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2026-07-13 13:21:43 +08:00

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Python

"""Callback and helper function to add hooks in models
Docs: https://docs.fast.ai/callback.hook.html.md"""
# AUTOGENERATED! DO NOT EDIT! File to edit: ../../nbs/15_callback.hook.ipynb.
# %% auto #0
__all__ = ['Hook', 'hook_output', 'Hooks', 'hook_outputs', 'dummy_eval', 'model_sizes', 'num_features_model', 'has_params',
'HookCallback', 'total_params', 'layer_info', 'module_summary', 'ActivationStats']
# %% ../../nbs/15_callback.hook.ipynb #19fb2c41
from ..basics import *
# %% ../../nbs/15_callback.hook.ipynb #e4cd49d7
@docs
class Hook():
"Create a hook on `m` with `hook_func`."
def __init__(self, m, hook_func, is_forward=True, detach=True, cpu=False, gather=False):
store_attr('hook_func,detach,cpu,gather')
f = m.register_forward_hook if is_forward else m.register_backward_hook
self.hook = f(self.hook_fn)
self.stored,self.removed = None,False
def hook_fn(self, module, input, output):
"Applies `hook_func` to `module`, `input`, `output`."
if self.detach:
input,output = to_detach(input, cpu=self.cpu, gather=self.gather),to_detach(output, cpu=self.cpu, gather=self.gather)
self.stored = self.hook_func(module, input, output)
def remove(self):
"Remove the hook from the model."
if not self.removed:
self.hook.remove()
self.removed=True
def __enter__(self, *args): return self
def __exit__(self, *args): self.remove()
_docs = dict(__enter__="Register the hook",
__exit__="Remove the hook")
# %% ../../nbs/15_callback.hook.ipynb #f65e044f
def _hook_inner(m,i,o): return o if isinstance(o,Tensor) or is_listy(o) else list(o)
def hook_output(module, detach=True, cpu=False, grad=False):
"Return a `Hook` that stores activations of `module` in `self.stored`"
return Hook(module, _hook_inner, detach=detach, cpu=cpu, is_forward=not grad)
# %% ../../nbs/15_callback.hook.ipynb #659fe775
@docs
class Hooks():
"Create several hooks on the modules in `ms` with `hook_func`."
def __init__(self, ms, hook_func, is_forward=True, detach=True, cpu=False):
self.hooks = [Hook(m, hook_func, is_forward, detach, cpu) for m in ms]
def __getitem__(self,i): return self.hooks[i]
def __len__(self): return len(self.hooks)
def __iter__(self): return iter(self.hooks)
@property
def stored(self): return L(o.stored for o in self)
def remove(self):
"Remove the hooks from the model."
for h in self.hooks: h.remove()
def __enter__(self, *args): return self
def __exit__ (self, *args): self.remove()
_docs = dict(stored = "The states saved in each hook.",
__enter__="Register the hooks",
__exit__="Remove the hooks")
# %% ../../nbs/15_callback.hook.ipynb #249957bd
def hook_outputs(modules, detach=True, cpu=False, grad=False):
"Return `Hooks` that store activations of all `modules` in `self.stored`"
return Hooks(modules, _hook_inner, detach=detach, cpu=cpu, is_forward=not grad)
# %% ../../nbs/15_callback.hook.ipynb #91609b59
def dummy_eval(m, size=(64,64)):
"Evaluate `m` on a dummy input of a certain `size`"
ch_in = in_channels(m)
x = one_param(m).new(1, ch_in, *size).requires_grad_(False).uniform_(-1.,1.)
with torch.no_grad(): return m.eval()(x)
# %% ../../nbs/15_callback.hook.ipynb #9f3ac0f5
def model_sizes(m, size=(64,64)):
"Pass a dummy input through the model `m` to get the various sizes of activations."
with hook_outputs(m) as hooks:
_ = dummy_eval(m, size=size)
return [o.stored.shape for o in hooks]
# %% ../../nbs/15_callback.hook.ipynb #c4e83e37
def num_features_model(m):
"Return the number of output features for `m`."
