def __init__(self, layer, call_args=None, call_kwargs=None, outputs=None):
call_args = [] if call_args is None else call_args
call_kwargs = {} if call_kwargs is None else call_kwargs
outputs = [] if outputs is None else outputs
self.layer = layer
self.is_input = not call_args and not call_kwargs
# These arguments are user-provided. Copy the structures here so that
# future user modifications do not affect the node's metadata.
# We copy using map_structure rather than python's shallow or deep copy,
# because the args can be data structures (so shallow copy is
# insufficient), but individual values might not support copy.copy
# or be too expensive to deep copy.
call_args = nest.map_structure(lambda t: t, call_args)
call_kwargs = nest.map_structure(lambda t: t, call_kwargs)
self.outputs = nest.map_structure(lambda t: t, outputs)
self.call_args = call_args
self.call_kwargs = call_kwargs
# Cached for performance.
self._flat_arguments = nest.flatten((self.call_args, self.call_kwargs))
# Used to avoid expensive `nest` operations in the most common case.
self._single_positional_tensor_passed = (not self.call_kwargs and len(
self.call_args) == 1 and tensor_util.is_tensor(self.call_args[0]))
if not keras_tensor.keras_tensors_enabled():
# Create TensorFlowOpLayers if needed.
for obj in self._flat_arguments:
if (isinstance(obj, ops.Tensor)
and base_layer_utils.needs_keras_history(
obj, ignore_call_context=True)):
base_layer_utils.create_keras_history(obj)
self._keras_inputs = []
self._keras_inputs_ids_and_indices = []
for i, ele in enumerate(self._flat_arguments):
if is_keras_tensor(ele):
self._keras_inputs.append(ele)
kt_id = str(id(ele))
kt_index = i
self._keras_inputs_ids_and_indices.append((kt_id, kt_index))
# Wire up Node to Layers.
self.layer._inbound_nodes.append(self)
for kt in self.keras_inputs:
inbound_layer = kt._keras_history.layer
if inbound_layer is not None: # `None` for `Input` tensors.
inbound_layer._outbound_nodes.append(self)
# Set metadata on outputs.
node_index = len(self.layer._inbound_nodes) - 1
for i, tensor in enumerate(nest.flatten(outputs)):
tensor._keras_history = KerasHistory(layer=layer,
node_index=node_index,
tensor_index=i)
# Cached for performance.
self.flat_input_ids = [str(id(t)) for t in self._keras_inputs]
self.flat_output_ids = [str(id(t)) for t in nest.flatten(self.outputs)]
def inference(self, inputs, *args, **kwargs):
call_context = base_layer_utils.call_context()
input_list = nest.flatten(inputs)
# We will attempt to build a TF graph if & only if all inputs are symbolic.
# This is always the case in graph mode. It can also be the case in eager
# mode when all inputs can be traced back to `keras.Input()` (when building
# models using the functional API).
build_graph = tf_utils.are_all_symbolic_tensors(input_list)
# Accept NumPy and scalar inputs by converting to Tensors.
if any(isinstance(x, (np.ndarray, float, int)) for x in input_list):
def _convert_non_tensor(x):
# Don't call `ops.convert_to_tensor` on all `inputs` because
# `SparseTensors` can't be converted to `Tensor`.
if isinstance(x, (np.ndarray, float, int)):
return ops.convert_to_tensor(x)
return x
inputs = nest.map_structure(_convert_non_tensor, inputs)
input_list = nest.flatten(inputs)
# Handle `mask` propagation from previous layer to current layer. Masks can
# be propagated explicitly via the `mask` argument, or implicitly via
# setting the `_keras_mask` attribute on the inputs to a Layer. Masks passed
# explicitly take priority.
mask_arg_passed_by_framework = False
input_masks = self._collect_input_masks(inputs, args, kwargs)
if (self._expects_mask_arg and input_masks is not None and
not self._call_arg_was_passed('mask', args, kwargs)):
