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

Independent component analysis


We have seen that the factors extracted by a PCA are decorrelated, but not independent. A classic example is the cocktail party: we have a recording of many overlapped voices and we would like to separate them. Every single voice can be modeled as a random process and it's possible to assume that they are statistically independent (this means that the joint probability can be factorized using the marginal probabilities of each source). Using FA or PCA, we are able to find uncorrelated factors, but there's no way to assess whether they are also independent (normally, they aren't). In this section, we are going to study a model that is able to produce sparse representations (when the dictionary isn't under-complete) with a set of statistically independent components.

Let's assume we have a zero-centered and whitened dataset X sampled from N(0, I) and noiseless linear transformation:

In this case, the prior over, z, is modeled as a product of independent variables...