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)

Extracting features from dates with pandas

datetime variables can take dates, time, or dates and time as values. They are not used in their raw format to build machine learning algorithms. Instead, we create additional features from them, and we can enrich the dataset dramatically by extracting information from the date and time.

The pandas Python library contains a lot of capabilities for working with dates and time. pandas dt is the accessor object to the datetime properties of a pandas Series. To access the pandas dt functionality, the variables should be cast in a data type that supports these operations, such as datetime or timedelta.

Tip

Often, the datetime variables are cast as objects, particularly when the data is loaded from a CSV file. Therefore, to extract the date and time features that we will discuss throughout this chapter, it is necessary to recast the variables as datetime.

In this recipe, we will learn how to extract features from dates by utilizing pandas...