""" Model / state_dict utils
Hacked together by / Copyright 2020 Ross Wightman
"""
import fnmatch
import torch
from torchvision.ops.misc import FrozenBatchNorm2d
from timm.layers import BatchNormAct2d, SyncBatchNormAct, FrozenBatchNormAct2d,\
freeze_batch_norm_2d, unfreeze_batch_norm_2d
from .model_ema import ModelEma
def unwrap_model(model):
if isinstance(model, ModelEma):
return unwrap_model(model.ema)
else:
return model.module if hasattr(model, 'module') else model
def get_state_dict(model, unwrap_fn=unwrap_model):
return unwrap_fn(model).state_dict()
def avg_sq_ch_mean(model, input, output):
""" calculate average channel square mean of output activations
"""
return torch.mean(output.mean(axis=[0, 2, 3]) ** 2).item()
def avg_ch_var(model, input, output):
""" calculate average channel variance of output activations
"""
return torch.mean(output.var(axis=[0, 2, 3])).item()
def avg_ch_var_residual(model, input, output):
""" calculate average channel variance of output activations
"""
return torch.mean(output.var(axis=[0, 2, 3])).item()
class ActivationStatsHook:
"""Iterates through each of `model`'s modules and matches modules using unix pattern
matching based on `hook_fn_locs` and registers `hook_fn` to the module if there is
a match.
Arguments:
model (nn.Module): model from which we will extract the activation stats
hook_fn_locs (List[str]): List of `hook_fn` locations based on Unix type string
matching with the name of model's modules.
hook_fns (List[Callable]): List of hook functions to be registered at every
module in `layer_names`.
Inspiration from https://docs.fast.ai/callback.hook.html.
Refer to https://gist.github.com/amaarora/6e56942fcb46e67ba203f3009b30d950 for an example
on how to plot Signal Propogation Plots using `ActivationStatsHook`.
"""
def __init__(self, model, hook_fn_locs, hook_fns):
self.model = model
self.hook_fn_locs = hook_fn_locs
self.hook_fns = hook_fns
if len(hook_fn_locs) != len(hook_fns):
raise ValueError("Please provide `hook_fns` for each `hook_fn_locs`, \
their lengths are different.")
self.stats = dict((hook_fn.__name__, []) for hook_fn in hook_fns)
for hook_fn_loc, hook_fn in zip(hook_fn_locs, hook_fns):
self.register_hook(hook_fn_loc, hook_fn)
def _create_hook(self, hook_fn):
def append_activation_stats(module, input, output):
out = hook_fn(module, input, output)
self.stats[hook_fn.__name__].append(out)
return append_activation_stats
def register_hook(self, hook_fn_loc, hook_fn):
for name, module in self.model.named_modules():
if not fnmatch.fnmatch(name, hook_fn_loc):
continue
module.register_forward_hook(self._create_hook(hook_fn))
def extract_spp_stats(
model,
hook_fn_locs,
hook_fns,
input_shape=[8, 3, 224, 224]):
"""Extract average square channel mean and variance of activations during
forward pass to plot Signal Propogation Plots (SPP).
Paper: https://arxiv.org/abs/2101.08692
Example Usage: https://gist.github.com/amaarora/6e56942fcb46e67ba203f3009b30d950
"""
x = torch.normal(0., 1., input_shape)
hook = ActivationStatsHook(model, hook_fn_locs=hook_fn_locs, hook_fns=hook_fns)
_ = model(x)
return hook.stats
def _freeze_unfreeze(root_module, submodules=[], include_bn_running_stats=True, mode='freeze'):
"""
Freeze or unfreeze parameters of the specified modules and those of all their hierarchical descendants. This is
done in place.
Args:
root_module (nn.Module, optional): Root module relative to which the `submodules` are referenced.
submodules (list[str]): List of modules for which the parameters will be (un)frozen. They are to be provided as
named modules relative to the root module (accessible via `root_module.named_modules()`). An empty list
means that the whole root module will be (un)frozen. Defaults to []
include_bn_running_stats (bool): Whether to also (un)freeze the running statistics of batch norm 2d layers.
Defaults to `True`.
mode (bool): Whether to freeze ("freeze") or unfreeze ("unfreeze"). Defaults to `"freeze"`.
