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 from a Time Series with tsfresh

Throughout this book, we’ve discussed feature engineering methods and tools suitable for tabular data and relational datasets. In this chapter, we will focus on time series data. A time series is a sequence of observations taken sequentially over time. Examples of time series are energy generation and demand, temperature, air pollutant concentration, stock prices, and sales revenue. Each of these examples constitutes a variable, and their values change over time.

The availability of cheap sensors that can measure motion, movement, humidity, or temperature, among several other things, has dramatically increased the availability of temporally annotated data. These time series can then be used in classification tasks. For example, based on the electricity fingerprint of a household at a given time interval, we can infer whether a certain appliance was being used. Based on the signal of an ultrasound sensor, we can determine the...