Book Image

Python Feature Engineering Cookbook - Second Edition

By : Soledad Galli
Book Image

Python Feature Engineering Cookbook - Second Edition

By: Soledad Galli

Overview of this book

Feature engineering, the process of transforming variables and creating features, albeit time-consuming, ensures that your machine learning models perform seamlessly. This second edition of Python Feature Engineering Cookbook will take the struggle out of feature engineering by showing you how to use open source Python libraries to accelerate the process via a plethora of practical, hands-on recipes. This updated edition begins by addressing fundamental data challenges such as missing data and categorical values, before moving on to strategies for dealing with skewed distributions and outliers. The concluding chapters show you how to develop new features from various types of data, including text, time series, and relational databases. With the help of numerous open source Python libraries, you'll learn how to implement each feature engineering method in a performant, reproducible, and elegant manner. By the end of this Python book, you will have the tools and expertise needed to confidently build end-to-end and reproducible feature engineering pipelines that can be deployed into production.
Table of Contents (14 chapters)

Creating features with general and cumulative operations

Featuretools uses what are called transform primitives to create features. Transform primitives take one or more columns in a dataset as input and return one or more columns as output. They are applied to a single dataframe.

Featuretools divides its transform primitives into various categories depending on the type of operation they perform or the type of variable they modify. For example, general transform primitives apply mathematical operations, such as the square root, the sine, and the cosine. Cumulative transform primitives create new features by comparing a row’s value to the previous row’s value. For example, the cumulative sum, cumulative mean, and cumulative minimum and maximum values belong to this category, as well as the difference between row values. There is another cumulative transformation that can be applied to datetime variables, which is the time since previous, which determines the time passed...