Book Image

Mastering Machine Learning Algorithms

Book Image

Mastering Machine Learning Algorithms

Overview of this book

Machine learning is a subset of AI that aims to make modern-day computer systems smarter and more intelligent. The real power of machine learning resides in its algorithms, which make even the most difficult things capable of being handled by machines. However, with the advancement in the technology and requirements of data, machines will have to be smarter than they are today to meet the overwhelming data needs; mastering these algorithms and using them optimally is the need of the hour. Mastering Machine Learning Algorithms is your complete guide to quickly getting to grips with popular machine learning algorithms. You will be introduced to the most widely used algorithms in supervised, unsupervised, and semi-supervised machine learning, and will learn how to use them in the best possible manner. Ranging from Bayesian models to the MCMC algorithm to Hidden Markov models, this book will teach you how to extract features from your dataset and perform dimensionality reduction by making use of Python-based libraries such as scikit-learn v0.19.1. You will also learn how to use Keras and TensorFlow 1.x to train effective neural networks. If you are looking for a single resource to study, implement, and solve end-to-end machine learning problems and use-cases, this is the book you need.
Table of Contents (22 chapters)
Title Page
Dedication
Packt Upsell
Contributors
Preface
13
Deep Belief Networks
Index

Summary


In this chapter, we presented the MRF as the underlying structure of an RBM. An MRF is represented as an undirected graph whose vertices are random variables. In particular, for our purposes, we considered MRFs whose joint probability can be expressed as a product of the positive functions of each random variable. The most common distribution, based on an exponential, is called the Gibbs (or Boltzmann) distribution and it is particularly suitable for our problems because the logarithm cancels the exponential, yielding simpler expressions.

An RBM is a simple bipartite, undirected graph, made up of visible and latent variables, with connections only between different groups. The goal of this model is to learn a probability distribution, thanks to the presence of hidden units that can model the unknown relationships. Unfortunately, the log-likelihood, although very simple, cannot be easily optimized because the normalization term requires summing over all the input values. For this reason...