mask_arg_passed_by_framework = True
kwargs['mask'] = input_masks
# If `training` argument was not explicitly passed, propagate `training`
# value from this layer's calling layer.
training_arg_passed_by_framework = False
# Priority 1: `training` was explicitly passed.
if self._call_arg_was_passed('training', args, kwargs):
training_value = self._get_call_arg_value('training', args, kwargs)
if not self._expects_training_arg:
kwargs.pop('training')
else:
training_value = None
# Priority 2: `training` was passed to a parent layer.
if call_context.training is not None:
training_value = call_context.training
# Priority 3a: `learning_phase()` has been set.
elif backend.global_learning_phase_is_set():
training_value = backend.learning_phase()
# Priority 3b: Pass the `learning_phase()` if in the Keras FuncGraph.
elif build_graph:
with backend.get_graph().as_default():
if base_layer_utils.is_in_keras_graph():
training_value = backend.learning_phase()
if self._expects_training_arg and training_value is not None:
# Force the training_value to be bool type which matches to the contract
# for layer/model call args.
if tensor_util.is_tensor(training_value):
training_value = math_ops.cast(training_value, dtypes.bool)
else:
training_value = bool(training_value)
kwargs['training'] = training_value
training_arg_passed_by_framework = True
# Only create Keras history if at least one tensor originates from a
# `keras.Input`. Otherwise this Layer may be being used outside the Keras
# framework.
if build_graph and base_layer_utils.needs_keras_history(inputs):
base_layer_utils.create_keras_history(inputs)
# Clear eager losses on top level model call.
# We are clearing the losses only on the top level model call and not on
# every layer/model call because layer/model may be reused.
if (base_layer_utils.is_in_eager_or_tf_function() and
not call_context.in_call):
self._clear_losses()
with call_context.enter(self, inputs, build_graph, training_value):
# Check input assumptions set after layer building, e.g. input shape.
if build_graph:
# Symbolic execution on symbolic tensors. We will attempt to build
# the corresponding TF subgraph inside `backend.get_graph()`
# TODO(reedwm): We should assert input compatibility after the inputs
# are casted, not before.
input_spec.assert_input_compatibility(self.input_spec, inputs,
self.name)
if (any(isinstance(x, ragged_tensor.RaggedTensor) for x in input_list)
and self._supports_ragged_inputs is False): # pylint: disable=g-bool-id-comparison
raise ValueError('Layer %s does not support RaggedTensors as input. '
'Inputs received: %s. You can try converting your '
'input to an uniform tensor.' % (self.name, inputs))
graph = backend.get_graph()
with graph.as_default(), backend.name_scope(self._name_scope()):
# Build layer if applicable (if the `build` method has been
# overridden).
self._maybe_build(inputs)
cast_inputs = self._maybe_cast_inputs(inputs)
# Wrapping `call` function in autograph to allow for dynamic control
# flow and control dependencies in call. We are limiting this to
# subclassed layers as autograph is strictly needed only for
# subclassed layers and models.
# tf_convert will respect the value of autograph setting in the
# enclosing tf.function, if any.
if (base_layer_utils.is_subclassed(self) and
not base_layer_utils.from_saved_model(self)):
call_fn = autograph.tf_convert(
self._inference, ag_ctx.control_status_ctx())
else:
call_fn = self._inference
if not self.dynamic:
try:
with base_layer_utils.autocast_context_manager(
self._compute_dtype):
# Add auto_control_deps in V2 when they are not already added by
# a `tf.function`.
if (ops.executing_eagerly_outside_functions() and
not base_layer_utils.is_in_eager_or_tf_function()):
with auto_control_deps.AutomaticControlDependencies() as acd:
outputs = call_fn(cast_inputs, *args, **kwargs)
# Wrap Tensors in `outputs` in `tf.identity` to avoid
# circular dependencies.
outputs = base_layer_utils.mark_as_return(outputs, acd)
else:
outputs = call_fn(cast_inputs, *args, **kwargs)
except errors.OperatorNotAllowedInGraphError as e:
raise TypeError('You are attempting to use Python control '
'flow in a layer that was not declared to be '
'dynamic. Pass `dynamic=True` to the class '
'constructor.\nEncountered error:\n"""\n' +
str(e) + '\n"""')
else:
