Daniel Voigt Godoy - Deep Learning with PyTorch Step-by-Step A Beginner’s Guide-leanpub
if callable(self.clipping): 1self.clipping()1# Step 4 - Updates parametersself.optimizer.step()self.optimizer.zero_grad()# Returns the lossreturn loss.item()# Returns the function that will be called inside the train loopreturn perform_train_step_fnsetattr(StepByStep, 'set_clip_grad_value', set_clip_grad_value)setattr(StepByStep, 'set_clip_grad_norm', set_clip_grad_norm)setattr(StepByStep, 'remove_clip', remove_clip)setattr(StepByStep, '_make_train_step_fn', _make_train_step_fn)1 Gradient clipping after computing gradients and before updating parametersThe gradient clipping methods above work just fine for most models, but they areof little use for recurrent neural networks (we’ll discuss them in Chapter 8), whichrequire gradients to be clipped during backpropagation. Fortunately, we can usethe backward hooks code to accomplish that:Vanishing and Exploding Gradients | 579
StepByStep Methoddef set_clip_backprop(self, clip_value):if self.clipping is None:self.clipping = []for p in self.model.parameters():if p.requires_grad:func = lambda grad: torch.clamp(grad,-clip_value,clip_value)handle = p.register_hook(func)self.clipping.append(handle)def remove_clip(self):if isinstance(self.clipping, list):for handle in self.clipping:handle.remove()self.clipping = Nonesetattr(StepByStep, 'set_clip_backprop', set_clip_backprop)setattr(StepByStep, 'remove_clip', remove_clip)The method above will attach hooks to all parameters of the model and performgradient clipping on the fly. We also adjusted the remove_clip() method to removeany handles associated with the hooks.Model Configuration & TrainingLet’s use the method below to initialize the weights so we can reset theparameters of our model that had its gradients exploded:Weight Initialization1 def weights_init(m):2 if isinstance(m, nn.Linear):3 nn.init.kaiming_uniform_(m.weight, nonlinearity='relu')4 if m.bias is not None:5 nn.init.zeros_(m.bias)580 | Extra Chapter: Vanishing and Exploding Gradients
- Page 554 and 555: • reduce the number of output cha
- Page 556 and 557: The constructor method defines the
- Page 558 and 559: Does it sound familiar? That’s wh
- Page 560 and 561: and w to represent these parameters
- Page 562 and 563: A mini-batch of size 64 is small en
- Page 564 and 565: normed1 = batch_normalizer(batch1[0
- Page 566 and 567: OutputOrderedDict([('running_mean',
- Page 568 and 569: OutputOrderedDict([('running_mean',
- Page 570 and 571: batch_normalizer = nn.BatchNorm2d(n
- Page 572 and 573: torch.manual_seed(23)dummy_points =
- Page 574 and 575: np.concatenate([dummy_points[:5].nu
- Page 576 and 577: Another advantage of these shortcut
- Page 578 and 579: It should be pretty clear, except f
- Page 580 and 581: Data Preparation1 # ImageNet statis
- Page 582 and 583: Data Preparation — Preprocessing1
- Page 584 and 585: • freezing the layers of the mode
- Page 586 and 587: Extra ChapterVanishing and Explodin
- Page 588 and 589: discussing it, let me illustrate it
- Page 590 and 591: Model Configuration (2)1 loss_fn =
- Page 592 and 593: weights. If done properly, the init
- Page 594 and 595: just did), or, if you are training
- Page 596 and 597: Figure E.3 - The effect of batch no
- Page 598 and 599: Model Configuration1 torch.manual_s
- Page 600 and 601: torch.manual_seed(42)parm = nn.Para
- Page 602 and 603: (and only if) the norm exceeds the
- Page 606 and 607: Moreover, let’s use a ten times h
- Page 608 and 609: Clipping with HooksFirst, we reset
- Page 610 and 611: • visualizing the difference betw
- Page 612 and 613: Chapter 8SequencesSpoilersIn this c
- Page 614 and 615: Before shuffling, the pixels were o
- Page 616 and 617: And then let’s visualize the firs
- Page 618 and 619: sequence so far, and a data point f
- Page 620 and 621: Considering this, the not "unrolled
- Page 622 and 623: linear_input = nn.Linear(n_features
- Page 624 and 625: Outputtensor([[0.3924, 0.8146]], gr
- Page 626 and 627: Now we’re talking! The last hidde
- Page 628 and 629: Let’s take a look at the RNN’s
- Page 630 and 631: ◦ The initial hidden state, which
- Page 632 and 633: batch_first argument to True so we
- Page 634 and 635: OutputOrderedDict([('weight_ih_l0',
- Page 636 and 637: out, hidden = rnn_stacked(x)out, hi
- Page 638 and 639: _l0_reverse).Once again, let’s cr
- Page 640 and 641: For bidirectional RNNs, the last el
- Page 642 and 643: Model Configuration1 class SquareMo
- Page 644 and 645: StepByStep.loader_apply(test_loader
- Page 646 and 647: Figure 8.14 - Final hidden states f
- Page 648 and 649: Figure 8.16 - Transforming the hidd
- Page 650 and 651: Since the RNN cell has both of them
- Page 652 and 653: Every gate worthy of its name will
if callable(self.clipping): 1
self.clipping()
1
# Step 4 - Updates parameters
self.optimizer.step()
self.optimizer.zero_grad()
# Returns the loss
return loss.item()
# Returns the function that will be called inside the train loop
return perform_train_step_fn
setattr(StepByStep, 'set_clip_grad_value', set_clip_grad_value)
setattr(StepByStep, 'set_clip_grad_norm', set_clip_grad_norm)
setattr(StepByStep, 'remove_clip', remove_clip)
setattr(StepByStep, '_make_train_step_fn', _make_train_step_fn)
1 Gradient clipping after computing gradients and before updating parameters
The gradient clipping methods above work just fine for most models, but they are
of little use for recurrent neural networks (we’ll discuss them in Chapter 8), which
require gradients to be clipped during backpropagation. Fortunately, we can use
the backward hooks code to accomplish that:
Vanishing and Exploding Gradients | 579