sz,ch_in = 32,in_channels(m)
while True:
#Trying for a few sizes in case the model requires a big input size.
try:
return model_sizes(m, (sz,sz))[-1][1]
except Exception as e:
sz *= 2
if sz > 2048: raise e
# %% ../../nbs/15_callback.hook.ipynb #aeaa55a9
def has_params(m):
"Check if `m` has at least one parameter"
return len(list(m.parameters())) > 0
# %% ../../nbs/15_callback.hook.ipynb #4b78dda7
@funcs_kwargs
class HookCallback(Callback):
"`Callback` that can be used to register hooks on `modules`"
_methods = ["hook"]
hook = noops
def __init__(self, modules=None, every=None, remove_end=True, is_forward=True, detach=True, cpu=True, include_paramless=False , **kwargs):
store_attr('modules,every,remove_end,is_forward,detach,cpu, include_paramless')
assert not kwargs
def before_fit(self):
"Register the `Hooks` on `self.modules`."
if self.modules is None: self.modules = [m for m in flatten_model(self.model) if self.include_paramless or has_params(m)]
if self.every is None: self._register()
def before_batch(self):
if self.every is None: return
if self.training and self.train_iter%self.every==0: self._register()
def after_batch(self):
if self.every is None: return
if self.training and self.train_iter%self.every==0: self._remove()
def after_fit(self):
"Remove the `Hooks`."
if self.remove_end: self._remove()
def _register(self): self.hooks = Hooks(self.modules, self.hook, self.is_forward, self.detach, self.cpu)
def _remove(self):
if getattr(self, 'hooks', None): self.hooks.remove()
def __del__(self): self._remove()
# %% ../../nbs/15_callback.hook.ipynb #5e1d5169
def total_params(m):
"Give the number of parameters of a module and if it's trainable or not"
params = sum([p.numel() for p in m.parameters()])
trains = [p.requires_grad for p in m.parameters()]
return params, (False if len(trains)==0 else trains[0])
# %% ../../nbs/15_callback.hook.ipynb #243d2c45
def layer_info(learn, *xb):
"Return layer infos of `model` on `xb` (only support batch first inputs)"
def _track(m, i, o):
params, trainable, shape = '', '', ''
same = any((isinstance(x[0], torch.Tensor) and x[0].shape[1:] == x[1].shape for x in zip(i, o)))
shape = apply(lambda x: x.shape, o)
if hasattr(m, 'weight'): # non activation layer
params, trainable = total_params(m)
return (type(m).__name__, params, trainable, shape, same)
with Hooks(flatten_model(learn.model), _track) as h:
batch = apply(lambda o:o[:1], xb)
train_only_cbs = [cb for cb in learn.cbs if hasattr(cb, '_only_train_loop')]
with learn.removed_cbs(train_only_cbs), learn.no_logging(), learn as l:
r = l.get_preds(dl=[batch], inner=True, reorder=False)
return h.stored
# %% ../../nbs/15_callback.hook.ipynb #80dd0466
def _get_shapes(o, bs):
inp = o[first(o)] if (isinstance(o, dict)) else o
return ' x '.join([str(bs)] + [str(t) for t in inp[1:]])
def _print_shapes(o, bs):
if isinstance(o, torch.Size): return _get_shapes(o, bs)
elif isinstance(o, tuple): return _get_shapes(o[0], bs)
else: return str([_print_shapes(x, bs) for x in o])
# %% ../../nbs/15_callback.hook.ipynb #8d9fe556
def module_summary(learn, *xb):
"Print a summary of `model` using `xb`"
#Individual parameters wrapped in ParameterModule aren't called through the hooks in `layer_info`,
# thus are not counted inside the summary
#TODO: find a way to have them counted in param number somehow
infos = layer_info(learn, *xb)
n,bs = 76,find_bs(xb)
