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)

Capping outliers using quantiles

When capping outliers, we clip the variable extreme values to a certain maximum or minimum value determined by some statistical parameter. A typical strategy involves setting outliers to a specified percentile. For example, we can set all data below the 5th percentile to the value at the 5th percentile and all data greater than the 95th percentile to the value at the 95th percentile. In this recipe, we will cap variables at arbitrary values determined by the percentiles using pandas and Feature-engine.

How to do it...

Let’s first import the Python libraries and load the data:

  1. Import the required Python libraries:
    import pandas as pd
    from sklearn.datasets import load_breast_cancer
    from sklearn.model_selection import train_test_split
    from feature_engine.outliers import Winsorizer
  2. Let’s load the Breast Cancer dataset from scikit-learn:
    breast_cancer = load_breast_cancer()
    X = pd.DataFrame(
        breast_cancer...