Introduction to Machine Learning

Artificial intelligence (AI) techniques are currently being widely used in microbiome research to study the microbiota and its role in health and disease. It is generally known that AI techniques include machine learning and deep learning, with deep learning being a subset of machine learning techniques. In addition to the Summary, there are eight sections in this chapter. Section 1.1 describes statistical learning and describes six types of machine learning algorithms: (1) supervised learning methods for classification and regression, (2) unsupervised learning methods for clustering and dimensionality reduction, (3) ensemble learning methods, (4) artificial neural networks and deep learning, (5) semi-supervised learning, and (6) reinforcement learning. Sections 1.2 to 1.7 introduce these six types of machine learning algorithms, respectively. Section 1.8 provides general remarks on machine learning, including (1) supervised learning versus unsupervised learning, (2) deep learning versus ensemble learning, and (3) deep learning versus unsupervised learning.