Book Image

Mastering Machine Learning Algorithms. - Second Edition

By : Giuseppe Bonaccorso
Book Image

Mastering Machine Learning Algorithms. - Second Edition

By: Giuseppe Bonaccorso

Overview of this book

Mastering Machine Learning Algorithms, Second Edition helps you harness the real power of machine learning algorithms in order to implement smarter ways of meeting today's overwhelming data needs. This newly updated and revised guide will help you master algorithms used widely in semi-supervised learning, reinforcement learning, supervised learning, and unsupervised learning domains. You will use all the modern libraries from the Python ecosystem – including NumPy and Keras – to extract features from varied complexities of data. Ranging from Bayesian models to the Markov chain Monte Carlo algorithm to Hidden Markov models, this machine learning book teaches you how to extract features from your dataset, perform complex dimensionality reduction, and train supervised and semi-supervised models by making use of Python-based libraries such as scikit-learn. You will also discover practical applications for complex techniques such as maximum likelihood estimation, Hebbian learning, and ensemble learning, and how to use TensorFlow 2.x to train effective deep neural networks. By the end of this book, you will be ready to implement and solve end-to-end machine learning problems and use case scenarios.
Table of Contents (28 chapters)
26
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27
Index

Rubner-Tavan's network

In Chapter 13, Component Analysis and Dimensionality Reduction, we mentioned that any algorithm that decorrelates the input covariance matrix is performing a PCA without dimensionality reduction. Starting from this approach, Rubner and Tavan (in the paper Rubner J., Tavan P., A Self-Organizing Network for Principal-Components Analysis, Europhysics, Letters, 10(7), 1989) proposed a neural model whose goal is decorrelating the output components to force the consequent decorrelation of the output covariance matrix (in lower-dimensional subspace). Assuming a zero-centered dataset and E[y] = 0, the output covariance matrix for m principal components is as follows:

Hence, it's possible to achieve an approximate decorrelation, forcing the terms to become close to zero.

The main difference with a standard approach (such as whitening or vanilla PCA) is that this procedure is local, while all the standard methods operate globally, directly with...