Artificial Neural Networks and Deep Learning

This chapter focuses on artificial neural networks (ANNs) and deep learning. In addition to the Summary, there are four sections. Section 13.1 introduces ANNs, including the structure of neural networks, feed-forward neural networks, activation functions, and fitting a neural network. Section 13.2 introduces deep learning, including a brief history of neural networks, commonly used ANNs, and deep learning methods. Section 13.3 illustrates fitting a neural network with microbiome data using the nnet package. Section 13.4 provides some remarks on ANNs, including their general characteristics, advantages, and disadvantages, as well as the advantages and disadvantages of the backpropagation algorithm.