Preface

Python Machine Learning By Example, Third Edition serves as a comprehensive gateway into the world of machine learning (ML).

With six new chapters, covering topics such as movie recommendation engine development with Naïve Bayes, recognizing faces with support vector machines, predicting stock prices with artificial neural networks, categorizing images of clothing with convolutional neural networks, predicting with sequences using recurring neural networks, and leveraging reinforcement learning for decision making, the book has been considerably updated for the latest enterprise requirements.

At the same time, the book provides actionable insights on the key fundamentals of ML with Python programming. Hayden applies his expertise to demonstrate implementations of algorithms in Python, both from scratch and with libraries such as TensorFlow and Keras.

Each chapter walks through an industry-adopted application. With the help of realistic examples, you will gain an understanding of the mechanics of ML techniques in areas such as exploratory data analysis, feature engineering, classification, regression, clustering, and natural language processing.

By the end of this book, you will have gained a broad picture of the ML ecosystem and will be well-versed in the best practices of applying ML techniques with Python to solve problems.

Who this book is for

If you're a machine learning enthusiast, data analyst, or data engineer who's highly passionate about machine learning and you want to begin working on ML assignments, this book is for you.

Prior knowledge of Python coding is assumed and basic familiarity with statistical concepts will be beneficial, although this is not necessary.

What this book covers

Chapter 1, Getting Started with Machine Learning and Python, will kick off your Python machine learning journey. It will start with what machine learning is, why we need it, and its evolution over the last few decades. It will then discuss typical machine learning tasks and explore several essential techniques of working with data and working with models, in a practical and fun way. You will also set up the software and tools needed for examples and projects in the upcoming chapters.

Chapter 2, Building a Movie Recommendation Engine with Naïve Bayes, will focus on classification, specifically binary classification and Naïve Bayes. The goal of the chapter is to build a movie recommendation system. You will learn the fundamental concepts of classification, and about Naïve Bayes, a simple yet powerful algorithm. It will also demonstrate how to fine-tune a model, which is an important skill for every data science or machine learning practitioner to learn.

Chapter 3, Recognizing Faces with Support Vector Machine, will continue the journey of supervised learning and classification. Specifically, it will focus on multiclass classification and support vector machine classifiers. It will discuss how the support vector machine algorithm searches for a decision boundary in order to separate data from different classes. Also, you will implement the algorithm with scikit-learn, and apply it to solve various real-life problems including face recognition.

Chapter 4, Predicting Online Ad Click-Through with Tree-Based Algorithms, will introduce and explain in depth tree-based algorithms (including decision trees, random forests, and boosted trees) throughout the course of solving the advertising click-through rate problem. You will explore decision trees from the root to the leaves, and work on implementations of tree models from scratch, using scikit-learn and XGBoost. Feature importance, feature selection, and ensemble will be covered alongside.

Chapter 5, Predicting Online Ad Click-Through with Logistic Regression, will be a continuation of the ad click-through prediction project, with a focus on a very scalable classification model—logistic regression. You will explore how logistic regression works, and how to work with large datasets. The chapter will also cover categorical variable encoding, L1 and L2 regularization, feature selection, online learning, and stochastic gradient descent.

Chapter 6, Scaling Up Prediction to Terabyte Click Logs, will be about a more scalable solution to massive ad click prediction, utilizing powerful parallel computing tools including Apache Hadoop and Spark. It will cover the essential concepts of Spark such as installation, RDD, and core programming, as well its ML components. You will work with the entire ad click dataset, build classification models, and perform feature engineering and performance evaluation using Spark.

Chapter 7, Predicting Stock Prices with Regression Algorithms, will focus on several popular regression algorithms, including linear regression, regression tree and regression forest, and support vector regression. It will encourage you to utilize them to tackle a billion (or trillion) dollar problem—stock price prediction. You will practice solving regression problems using scikit-learn and TensorFlow.

Chapter 8, Predicting Stock Prices with Artificial Neural Networks, will introduce and explain in depth neural network models. It will cover the building blocks of neural networks, and important concepts such as activation functions, feedforward, and backpropagation. You will start by building the simplest neural network and go deeper by adding more layers to it. We will implement neural networks from scratch, use TensorFlow and Keras, and train a neural network to predict stock prices.