inp_sz = _print_shapes(apply(lambda x:x.shape, xb), bs)
res = f"{type(learn.model).__name__} (Input shape: {inp_sz})\n"
res += "=" * n + "\n"
res += f"{'Layer (type)':<20} {'Output Shape':<20} {'Param #':<10} {'Trainable':<10}\n"
res += "=" * n
ps,trn_ps,j = 0,0,0
infos = [o for o in infos if o is not None] #see comment in previous cell
prev_sz = None
for typ,np,trn,sz,chnged in infos:
if sz is None: continue
if j == 0:
res += f'\n{"":<20} {_print_shapes(sz, bs)[:19]:<20}' # to avoid a double line at the top
if not chnged and not prev_sz == sz and j > 0: res += "\n" + "_" * n + "\n" + f'{"":<20} {_print_shapes(sz, bs)[:19]:<20}'
j = 1
res += f"\n{typ:<20} {'':<20} {np:<10} {str(trn):<10}"
if np != '':
ps += np
if trn: trn_ps += np
prev_sz = sz
res += "\n" + "_" * n + "\n"
res += f"\nTotal params: {ps:,}\n"
res += f"Total trainable params: {trn_ps:,}\n"
res += f"Total non-trainable params: {ps - trn_ps:,}\n\n"
return PrettyString(res)
# %% ../../nbs/15_callback.hook.ipynb #fc4877af
@patch
def summary(self:Learner):
"Print a summary of the model, optimizer and loss function."
xb = self.dls.train.one_batch()[:getattr(self.dls.train, "n_inp", 1)]
res = module_summary(self, *xb)
res += f"Optimizer used: {self.opt_func}\nLoss function: {self.loss_func}\n\n"
if self.opt is not None:
res += f"Model " + ("unfrozen\n\n" if self.opt.frozen_idx==0 else f"frozen up to parameter group #{self.opt.frozen_idx}\n\n")
res += "Callbacks:\n" + '\n'.join(f" - {cb}" for cb in self.cbs.sorted('order'))
return PrettyString(res)
# %% ../../nbs/15_callback.hook.ipynb #2ee4cbe8
@delegates()
class ActivationStats(HookCallback):
"Callback that record the mean and std of activations."
order=-20
def __init__(self, with_hist=False, **kwargs):
super().__init__(**kwargs)
self.with_hist = with_hist
def before_fit(self):
"Initialize stats."
super().before_fit()
self.stats = L()
def hook(self, m, i, o):
if isinstance(o, tuple): return self.hook_multi_ouput(o)
o = o.float()
res = {'mean': o.mean().item(), 'std': o.std().item(),
'near_zero': (o<=0.05).long().sum().item()/o.numel()}
if self.with_hist: res['hist'] = o.histc(40,0,10)
return res
def hook_multi_ouput(self,o_tuple):
"For outputs of RNN which are [nested] tuples of tensors"
res = []
for o in self._flatten_tuple(o_tuple):
if not(isinstance(o, Tensor)): continue
res.append(self.hook(None, None, o))
return res
def _flatten_tuple(self, o_tuple):
"Recursively flatten a [nested] tuple"
res = []
for it in o_tuple:
if isinstance(it, tuple): res += self._flatten_tuple(it)
else: res += [it]
return tuple(res)
def after_batch(self):
"Take the stored results and puts it in `self.stats`"
if self.training and (self.every is None or self.train_iter%self.every == 0): self.stats.append(self.hooks.stored)
super().after_batch()
def layer_stats(self, idx):
lstats = self.stats.itemgot(idx)
return L(lstats.itemgot(o) for o in ('mean','std','near_zero'))
def hist(self, idx):
res = self.stats.itemgot(idx).itemgot('hist')
return torch.stack(tuple(res)).t().float().log1p()
def color_dim(self, idx, figsize=(10,5), ax=None):
"The 'colorful dimension' plot"
res = self.hist(idx)
if ax is None: ax = subplots(figsize=figsize)[1][0]
ax.imshow(res, origin='lower')
ax.axis('off')
def plot_layer_stats(self, idx):
_,axs = subplots(1, 3, figsize=(12,3))
for o,ax,title in zip(self.layer_stats(idx),axs,('mean','std','% near zero')):
ax.plot(o)
ax.set_title(title)