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

Ensemble learning fundamentals


The main concept behind ensemble learning is the distinction between strong and weak learners. In particular, a strong learner is a classifier or a regressor which has enough capacity to reach the highest potential accuracy, minimizing both bias and variance (thus achieving also a satisfactory level of generalization). More formally, if we consider a parametrized binary classifier f(x; θ), we define it as a strong learner if the following is true:

This expression can appear cryptic; however, it's very easy to understand. It simply expresses the concept that a strong learner is theoretically able to achieve any non-null probability of misclassification with a probability greater than or equal to 0.5 (that is, the threshold for a binary random guess). All the models normally employed in Machine Learning tasks are normally strong learners, even if their domain can be limited (for example, a logistic regression cannot solve non-linear problems). On the other hand...