"""
assert mode in ["freeze", "unfreeze"], '`mode` must be one of "freeze" or "unfreeze"'
if isinstance(root_module, (
torch.nn.modules.batchnorm.BatchNorm2d,
torch.nn.modules.batchnorm.SyncBatchNorm,
BatchNormAct2d,
SyncBatchNormAct,
)):
# Raise assertion here because we can't convert it in place
raise AssertionError(
"You have provided a batch norm layer as the `root module`. Please use "
"`timm.utils.model.freeze_batch_norm_2d` or `timm.utils.model.unfreeze_batch_norm_2d` instead.")
if isinstance(submodules, str):
submodules = [submodules]
named_modules = submodules
submodules = [root_module.get_submodule(m) for m in submodules]
if not len(submodules):
named_modules, submodules = list(zip(*root_module.named_children()))
for n, m in zip(named_modules, submodules):
# (Un)freeze parameters
for p in m.parameters():
p.requires_grad = False if mode == 'freeze' else True
if include_bn_running_stats:
# Helper to add submodule specified as a named_module
def _add_submodule(module, name, submodule):
split = name.rsplit('.', 1)
if len(split) > 1:
module.get_submodule(split[0]).add_module(split[1], submodule)
else:
module.add_module(name, submodule)
# Freeze batch norm
if mode == 'freeze':
res = freeze_batch_norm_2d(m)
# It's possible that `m` is a type of BatchNorm in itself, in which case `unfreeze_batch_norm_2d` won't
# convert it in place, but will return the converted result. In this case `res` holds the converted
# result and we may try to re-assign the named module
if isinstance(m, (
torch.nn.modules.batchnorm.BatchNorm2d,
torch.nn.modules.batchnorm.SyncBatchNorm,
BatchNormAct2d,
SyncBatchNormAct,
)):
_add_submodule(root_module, n, res)
# Unfreeze batch norm
else:
res = unfreeze_batch_norm_2d(m)
# Ditto. See note above in mode == 'freeze' branch
if isinstance(m, (FrozenBatchNorm2d, FrozenBatchNormAct2d)):
_add_submodule(root_module, n, res)
def freeze(root_module, submodules=[], include_bn_running_stats=True):
"""
Freeze parameters of the specified modules and those of all their hierarchical descendants. This is done in place.
Args:
root_module (nn.Module): Root module relative to which `submodules` are referenced.
submodules (list[str]): List of modules for which the parameters will be frozen. They are to be provided as
named modules relative to the root module (accessible via `root_module.named_modules()`). An empty list
means that the whole root module will be frozen. Defaults to `[]`.
include_bn_running_stats (bool): Whether to also freeze the running statistics of `BatchNorm2d` and
`SyncBatchNorm` layers. These will be converted to `FrozenBatchNorm2d` in place. Hint: During fine tuning,
it's good practice to freeze batch norm stats. And note that these are different to the affine parameters
which are just normal PyTorch parameters. Defaults to `True`.
Hint: If you want to freeze batch norm ONLY, use `timm.utils.model.freeze_batch_norm_2d`.
Examples::
>>> model = timm.create_model('resnet18')
>>> # Freeze up to and including layer2
>>> submodules = [n for n, _ in model.named_children()]
>>> print(submodules)
['conv1', 'bn1', 'act1', 'maxpool', 'layer1', 'layer2', 'layer3', 'layer4', 'global_pool', 'fc']
>>> freeze(model, submodules[:submodules.index('layer2') + 1])
>>> # Check for yourself that it works as expected
>>> print(model.layer2[0].conv1.weight.requires_grad)
False
>>> print(model.layer3[0].conv1.weight.requires_grad)
True
>>> # Unfreeze
>>> unfreeze(model)
"""
_freeze_unfreeze(root_module, submodules, include_bn_running_stats=include_bn_running_stats, mode="freeze")
def unfreeze(root_module, submodules=[], include_bn_running_stats=True):
"""
Unfreeze parameters of the specified modules and those of all their hierarchical descendants. This is done in place.
Args:
root_module (nn.Module): Root module relative to which `submodules` are referenced.
submodules (list[str]): List of submodules for which the parameters will be (un)frozen. They are to be provided
as named modules relative to the root module (accessible via `root_module.named_modules()`). An empty
list means that the whole root module will be unfrozen. Defaults to `[]`.
include_bn_running_stats (bool): Whether to also unfreeze the running statistics of `FrozenBatchNorm2d` layers.
These will be converted to `BatchNorm2d` in place. Defaults to `True`.
See example in docstring for `freeze`.
"""
_freeze_unfreeze(root_module, submodules, include_bn_running_stats=include_bn_running_stats, mode="unfreeze")