Book Image

Hands-On Machine Learning with scikit-learn and Scientific Python Toolkits

By : Tarek Amr
Book Image

Hands-On Machine Learning with scikit-learn and Scientific Python Toolkits

By: Tarek Amr

Overview of this book

Machine learning is applied everywhere, from business to research and academia, while scikit-learn is a versatile library that is popular among machine learning practitioners. This book serves as a practical guide for anyone looking to provide hands-on machine learning solutions with scikit-learn and Python toolkits. The book begins with an explanation of machine learning concepts and fundamentals, and strikes a balance between theoretical concepts and their applications. Each chapter covers a different set of algorithms, and shows you how to use them to solve real-life problems. You’ll also learn about various key supervised and unsupervised machine learning algorithms using practical examples. Whether it is an instance-based learning algorithm, Bayesian estimation, a deep neural network, a tree-based ensemble, or a recommendation system, you’ll gain a thorough understanding of its theory and learn when to apply it. As you advance, you’ll learn how to deal with unlabeled data and when to use different clustering and anomaly detection algorithms. By the end of this machine learning book, you’ll have learned how to take a data-driven approach to provide end-to-end machine learning solutions. You’ll also have discovered how to formulate the problem at hand, prepare required data, and evaluate and deploy models in production.
Table of Contents (18 chapters)
1
Section 1: Supervised Learning
8
Section 2: Advanced Supervised Learning
13
Section 3: Unsupervised Learning and More

Understanding Naive Bayes

The Naive Bayes classifier is commonly used in classifying textual data. In the following sections, we are going to see its different flavors and learn how to configure their parameters. But first, to understand the Naive Bayes classifier, we need to first go through Thomas Bayes' theorem, which he published in the 18th century.

The Bayes rule

When talking about classifiers, we can describe the probability of a certain sample belonging to a certain class using conditional probability, P(y|x). This is the probability of a sample belonging to class y given its features, x. The pipe sign (|) is what we use to refer to conditional probability, that is, y given x. The Bayes rule is capable of expressing this conditional probability in terms of P(x|y), P(x), and P(y), using the following formula:

Usually, we ignore the denominator part of the equation and convert it into a proportion as follows:

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