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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

Aggregating transactions with mathematical operations

Previously, we mentioned that we can aggregate information from historical data points into single observations like the maximum amount spent on a transaction, the total number of transactions, or the mean value of all transactions, to name a few examples. These aggregations are made with basic mathematical operations, such as the maximum, mean, and count. As you can see, mathematical operations are a simple yet powerful way to obtain a summarized view of historical data.

In this recipe, we will create a flattened dataset by aggregating multiple transactions using common mathematical operations. We will use pandas to do this.

In a flattened dataset, we remove the time-dimension from the transaction data or time series to obtain a single observation per entity.
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