# We will use static shape inference to return symbolic tensors
# matching the specifications of the layer outputs.
# Since `self.dynamic` is True, we will never attempt to
# run the underlying TF graph (which is disconnected).
# TODO(fchollet): consider py_func as an alternative, which
# would enable us to run the underlying graph if needed.
outputs = self._symbolic_call(inputs)
if outputs is None:
raise ValueError('A layer\'s `call` method should return a '
'Tensor or a list of Tensors, not None '
'(layer: ' + self.name + ').')
if base_layer_utils.have_all_keras_metadata(inputs):
if training_arg_passed_by_framework:
kwargs.pop('training')
if mask_arg_passed_by_framework:
kwargs.pop('mask')
inputs, outputs = self._set_connectivity_metadata_(
inputs, outputs, args, kwargs)
self._handle_activity_regularization(inputs, outputs)
self._set_mask_metadata(inputs, outputs, input_masks)
if hasattr(self, '_set_inputs') and not self.inputs:
# Subclassed network: explicitly set metadata normally set by
# a call to self._set_inputs().
# TODO(b/120997007): This should be done in Eager as well, but
# causes garbage collection issues because of the placeholders
# created on the default Keras graph.
self._set_inputs(inputs, outputs)
else:
# Eager execution on data tensors.
with backend.name_scope(self._name_scope()):
self._maybe_build(inputs)
cast_inputs = self._maybe_cast_inputs(inputs)
with base_layer_utils.autocast_context_manager(
self._compute_dtype):
outputs = self._inference(cast_inputs, *args, **kwargs)
self._handle_activity_regularization(inputs, outputs)
self._set_mask_metadata(inputs, outputs, input_masks)
return outputs
def __init__(self,
outbound_layer,
inbound_layers,
node_indices,
tensor_indices,
input_tensors,
output_tensors,
arguments=None):
# Layer instance (NOT a sequence)
if isinstance(outbound_layer, (list, tuple, dict)):
raise ValueError('`outbound_layer` should be a layer instance, '
'not a list, tuple, or, dict.')
# this is the layer that takes a nested structure of input tensors
# and turns them into a nested structure of output tensors.
# the current node will be added to
# the inbound_nodes of outbound_layer.
self.outbound_layer = outbound_layer
# The following 3 properties describe where
# the input tensors come from: which layers,
# and for each layer, which node and which
# tensor output of each node.
# Nested structure of layer instances.
self.inbound_layers = inbound_layers
# Nested structure of integers, 1:1 mapping with inbound_layers.
self.node_indices = node_indices
# Nested of integers, 1:1 mapping with inbound_layers.
self.tensor_indices = tensor_indices
# Following 2 properties:
# tensor inputs and outputs of outbound_layer.
# Nested structure of tensors. 1:1 mapping with inbound_layers.
self.input_tensors = input_tensors
# Nested structure of tensors, created by outbound_layer.call().
self.output_tensors = output_tensors
# Following 2 properties: input and output shapes.
# Nested structure of shape tuples, shapes of input_tensors.
self.input_shapes = nest.map_structure(backend.int_shape,
input_tensors)
# Nested structure of shape tuples, shapes of output_tensors.
self.output_shapes = nest.map_structure(backend.int_shape,
output_tensors)
# Optional keyword arguments to layer's `call`.
self.arguments = arguments
# Create Keras History for any Keras Tensors in `arguments`.
tensor_arguments = [
t for t in nest.flatten(self.arguments)
if isinstance(t, ops.Tensor)
]
for tensor_argument in tensor_arguments:
if base_layer_utils.needs_keras_history(tensor_argument,
ignore_call_context=True):
base_layer_utils.create_keras_history(tensor_argument)
# Add nodes to all layers involved.
for layer in nest.flatten(inbound_layers):
if layer is not None:
