def _build_pnasnet_base(images,
normal_cell,
num_classes,
hparams,
is_training,
final_endpoint=None):
"""Constructs a PNASNet image model."""
end_points = {}
def add_and_check_endpoint(endpoint_name, net):
end_points[endpoint_name] = net
return final_endpoint and (endpoint_name == final_endpoint)
# Find where to place the reduction cells or stride normal cells
reduction_indices = nasnet_utils.calc_reduction_layers(
hparams.num_cells, hparams.num_reduction_layers)
# pylint: disable=protected-access
stem = lambda: nasnet._imagenet_stem(images, hparams, normal_cell)
# pylint: enable=protected-access
net, cell_outputs = stem()
if add_and_check_endpoint('Stem', net):
return net, end_points
# Setup for building in the auxiliary head.
aux_head_cell_idxes = []
if len(reduction_indices) >= 2:
aux_head_cell_idxes.append(reduction_indices[1] - 1)
# Run the cells
filter_scaling = 1.0
# true_cell_num accounts for the stem cells
true_cell_num = 2
activation_fn = tf.nn.relu6 if hparams.use_bounded_activation else tf.nn.relu
for cell_num in range(hparams.num_cells):
is_reduction = cell_num in reduction_indices
stride = 2 if is_reduction else 1
if is_reduction: filter_scaling *= hparams.filter_scaling_rate
if hparams.skip_reduction_layer_input or not is_reduction:
prev_layer = cell_outputs[-2]
net = normal_cell(
net,
scope='cell_{}'.format(cell_num),
filter_scaling=filter_scaling,
stride=stride,
prev_layer=prev_layer,
cell_num=true_cell_num)
if add_and_check_endpoint('Cell_{}'.format(cell_num), net):
return net, end_points
true_cell_num += 1
cell_outputs.append(net)
if (hparams.use_aux_head and cell_num in aux_head_cell_idxes and
num_classes and is_training):
aux_net = activation_fn(net)
# pylint: disable=protected-access
nasnet._build_aux_head(aux_net, end_points, num_classes, hparams,
scope='aux_{}'.format(cell_num))
# pylint: enable=protected-access
# Final softmax layer
with tf.variable_scope('final_layer'):
net = activation_fn(net)
net = nasnet_utils.global_avg_pool(net)
if add_and_check_endpoint('global_pool', net) or not num_classes:
return net, end_points
net = slim.dropout(net, hparams.dense_dropout_keep_prob, scope='dropout')
logits = slim.fully_connected(net, num_classes)
if add_and_check_endpoint('Logits', logits):
return net, end_points
predictions = tf.nn.softmax(logits, name='predictions')
if add_and_check_endpoint('Predictions', predictions):
return net, end_points
return logits, end_points
def _build_pnasnet_base(images,
normal_cell,
num_classes,
hparams,
is_training,
final_endpoint=None):
"""Constructs a PNASNet image model."""
end_points = {}
def add_and_check_endpoint(endpoint_name, net):
end_points[endpoint_name] = net
return final_endpoint and (endpoint_name == final_endpoint)
# Find where to place the reduction cells or stride normal cells
reduction_indices = nasnet_utils.calc_reduction_layers(
hparams.num_cells, hparams.num_reduction_layers)
# pylint: disable=protected-access
stem = lambda: nasnet._imagenet_stem(images, hparams, normal_cell)
# pylint: enable=protected-access
net, cell_outputs = stem()
if add_and_check_endpoint('Stem', net):
return net, end_points
# Setup for building in the auxiliary head.
aux_head_cell_idxes = []
if len(reduction_indices) >= 2:
aux_head_cell_idxes.append(reduction_indices[1] - 1)
# Run the cells
filter_scaling = 1.0
# true_cell_num accounts for the stem cells
true_cell_num = 2
for cell_num in range(hparams.num_cells):
is_reduction = cell_num in reduction_indices
stride = 2 if is_reduction else 1
if is_reduction: filter_scaling *= hparams.filter_scaling_rate
prev_layer = cell_outputs[-2]
net = normal_cell(
net,
scope='cell_{}'.format(cell_num),
filter_scaling=filter_scaling,
stride=stride,
prev_layer=prev_layer,
cell_num=true_cell_num)
if add_and_check_endpoint('Cell_{}'.format(cell_num), net):
return net, end_points
true_cell_num += 1
cell_outputs.append(net)
if (hparams.use_aux_head and cell_num in aux_head_cell_idxes and
num_classes and is_training):
aux_net = tf.nn.relu(net)
# pylint: disable=protected-access
nasnet._build_aux_head(aux_net, end_points, num_classes, hparams,
scope='aux_{}'.format(cell_num))
# pylint: enable=protected-access
# Final softmax layer
with tf.variable_scope('final_layer'):
net = tf.nn.relu(net)
net = nasnet_utils.global_avg_pool(net)
if add_and_check_endpoint('global_pool', net) or not num_classes:
return net, end_points
net = slim.dropout(net, hparams.dense_dropout_keep_prob, scope='dropout')
logits = slim.fully_connected(net, num_classes)
if add_and_check_endpoint('Logits', logits):
return net, end_points
predictions = tf.nn.softmax(logits, name='predictions')
if add_and_check_endpoint('Predictions', predictions):
return net, end_points
return logits, end_points
def stem():
return nasnet._imagenet_stem(images, hparams, normal_cell)