tensorflow Method源码阅读之 fully_connected

def fully_connected(inputs,
num_outputs,
activation_fn=nn.relu,
normalizer_fn=None,
normalizer_params=None,
weights_initializer=initializers.xavier_initializer(),
weights_regularizer=None,
biases_initializer=init_ops.zeros_initializer(),
biases_regularizer=None,
reuse=None,
variables_collections=None,
outputs_collections=None,
trainable=True,
scope=None):
"""Adds a fully connected layer. `fully_connected` creates a variable called `weights`, representing a fully
connected weight matrix, which is multiplied by the `inputs` to produce a
`Tensor` of hidden units. If a `normalizer_fn` is provided (such as
`batch_norm`), it is then applied. Otherwise, if `normalizer_fn` is
None and a `biases_initializer` is provided then a `biases` variable would be
created and added the hidden units. Finally, if `activation_fn` is not `None`,
it is applied to the hidden units as well. Note: that if `inputs` have a rank greater than 2, then `inputs` is flattened
prior to the initial matrix multiply by `weights`. Args:
inputs: A tensor of at least rank 2 and static value for the last dimension;
i.e. `[batch_size, depth]`, `[None, None, None, channels]`.
num_outputs: Integer or long, the number of output units in the layer.
activation_fn: Activation function. The default value is a ReLU function.
Explicitly set it to None to skip it and maintain a linear activation.
normalizer_fn: Normalization function to use instead of `biases`. If
`normalizer_fn` is provided then `biases_initializer` and
`biases_regularizer` are ignored and `biases` are not created nor added.
default set to None for no normalizer function
normalizer_params: Normalization function parameters.
weights_initializer: An initializer for the weights.
weights_regularizer: Optional regularizer for the weights.
biases_initializer: An initializer for the biases. If None skip biases.
biases_regularizer: Optional regularizer for the biases.
reuse: Whether or not the layer and its variables should be reused. To be
able to reuse the layer scope must be given.
variables_collections: Optional list of collections for all the variables or
a dictionary containing a different list of collections per variable.
outputs_collections: Collection to add the outputs.
trainable: If `True` also add variables to the graph collection
`GraphKeys.TRAINABLE_VARIABLES` (see tf.Variable).
scope: Optional scope for variable_scope. Returns:
The tensor variable representing the result of the series of operations. Raises:
ValueError: If x has rank less than 2 or if its last dimension is not set.
"""
if not isinstance(num_outputs, six.integer_types):
raise ValueError('num_outputs should be int or long, got %s.' %
(num_outputs,)) layer_variable_getter = _build_variable_getter({
'bias': 'biases',
'kernel': 'weights'
}) with variable_scope.variable_scope(
scope,
'fully_connected', [inputs],
reuse=reuse,
custom_getter=layer_variable_getter) as sc:
inputs = ops.convert_to_tensor(inputs)
layer = core_layers.Dense(
units=num_outputs,
activation=None,
use_bias=not normalizer_fn and biases_initializer,
kernel_initializer=weights_initializer,
bias_initializer=biases_initializer,
kernel_regularizer=weights_regularizer,
bias_regularizer=biases_regularizer,
activity_regularizer=None,
trainable=trainable,
name=sc.name,
dtype=inputs.dtype.base_dtype,
_scope=sc,
_reuse=reuse)
outputs = layer.apply(inputs) # Add variables to collections.
_add_variable_to_collections(layer.kernel, variables_collections, 'weights')
if layer.bias is not None:
_add_variable_to_collections(layer.bias, variables_collections, 'biases') # Apply normalizer function / layer.
if normalizer_fn is not None:
if not normalizer_params:
normalizer_params = {}
outputs = normalizer_fn(outputs, **normalizer_params) if activation_fn is not None:
outputs = activation_fn(outputs) return utils.collect_named_outputs(outputs_collections, sc.name, outputs)