# For compatibility with external Keras, we use the deprecated
# accessor here.
layer.outbound_nodes.append(self)
# For compatibility with external Keras, we use the deprecated
# accessor here.
outbound_layer.inbound_nodes.append(self)
def _init_graph_network(self, inputs, outputs, name=None, **kwargs):
generic_utils.validate_kwargs(
kwargs, {'trainable'},
'Functional models may only specify `name` and `trainable` keyword '
'arguments during initialization. Got an unexpected argument:')
# Normalize and set self.inputs, self.outputs.
if isinstance(inputs, list) and len(nest.flatten(inputs)) == 1:
inputs = inputs[0]
if isinstance(outputs, list) and len(nest.flatten(outputs)) == 1:
outputs = outputs[0]
self._nested_outputs = outputs
self._nested_inputs = inputs
self.inputs = nest.flatten(inputs)
self.outputs = nest.flatten(outputs)
if any(not hasattr(tensor, '_keras_history') for tensor in self.outputs):
base_layer_utils.create_keras_history(self._nested_outputs)
self._base_init(name=name, **kwargs)
self._validate_graph_inputs_and_outputs()
# A Network does not create weights of its own, thus it is already
# built.
self.built = True
self._compute_output_and_mask_jointly = True
self._is_graph_network = True
# `_expects_training_arg` is True since the `training` argument is always
# present in the signature of the `call` method of a graph network.
self._expects_training_arg = True
self._expects_mask_arg = True
# A graph network does not autocast inputs, as its layers will cast them
# instead.
self._autocast = False
self._input_layers = []
self._output_layers = []
self._input_coordinates = []
self._output_coordinates = []
self._supports_ragged_inputs = None
# This is for performance optimization when calling the Network on new
# inputs. Every time the Network is called on a set on input tensors,
# we compute the output tensors, output masks and output shapes in one pass,
# then cache them here. When any of these outputs is queried later, we
# retrieve it from there instead of recomputing it.
self._output_mask_cache = {}
self._output_tensor_cache = {}
self._output_shape_cache = {}
# Build self._output_layers:
for x in self.outputs:
layer, node_index, tensor_index = x._keras_history # pylint: disable=protected-access
self._output_layers.append(layer)
self._output_coordinates.append((layer, node_index, tensor_index))
# Build self._input_layers:
for x in self.inputs:
layer, node_index, tensor_index = x._keras_history # pylint: disable=protected-access
# It's supposed to be an input layer, so only one node
# and one tensor output.
assert node_index == 0
assert tensor_index == 0
self._input_layers.append(layer)
self._input_coordinates.append((layer, node_index, tensor_index))
# Keep track of the network's nodes and layers.
nodes, nodes_by_depth, layers, _ = _map_graph_network(
self.inputs, self.outputs)
self._network_nodes = nodes
self._nodes_by_depth = nodes_by_depth
self._layers = layers
self._layer_call_argspecs = {}
for layer in self._layers:
self._layer_call_argspecs[layer] = tf_inspect.getfullargspec(layer.call)
layer._attribute_sentinel.add_parent(self._attribute_sentinel)
self._track_layers(layers)
# Create the node linking internal inputs to internal outputs.
node_module.Node(
outbound_layer=self,
inbound_layers=[],
node_indices=[],
tensor_indices=[],
input_tensors=self._nested_inputs,
output_tensors=self._nested_outputs)
# Build self.input_names and self.output_names.
self._set_output_names()
self.input_names = []
self._feed_input_names = []
self._feed_inputs = []
self._feed_input_shapes = []
for layer in self._input_layers:
self.input_names.append(layer.name)
if layer.is_placeholder:
self._feed_input_names.append(layer.name)
# Use batch_input_shape here because non-eager composite tensors may not
# have a shape attribute that's meaningful (sparse, for instance, has
# a tensor that's non-constant and needs to be fed). This means that
# input layers that create placeholders will need to have the
# batch_input_shape attr to allow for input shape validation.
self._feed_input_shapes.append(layer._batch_input_shape)
self._feed_inputs.append(layer.input)
