Book Image

Python Machine Learning By Example - Second Edition

By : Yuxi (Hayden) Liu
Book Image

Python Machine Learning By Example - Second Edition

By: Yuxi (Hayden) Liu

Overview of this book

The surge in interest in machine learning (ML) is due to the fact that it revolutionizes automation by learning patterns in data and using them to make predictions and decisions. If you’re interested in ML, this book will serve as your entry point to ML. Python Machine Learning By Example begins with an introduction to important ML concepts and implementations using Python libraries. Each chapter of the book walks you through an industry adopted application. You’ll implement ML techniques in areas such as exploratory data analysis, feature engineering, and natural language processing (NLP) in a clear and easy-to-follow way. With the help of this extended and updated edition, you’ll understand how to tackle data-driven problems and implement your solutions with the powerful yet simple Python language and popular Python packages and tools such as TensorFlow, scikit-learn, gensim, and Keras. To aid your understanding of popular ML algorithms, the book covers interesting and easy-to-follow examples such as news topic modeling and classification, spam email detection, stock price forecasting, and more. By the end of the book, you’ll have put together a broad picture of the ML ecosystem and will be well-versed with the best practices of applying ML techniques to make the most out of new opportunities.
Table of Contents (15 chapters)
Free Chapter
1
Section 1: Fundamentals of Machine Learning
3
Section 2: Practical Python Machine Learning By Example
12
Section 3: Python Machine Learning Best Practices

Ensembling decision trees – random forest

The ensemble technique bagging (which stands for bootstrap aggregating), which we briefly mentioned in Chapter 1, Getting Started with Machine Learning and Python, can effectively overcome overfitting. To recap, different sets of training samples are randomly drawn with replacements from the original training data; each resulting set is used to fit an individual classification model. The results of these separately trained models are then combined together through a majority vote to make the final decision.

Tree bagging, described in the preceding section, reduces the high variance that a decision tree model suffers from and hence, in general, performs better than a single tree. However, in some cases, where one or more features are strong indicators, individual trees are constructed largely based on these features and as a result...