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Python Feature Engineering Cookbook

You're reading from   Python Feature Engineering Cookbook Over 70 recipes for creating, engineering, and transforming features to build machine learning models

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Product type Paperback
Published in Jan 2020
Publisher Packt
ISBN-13 9781789806311
Length 372 pages
Edition 1st Edition
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Author (1):
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Soledad Galli Soledad Galli
Author Profile Icon Soledad Galli
Soledad Galli
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Table of Contents (13) Chapters Close

Preface 1. Foreseeing Variable Problems When Building ML Models 2. Imputing Missing Data FREE CHAPTER 3. Encoding Categorical Variables 4. Transforming Numerical Variables 5. Performing Variable Discretization 6. Working with Outliers 7. Deriving Features from Dates and Time Variables 8. Performing Feature Scaling 9. Applying Mathematical Computations to Features 10. Creating Features with Transactional and Time Series Data 11. Extracting Features from Text Variables 12. Other Books You May Enjoy

Cleaning and stemming text variables

We mentioned previously that some variables in our dataset can be created based on free text fields, which are manually completed by users. People have different writing styles, and we use a variety of punctuation marks, capitalization patterns, and verb conjugation to convey the content, as well as the emotion around it. We can extract information from text without taking the trouble to read it by creating statistical parameters that summarize the text complexity, keywords, and relevance of words in a document. We discussed these methods in the preceding recipes of this chapter. Yet, to derive these statistics and aggregated features, we should clean the text variables first.

Text cleaning or text preprocessing involves punctuation removal, the elimination of stop words, character case setting, and word stemming. Punctuation removal consists...

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