#!/usr/bin/env python
# ******************************************************************************
# Copyright 2023 Brainchip Holdings Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ******************************************************************************
"""
Utility methods to insert layers in a model.
"""
__all__ = ['insert_layer', 'insert_rescaling', 'insert_in_config']
from copy import deepcopy
from keras.layers import serialize, InputLayer, Rescaling
from keras.models import Model, Sequential
from .transforms_utils import (get_layer_index, inbound_node_generator,
replace_layer_name_for_connection_info, get_layers_by_type)
from ..utils import apply_weights_to_model
from ...layers.quantizers import OutputQuantizer, Dequantizer
def insert_in_config(model, target_layer_name, new_layer, config, outbound_names=None):
""" Inserts the given layer in the model after the layer with the name target_layer_name by
editing the given configuration.
Args:
model (keras.Model): the model to update
target_layer_name (str): name of the layer after which to insert a layer
new_layer (keras.layers.Layer): layer to insert
config (dict): model dict config being updated
outbound_names (list, optional): list of outbounds layers names for the inserted
layer. When not specified, the outbound_names outbounds are retrieved from the given
model. Providing incoherent names will result in an invalid model graph. Defaults to
None.
"""
layers_config = config['layers']
# Prepare the layer configuration to be inserted
new_layer_config = serialize(new_layer)
# Handling sequential and functional models differently:
# - sequential models 'layers' configuration is a sorted list of the layers, so we just need
# to insert the new layer within that list,
# - for functional models, the layers inbound and outbounds are updated first
if not isinstance(model, Sequential):
# The layer name is added to the configuration
new_layer_config['name'] = new_layer.name
# Retrieve target_layer outbounds if None specified.
if outbound_names is None:
target_outbounds = model.get_layer(target_layer_name).outbound_nodes
outbound_names = [outbound.layer.name for outbound in target_outbounds]
# OutputQuantizer does not support multiple inputs so target layers with multiple outputs
# are rejected
if len(outbound_names) > 1 and isinstance(new_layer, OutputQuantizer):
raise RuntimeError("Inserting an OutputQuantizer after a layer with multiple outputs "
"is not supported.")
if len(outbound_names):
# Initialize the new layer inbounds
new_layer_inbounds = []
# Replace inbounds from the layers after the target layer with the inserted layer
outbound_ids = [get_layer_index(layers_config, outbound) for outbound in outbound_names]
for id in outbound_ids:
for inbound_node in inbound_node_generator(layers_config[id]):
if isinstance(inbound_node, dict):
inbound_node = inbound_node.values()
for connection_info in inbound_node:
matched = replace_layer_name_for_connection_info(connection_info,
target_layer_name,
new_layer.name)
# Store the replaced inbound as it will later be used by the inserted layer
if matched and matched not in new_layer_inbounds:
new_layer_inbounds.append(matched)
# Set the inserted layer inbounds
new_layer_config['inbound_nodes'] = [new_layer_inbounds]
else:
# If target layer has no outbounds (ie. it's a model output), update the model
# output layers list
for index, out_layer in enumerate(config['output_layers']):
if out_layer[0] == target_layer_name:
config['output_layers'][index][0] = new_layer.name
# The inserted layer takes the target layer as its inbound
new_layer_config['inbound_nodes'] = [[[target_layer_name, 0, 0, {}]]]
# The new layer configuration can now be inserted into the layers config
layers_config.insert(get_layer_index(layers_config, target_layer_name) + 1, new_layer_config)
def _insert_layer(model, target_layer_name, new_layer):
""" Inserts the given layer in the model after the layer with the name target_layer_name.
Args:
model (keras.Model): the model to update
target_layer_name (str): name of the layer after which to insert a layer
new_layer (keras.layers.Layer): layer to insert
Returns:
keras.Model: the new model
"""
# Check that the model has a layer with then given target_layer_name
if not any(ly.name == target_layer_name for ly in model.layers):
raise ValueError(f'{target_layer_name} not found in model.')
# get_config documentation mentions that a copy should be made when planning to modify the
# config
config = deepcopy(model.get_config())
# Insert layer in config graph
insert_in_config(model, target_layer_name, new_layer, config)
# Reconstruct model from the config
if isinstance(model, Sequential):
new_model = Sequential.from_config(config)
else:
new_model = Model.from_config(config)
# Load original weights
variables_dict = {var.name: var for var in model.variables}
apply_weights_to_model(new_model, variables_dict, False)
return new_model
[docs]
def insert_layer(model, target_layer_name, new_layer):
""" Inserts the given layer in the model after the layer with the name target_layer_name.
Note that new_layer type is restricted to (OutputQuantizer, Dequantizer).
Args:
model (keras.Model): the model to update
target_layer_name (str): name of the layer after which to insert a layer
new_layer (keras.layers.Layer): layer to insert
Raises:
ValueError: when target_layer_name is not found in model or new_layer is not in
(OutputQuantizer, Dequantizer)
Returns:
keras.Model: the new model
"""
# Check added layer type
if not isinstance(new_layer, (OutputQuantizer, Dequantizer)):
raise ValueError(f'Inserted layer must be of type OutputQuantizer or Dequantizer, \
`received {type(new_layer)}.')
return _insert_layer(model, target_layer_name, new_layer)
[docs]
def insert_rescaling(model, scale, offset):
""" Inserts a Rescaling as first layer of the Model (after the Input)
Args:
model (keras.Model): the model to update
scale (float): the Rescaling scale
offset (float): the Rescaling offset
Raises:
ValueError: when the Model does not have an Input layer.
Returns:
keras.Model: the new model
"""
first_layers = get_layers_by_type(model, InputLayer)
if len(first_layers) == 0:
raise ValueError("Inserting a Rescaling layer in a Model without an Input layer is not"
" supported.")
for target_layer in first_layers:
model = _insert_layer(model, target_layer.name, Rescaling(scale, offset))
return model