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)

Introducing undersampling

Two households, both alike in dignity,

In fair Verona, where we lay our scene,

From ancient grudge break to new mutiny,

Where civil blood makes civil hands unclean.

– Opening lines of Romeo and Juliet, by Shakespeare

Let’s look at a scenario inspired by Shakespeare’s play Romeo and Juliet. Imagine a town with two warring communities (viz., the Montagues and Capulets). They have been enemies for generations. The Montagues are in the minority and the Capulets are in the majority in the town. The Montagues are super rich and powerful. The Capulets are not that well off. This creates a complex situation in the town. There are regular riots in the town because of this rivalry. One day, the Montagues win the king’s favor and conspire to eliminate some Capulets to bring their numbers down. The idea is that if fewer Capulets are in the town, the Montagues will no longer be in the minority. The king agrees to the plan as he...