Book Image

Neural Networks with R

By : Balaji Venkateswaran, Giuseppe Ciaburro
Book Image

Neural Networks with R

By: Balaji Venkateswaran, Giuseppe Ciaburro

Overview of this book

Neural networks are one of the most fascinating machine learning models for solving complex computational problems efficiently. Neural networks are used to solve wide range of problems in different areas of AI and machine learning. This book explains the niche aspects of neural networking and provides you with foundation to get started with advanced topics. The book begins with neural network design using the neural net package, then you’ll build a solid foundation knowledge of how a neural network learns from data, and the principles behind it. This book covers various types of neural network including recurrent neural networks and convoluted neural networks. You will not only learn how to train neural networks, but will also explore generalization of these networks. Later we will delve into combining different neural network models and work with the real-world use cases. By the end of this book, you will learn to implement neural network models in your applications with the help of practical examples in the book.

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Table of Contents (14 chapters)
Title Page
Title Page
Credits
Credits
About the Authors
About the Authors
About the Reviewer
About the Reviewer
www.PacktPub.com
www.PacktPub.com
Customer Feedback
Customer Feedback
Preface
Preface
Free Chapter
1
Neural Network and Artificial Intelligence Concepts
Neural Network and Artificial Intelligence Concepts
Introduction
Inspiration for neural networks
How do neural networks work?
Layered approach
Weights and biases
Training neural networks
Epoch
Activation functions
Different activation functions
Which activation functions to use?
Perceptron and multilayer architectures
Forward and backpropagation
Step-by-step illustration of a neuralnet and an activation function
Feed-forward and feedback networks
Gradient descent
Taxonomy of neural networks
Simple example using R neural net library - neuralnet()
Implementation using nnet() library
Deep learning
Pros and cons of neural networks
Best practices in neural network implementations
Quick note on GPU processing
Summary
2
Learning Process in Neural Networks
Learning Process in Neural Networks
What is machine learning?
Supervised learning
Unsupervised learning
Reinforcement learning
Training and testing the model
The data cycle
Evaluation metrics
Learning in neural networks
Back to backpropagation
Neural network learning algorithm optimization
Supervised learning in neural networks
Unsupervised learning in neural networks 
Summary
3
Deep Learning Using Multilayer Neural Networks
Deep Learning Using Multilayer Neural Networks
Introduction of DNNs
R for DNNs
Multilayer neural networks with neuralnet
Training and modeling a DNN using H2O
Deep autoencoders using H2O
Summary
4
Perceptron Neural Network Modeling – Basic Models
Perceptron Neural Network Modeling – Basic Models
Perceptrons and their applications
Simple perceptron – a linear separable classifier
Linear separation
The perceptron function in R
Multi-Layer Perceptron
MLP R implementation using RSNNS
Summary
5
Training and Visualizing a Neural Network in R
Training and Visualizing a Neural Network in R
Data fitting with neural network
Classifing breast cancer with a neural network
Early stopping in neural network training
Avoiding overfitting in the model
Generalization of neural networks
Scaling of data in neural network models
Ensemble predictions using neural networks
Summary
6
Recurrent and Convolutional Neural Networks
Recurrent and Convolutional Neural Networks
Recurrent Neural Network
The rnn package in R
LSTM model
Convolutional Neural Networks
Common CNN architecture - LeNet
Humidity forecast using RNN
Summary
7
Use Cases of Neural Networks – Advanced Topics
Use Cases of Neural Networks – Advanced Topics
TensorFlow integration with R
Keras integration with R
MNIST HWR using R
LSTM using the iris dataset
Working with autoencoders
PCA using H2O
Autoencoders using H2O
Breast cancer detection using darch
Summary

Activation functions

The abstraction of the processing of neural networks is mainly achieved through the activation functions. An activation function is a mathematical function which converts the input to an output, and adds the magic of neural network processing. Without activation functions, the working of neural networks will be like linear functions. A linear function is one where the output is directly proportional to input, for example:

 

A linear function is a polynomial of one degree. Simply, it is a straight line without any curves.

However, most of the problems the neural networks try to solve are nonlinear and complex in nature. To achieve the nonlinearity, the activation functions are used. Nonlinear functions are high degree polynomial functions, for example:

 

The graph of a nonlinear function is curved and adds the complexity factor.

Activation functions give the nonlinearity property to neural networks and make them true universal function approximators.

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