Chapter 9, Mining the 20 Newsgroups Dataset with Text Analysis Techniques, will start the second step of your learning journey—unsupervised learning. It will explore a natural language processing problem—exploring newsgroups data. You will gain hands-on experience in working with text data, especially how to convert words and phrases into machine-readable values and how to clean up words with little meaning. You will also visualize text data using a dimension reduction technique called t-SNE.

Chapter 10, Discovering Underlying Topics in the Newsgroups Dataset with Clustering and Topic Modeling, will talk about identifying different groups of observations from data in an unsupervised manner. You will cluster the newsgroups data using the K-means algorithm, and detect topics using non-negative matrix factorization and latent Dirichlet allocation. You will be amused by how many interesting themes you are able to mine from the 20 newsgroups dataset!

Chapter 11, Machine Learning Best Practices, will aim to fully prove your learning and get you ready for real-world projects. It includes 21 best practices to follow throughout the entire machine learning workflow.

Chapter 12, Categorizing Images of Clothing with Convolutional Neural Networks, will be about using convolutional neural networks (CNNs), a very powerful modern machine learning model, to classify images of clothing. It will cover the building blocks and architecture of CNNs, and their implementation using TensorFlow and Keras. After exploring the data of clothing images, you will develop CNN models to categorize the images into ten classes, and utilize data augmentation techniques to boost the classifier.

Chapter 13, Making Predictions with Sequences using Recurrent Neural Networks, will start by defining sequential learning, and exploring how recurrent neural networks (RNNs) are well suited for it. You will learn about various types of RNNs and their common applications. You will implement RNNs with TensorFlow, and apply them to solve two interesting sequential learning problems: sentiment analysis on IMDb movie reviews and text auto-generation. Finally, as a bonus section, it will cover the Transformer as a state-of-the-art sequential learning model.

Chapter 14, Making Decisions in Complex Environments with Reinforcement Learning, will be about learning from experience, and interacting with the environment. After exploring the fundamentals of reinforcement learning, you will explore the FrozenLake environment with a simple dynamic programming algorithm. You will learn about Monte Carlo learning and use it for value approximation and control. You will also develop temporal difference algorithms and use Q-learning to solve the taxi problem.

To get the most out of this book

You are expected to have a basic foundation of knowledge of Python, the basic machine learning algorithms, and some basic Python libraries, such as TensorFlow and Keras, in order to create smart cognitive actions for your projects.

Download the example code files

The code bundle for the book is hosted on GitHub at https://github.com/PacktPublishing/Python-Machine-Learning-By-Example-Third-Edition. We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

Download the color images

We also provide a PDF file that has color images of the screenshots/diagrams used in this book. You can download it here: https://static.packt-cdn.com/downloads/9781800209718_ColorImages.pdf.

Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. For example; "Then, we'll load the en_core_web_sm model and parse the sentence using this model."

A block of code is set as follows:

>>> from sklearn import datasets
>>> iris = datasets.load_iris()
>>> X = iris.data[:, 2:4]
>>> y = iris.target

Any command-line input or output is written as follows:

conda install pytorch torchvision -c pytorch

Bold: Indicates a new term, an important word, or words that you see on the screen, for example, in menus or dialog boxes, also appear in the text like this. For example: "A new window will pop up and ask us which collections (the Collections tab in the following screenshot) or corpus (the identifiers in the Corpora tab in the following screenshot) to download and where to keep the data."

Get in touch

Feedback from our readers is always welcome.

General feedback: Email [email protected], and mention the book's title in the subject of your message. If you have questions about any aspect of this book, please email us at [email protected].

Errata: Although we have taken every care to ensure the accuracy of our content, mistakes do happen. If you have found a mistake in this book we would be grateful if you would report this to us. Please visit, http://www.packtpub.com/submit-errata, selecting your book, clicking on the Errata Submission Form link, and entering the details.

Piracy: If you come across any illegal copies of our works in any form on the Internet, we would be grateful if you would provide us with the location address or website name. Please contact us at [email protected] with a link to the material.

If you are interested in becoming an author: If there is a topic that you have expertise in and you are interested in either writing or contributing to a book, please visit http://authors.packtpub.com.

Reviews

Please leave a review. Once you have read and used this book, why not leave a review on the site that you purchased it from? Potential readers can then see and use your unbiased opinion to make purchase decisions, we at Packt can understand what you think about our products, and our authors can see your feedback on their book. Thank you!

For more information about Packt, please visit packtpub.com.