Book Image

Machine Learning for Imbalanced Data

By : Kumar Abhishek, Dr. Mounir Abdelaziz
Book Image

Machine Learning for Imbalanced Data

By: Kumar Abhishek, Dr. Mounir Abdelaziz

Overview of this book

As machine learning practitioners, we often encounter imbalanced datasets in which one class has considerably fewer instances than the other. Many machine learning algorithms assume an equilibrium between majority and minority classes, leading to suboptimal performance on imbalanced data. This comprehensive guide helps you address this class imbalance to significantly improve model performance. Machine Learning for Imbalanced Data begins by introducing you to the challenges posed by imbalanced datasets and the importance of addressing these issues. It then guides you through techniques that enhance the performance of classical machine learning models when using imbalanced data, including various sampling and cost-sensitive learning methods. As you progress, you’ll delve into similar and more advanced techniques for deep learning models, employing PyTorch as the primary framework. Throughout the book, hands-on examples will provide working and reproducible code that’ll demonstrate the practical implementation of each technique. By the end of this book, you’ll be adept at identifying and addressing class imbalances and confidently applying various techniques, including sampling, cost-sensitive techniques, and threshold adjustment, while using traditional machine learning or deep learning models.
Table of Contents (15 chapters)

Undersampling Methods

Sometimes, you have so much data that adding more data by oversampling only makes things worse. Don’t worry, as we have a strategy for those situations as well. It’s called undersampling, or downsampling. In this chapter, you will learn about the concept of undersampling, including when to use it and the various techniques to perform it. You will also see how to use these techniques via the imbalanced-learn library APIs and compare their performance with some classical machine learning models.

In this chapter, we will cover the following topics:

  • Introducing undersampling
  • When to avoid undersampling in the majority class
  • Removing examples uniformly
  • Strategies for removing noisy observations
  • Strategies for removing easy observations

By the end of this chapter, you’ll have mastered various undersampling techniques for imbalanced datasets and will be able to confidently apply them with the imbalanced-learn library...