book

Fundamentals of Deep Learning, 2nd Edition

by Nithin Buduma, Nikhil Buduma, Joe Papa

May 2022

Intermediate to advanced

387 pages

11h 47m

English

O'Reilly Media, Inc.

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Prerequisites and ObjectivesHow Is This Book Organized?Conventions Used in This BookUsing Code ExamplesO’Reilly Online LearningHow to Contact UsAcknowledgementsNithin and NikhilJoe
Data Structures and OperationsMatrix OperationsVector OperationsMatrix-Vector MultiplicationThe Fundamental SpacesThe Column SpaceThe Null SpaceEigenvectors and EigenvaluesSummary
Events and ProbabilityConditional ProbabilityRandom VariablesExpectationVarianceBayes’ TheoremEntropy, Cross Entropy, and KL DivergenceContinuous Probability DistributionsSummary
Building Intelligent MachinesThe Limits of Traditional Computer ProgramsThe Mechanics of Machine LearningThe NeuronExpressing Linear Perceptrons as NeuronsFeed-Forward Neural NetworksLinear Neurons and Their LimitationsSigmoid, Tanh, and ReLU NeuronsSoftmax Output LayersSummary
The Fast-Food ProblemGradient DescentThe Delta Rule and Learning RatesGradient Descent with Sigmoidal NeuronsThe Backpropagation AlgorithmStochastic and Minibatch Gradient DescentTest Sets, Validation Sets, and OverfittingPreventing Overfitting in Deep Neural NetworksSummary
Introduction to PyTorchInstalling PyTorchPyTorch TensorsTensor InitTensor AttributesTensor OperationsGradients in PyTorchThe PyTorch nn ModulePyTorch Datasets and DataloadersBuilding the MNIST Classifier in PyTorchSummary
The Challenges with Gradient DescentLocal Minima in the Error Surfaces of Deep NetworksModel IdentifiabilityHow Pesky Are Spurious Local Minima in Deep Networks?Flat Regions in the Error SurfaceWhen the Gradient Points in the Wrong DirectionMomentum-Based OptimizationA Brief View of Second-Order MethodsLearning Rate AdaptationAdaGrad—Accumulating Historical GradientsRMSProp—Exponentially Weighted Moving Average of GradientsAdam—Combining Momentum and RMSPropThe Philosophy Behind Optimizer SelectionSummary
Neurons in Human VisionThe Shortcomings of Feature SelectionVanilla Deep Neural Networks Don’t ScaleFilters and Feature MapsFull Description of the Convolutional LayerMax PoolingFull Architectural Description of Convolution NetworksClosing the Loop on MNIST with Convolutional NetworksImage Preprocessing Pipelines Enable More Robust ModelsAccelerating Training with Batch NormalizationGroup Normalization for Memory Constrained Learning TasksBuilding a Convolutional Network for CIFAR-10Visualizing Learning in Convolutional NetworksResidual Learning and Skip Connections for Very Deep NetworksBuilding a Residual Network with Superhuman VisionLeveraging Convolutional Filters to Replicate Artistic StylesLearning Convolutional Filters for Other Problem DomainsSummary
Learning Lower-Dimensional RepresentationsPrincipal Component AnalysisMotivating the Autoencoder ArchitectureImplementing an Autoencoder in PyTorchDenoising to Force Robust RepresentationsSparsity in AutoencodersWhen Context Is More Informative than the Input VectorThe Word2Vec FrameworkImplementing the Skip-Gram ArchitectureSummary
Analyzing Variable-Length InputsTackling seq2seq with Neural N-GramsImplementing a Part-of-Speech TaggerDependency Parsing and SyntaxNetBeam Search and Global NormalizationA Case for Stateful Deep Learning ModelsRecurrent Neural NetworksThe Challenges with Vanishing GradientsLong Short-Term Memory UnitsPyTorch Primitives for RNN ModelsImplementing a Sentiment Analysis ModelSolving seq2seq Tasks with Recurrent Neural NetworksAugmenting Recurrent Networks with AttentionDissecting a Neural Translation NetworkSelf-Attention and TransformersSummary

Generative Adversarial NetworksVariational AutoencodersImplementing a VAEScore-Based Generative ModelsDenoising Autoencoders and Score MatchingSummary
OverviewDecision Trees and Tree-Based AlgorithmsLinear RegressionMethods for Evaluating Feature ImportancePermutation Feature ImportancePartial Dependence PlotsExtractive RationalizationLIMESHAPSummary
Neural Turing MachinesAttention-Based Memory AccessNTM Memory Addressing MechanismsDifferentiable Neural ComputersInterference-Free Writing in DNCsDNC Memory ReuseTemporal Linking of DNC WritesUnderstanding the DNC Read HeadThe DNC Controller NetworkVisualizing the DNC in ActionImplementing the DNC in PyTorchTeaching a DNC to Read and ComprehendSummary
Deep Reinforcement Learning Masters Atari GamesWhat Is Reinforcement Learning?Markov Decision ProcessesPolicyFuture ReturnDiscounted Future ReturnExplore Versus Exploit ϵ -GreedyAnnealed ϵ -GreedyPolicy Versus Value LearningPole-Cart with Policy GradientsOpenAI GymCreating an AgentBuilding the Model and OptimizerSampling ActionsKeeping Track of HistoryPolicy Gradient Main FunctionPGAgent Performance on Pole-CartTrust-Region Policy OptimizationProximal Policy OptimizationQ-Learning and Deep Q-NetworksThe Bellman EquationIssues with Value IterationApproximating the Q-FunctionDeep Q-NetworkTraining DQNLearning StabilityTarget Q-NetworkExperience ReplayFrom Q-Function to PolicyDQN and the Markov AssumptionDQN’s Solution to the Markov AssumptionPlaying Breakout with DQNBuilding Our ArchitectureStacking FramesSetting Up Training OperationsUpdating Our Target Q-NetworkImplementing Experience ReplayDQN Main LoopDQNAgent Results on BreakoutImproving and Moving Beyond DQNDeep Recurrent Q-NetworksAsynchronous Advantage Actor-Critic AgentUNsupervised REinforcement and Auxiliary LearningSummary

Content preview from Fundamentals of Deep Learning, 2nd Edition

Chapter 5. Implementing Neural Networks in PyTorch

Introduction to PyTorch

In this chapter, you will learn the basics of PyTorch, one of the most popular deep learning frameworks in use today. PyTorch was introduced by Facebook’s AI Research Lab in 2016 and gained users rapidly, both in industry and in research, through the following years. One reason for PyTorch’s widespread adoption was its intuitive, Pythonic feel, which fit naturally into the preexisting workstreams and coding paradigms followed by deep learning practitioners.

In particular, this chapter will discuss the data structures utilized by PyTorch, how to define neural models in PyTorch, and how to connect data with models for training and testing. Finally, we implement a practical example in PyTorch—a classifier for the MNIST digits dataset, complete with code for training and testing the classifier.

Installing PyTorch

Installing a CPU-compatible version of PyTorch is relatively simple. The PyTorch docs recommend using conda, a package management system. Within conda, you can create multiple environments, where an environment is a context that encapsulates all of your package installs. Access to a package does not transfer across environments—this allows the user to have a clean separation between different contexts by downloading packages within individual environments. We recommend that you create a conda environment for deep learning purposes that you can switch into whenever necessary. We refer you to the ...