance(data, (tf.data.Dataset, tf.compat.v1.data.Dataset))
if is_dataset:
original_dataset = data
if steps_per_epoch is None:
reset_dataset_after_each_epoch = True
steps_per_epoch = training_utils_v1.infer_steps_for_dataset(
model,
data,
steps_per_epoch,
epochs=epochs,
steps_name=steps_name)
# Convert to a format that supports `next(generator)`.
generator, steps_per_epoch = convert_to_generator_like(
data,
steps_per_epoch=steps_per_epoch,
batch_size=batch_size,
epochs=epochs - initial_epoch,
shuffle=shuffle)
do_validation = validation_data is not None
is_sequence = isinstance(generator, data_utils.Sequence)
_validate_arguments(is_sequence, is_dataset, use_multiprocessing, workers,
steps_per_epoch, validation_data, validation_steps,
mode, kwargs)
batch_function = _make_execution_function(model,
mode,
class_weight=class_weight)
# Create the queue for the generator.
enqueuer = None
if not is_dataset:
generator, enqueuer = _make_enqueued_generator(
generator,
workers=workers,
use_multiprocessing=use_multiprocessing,
max_queue_size=max_queue_size,
shuffle=shuffle)
num_samples_or_steps, use_steps = _get_num_samples_or_steps(
data, steps_per_epoch)
count_mode = 'steps' if use_steps else 'samples'
callbacks = cbks.configure_callbacks(callbacks,
model,
do_validation=do_validation,
epochs=epochs,
steps_per_epoch=steps_per_epoch,
batch_size=batch_size,
samples=num_samples_or_steps,
count_mode=count_mode,
verbose=verbose,
mode=mode)
if mode == ModeKeys.PREDICT:
aggregator = training_utils_v1.OutputsAggregator(True,
steps=steps_per_epoch)
else:
aggregator = training_utils_v1.MetricsAggregator(True,
steps=steps_per_epoch)
should_set_learning_phase = tf.executing_eagerly() and model.run_eagerly
if should_set_learning_phase:
learning_phase_scope = backend.eager_learning_phase_scope(
1 if mode == ModeKeys.TRAIN else 0)
learning_phase_scope.__enter__()
callbacks.model.stop_training = False
callbacks._call_begin_hook(mode)
initial_epoch = model._maybe_load_initial_epoch_from_ckpt(
initial_epoch, mode)
for epoch in range(initial_epoch, epochs):
if callbacks.model.stop_training:
break
# Setup work for each epoch.
model.reset_metrics()
epoch_logs = {}
if mode == ModeKeys.TRAIN:
callbacks.on_epoch_begin(epoch, epoch_logs)
if steps_per_epoch is None:
# Loop over dataset until `OutOfRangeError` is raised.
target_steps = np.inf
else:
# Loop over dataset for the specified number of steps.
target_steps = steps_per_epoch
step = 0
while step < target_steps:
batch_data = _get_next_batch(generator)
if batch_data is None:
if is_dataset:
# The dataset passed by the user ran out of batches.
# Now we know the cardinality of the dataset.
# If steps_per_epoch was specified, then running out of data is
# unexpected, so we stop training and inform the user.
if steps_per_epoch:
callbacks.model.stop_training = True
logging.warning(
'Your dataset ran out of data; interrupting training. '
'Make sure that your dataset can generate at least '
'`%s * epochs` batches (in this case, %d batches). '
'You may need to use the repeat() function when '
'building your dataset.' %
(steps_name, steps_per_epoch * epochs))
elif step > 0:
steps_per_epoch = step
aggregator.steps = steps_per_epoch
else:
# We ran out of batches while the user passed an iterator (legacy).
callbacks.model.stop_training = True
logging.warning(
'Your dataset iterator ran out of data; '
'interrupting training. Make sure that your iterator '
'can generate at least `%s * epochs` '
'batches (in this case, %d batches). You may need to'
'use the repeat() function when building your '
'dataset.' % (steps_name, steps_per_epoch * epochs))
break
# `batch_size` used for validation data if validation
# data is NumPy/EagerTensors.
batch_size = int(tf.nest.flatten(batch_data)[0].shape[0])
# Callbacks batch begin.
batch_logs = {'batch': step, 'size': batch_size}
callbacks._call_batch_hook(mode, 'begin', step, batch_logs)
is_deferred = not model._is_compiled
batch_outs = batch_function(*batch_data)
if not isinstance(batch_outs, list):
batch_outs = [batch_outs]
if step == 0:
aggregator.create(batch_outs)
if is_deferred:
# Set callbacks params. We do this here when model is compiled only
# in the first iteration of this loop (deferred build scenario).
cbks.set_callback_parameters(
callbacks,
model,
do_validation=do_validation,
batch_size=batch_size,
epochs=epochs,
steps_per_epoch=steps_per_epoch,
samples=num_samples_or_steps,
verbose=verbose,
mode=mode)
# Aggregate results.
aggregator.aggregate(batch_outs)
# Callbacks batch end.
batch_logs = cbks.make_logs(model, batch_logs, batch_outs, mode)
callbacks._call_batch_hook(mode, 'end', step, batch_logs)
step += 1
if callbacks.model.stop_training:
break
aggregator.finalize()
results = aggregator.results
epoch_logs = cbks.make_logs(model, epoch_logs, results, mode)
if len(results) == 1:
results = results[0]
# Run the test loop every epoch during training.
if (do_validation and training_utils_v1.should_run_validation(
validation_freq, epoch) and not callbacks.model.stop_training):
val_results = model_iteration(
model,
validation_data,
steps_per_epoch=validation_steps,
batch_size=batch_size,
class_weight=class_weight,
workers=workers,
use_multiprocessing=use_multiprocessing,
max_queue_size=max_queue_size,
callbacks=callbacks,
verbose=verbose,
mode=ModeKeys.TEST,
steps_name='validation_steps')
if not isinstance(val_results, list):
val_results = [val_results]
epoch_logs = cbks.make_logs(model,
epoch_logs,
val_results,
mode,
prefix='val_')
if mode == ModeKeys.TRAIN:
# Epochs only apply to `fit`.
callbacks.on_epoch_end(epoch, epoch_logs)
# Recreate dataset iterator for the next epoch.
if reset_dataset_after_each_epoch and epoch < epochs - 1:
generator = tf.compat.v1.data.make_one_shot_iterator(
original_dataset)
model._successful_loop_finish = True
callbacks._call_end_hook(mode)
if enqueuer is not None:
enqueuer.stop()
if should_set_learning_phase:
learning_phase_scope.__exit__(None, None, None)
if mode == ModeKeys.TRAIN:
return model.history
return results