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scopes.py
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scopes.py
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# Copyright 2016 Google Inc. All Rights Reserved.
#
# 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.
# ==============================================================================
"""Contains the new arg_scope used for TF-Slim ops.
Allows one to define models much more compactly by eliminating boilerplate
code. This is accomplished through the use of argument scoping (arg_scope).
Example of how to use scopes.arg_scope:
with scopes.arg_scope(ops.conv2d, padding='SAME',
stddev=0.01, weight_decay=0.0005):
net = ops.conv2d(inputs, 64, [11, 11], 4, padding='VALID', scope='conv1')
net = ops.conv2d(net, 256, [5, 5], scope='conv2')
The first call to conv2d will overwrite padding:
ops.conv2d(inputs, 64, [11, 11], 4, padding='VALID',
stddev=0.01, weight_decay=0.0005, scope='conv1')
The second call to Conv will use predefined args:
ops.conv2d(inputs, 256, [5, 5], padding='SAME',
stddev=0.01, weight_decay=0.0005, scope='conv2')
Example of how to reuse an arg_scope:
with scopes.arg_scope(ops.conv2d, padding='SAME',
stddev=0.01, weight_decay=0.0005) as conv2d_arg_scope:
net = ops.conv2d(net, 256, [5, 5], scope='conv1')
....
with scopes.arg_scope(conv2d_arg_scope):
net = ops.conv2d(net, 256, [5, 5], scope='conv2')
Example of how to use scopes.add_arg_scope:
@scopes.add_arg_scope
def conv2d(*args, **kwargs)
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import contextlib
import functools
from tensorflow.python.framework import ops
_ARGSTACK_KEY = ("__arg_stack",)
_DECORATED_OPS = set()
def _get_arg_stack():
stack = ops.get_collection(_ARGSTACK_KEY)
if stack:
return stack[0]
else:
stack = [{}]
ops.add_to_collection(_ARGSTACK_KEY, stack)
return stack
def _current_arg_scope():
stack = _get_arg_stack()
return stack[-1]
def _add_op(op):
key_op = (op.__module__, op.__name__)
if key_op not in _DECORATED_OPS:
_DECORATED_OPS.add(key_op)
@contextlib.contextmanager
def arg_scope(list_ops_or_scope, **kwargs):
"""Stores the default arguments for the given set of list_ops.
For usage, please see examples at top of the file.
Args:
list_ops_or_scope: List or tuple of operations to set argument scope for or
a dictionary containg the current scope. When list_ops_or_scope is a dict,
kwargs must be empty. When list_ops_or_scope is a list or tuple, then
every op in it need to be decorated with @add_arg_scope to work.
**kwargs: keyword=value that will define the defaults for each op in
list_ops. All the ops need to accept the given set of arguments.
Yields:
the current_scope, which is a dictionary of {op: {arg: value}}
Raises:
TypeError: if list_ops is not a list or a tuple.
ValueError: if any op in list_ops has not be decorated with @add_arg_scope.
"""
if isinstance(list_ops_or_scope, dict):
# Assumes that list_ops_or_scope is a scope that is being reused.
if kwargs:
raise ValueError("When attempting to re-use a scope by suppling a"
"dictionary, kwargs must be empty.")
current_scope = list_ops_or_scope.copy()
try:
_get_arg_stack().append(current_scope)
yield current_scope
finally:
_get_arg_stack().pop()
else:
# Assumes that list_ops_or_scope is a list/tuple of ops with kwargs.
if not isinstance(list_ops_or_scope, (list, tuple)):
raise TypeError("list_ops_or_scope must either be a list/tuple or reused"
"scope (i.e. dict)")
try:
current_scope = _current_arg_scope().copy()
for op in list_ops_or_scope:
key_op = (op.__module__, op.__name__)
if not has_arg_scope(op):
raise ValueError("%s is not decorated with @add_arg_scope", key_op)
if key_op in current_scope:
current_kwargs = current_scope[key_op].copy()
current_kwargs.update(kwargs)
current_scope[key_op] = current_kwargs
else:
current_scope[key_op] = kwargs.copy()
_get_arg_stack().append(current_scope)
yield current_scope
finally:
_get_arg_stack().pop()
def add_arg_scope(func):
"""Decorates a function with args so it can be used within an arg_scope.
Args:
func: function to decorate.
Returns:
A tuple with the decorated function func_with_args().
"""
@functools.wraps(func)
def func_with_args(*args, **kwargs):
current_scope = _current_arg_scope()
current_args = kwargs
key_func = (func.__module__, func.__name__)
if key_func in current_scope:
current_args = current_scope[key_func].copy()
current_args.update(kwargs)
return func(*args, **current_args)
_add_op(func)
return func_with_args
def has_arg_scope(func):
"""Checks whether a func has been decorated with @add_arg_scope or not.
Args:
func: function to check.
Returns:
a boolean.
"""
key_op = (func.__module__, func.__name__)
return key_op in _DECORATED_OPS

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