Book Image

Hands-On Machine Learning with scikit-learn and Scientific Python Toolkits

By : Tarek Amr
Book Image

Hands-On Machine Learning with scikit-learn and Scientific Python Toolkits

By: Tarek Amr

Overview of this book

Machine learning is applied everywhere, from business to research and academia, while scikit-learn is a versatile library that is popular among machine learning practitioners. This book serves as a practical guide for anyone looking to provide hands-on machine learning solutions with scikit-learn and Python toolkits. The book begins with an explanation of machine learning concepts and fundamentals, and strikes a balance between theoretical concepts and their applications. Each chapter covers a different set of algorithms, and shows you how to use them to solve real-life problems. You’ll also learn about various key supervised and unsupervised machine learning algorithms using practical examples. Whether it is an instance-based learning algorithm, Bayesian estimation, a deep neural network, a tree-based ensemble, or a recommendation system, you’ll gain a thorough understanding of its theory and learn when to apply it. As you advance, you’ll learn how to deal with unlabeled data and when to use different clustering and anomaly detection algorithms. By the end of this machine learning book, you’ll have learned how to take a data-driven approach to provide end-to-end machine learning solutions. You’ll also have discovered how to formulate the problem at hand, prepare required data, and evaluate and deploy models in production.
Table of Contents (18 chapters)
1
Section 1: Supervised Learning
8
Section 2: Advanced Supervised Learning
13
Section 3: Unsupervised Learning and More

Using KNN-inspired algorithms

We have encountered enough variants of the KNNalgorithm for it be our first choice for solving the recommendation problem. In the user-item rating matrix from the previous section, each row represents a user and each column represents an item. Thus, similar rows represent users who have similar tastes and identical columns represent items liked by the same users. Therefore, if we want to estimate the rating (ru,i),given by the user (u) to the item (i), we can get the KNNs to the user (u), find their ratings for the item (i), and calculate the average of their rating as an estimate for (ru,i). Nevertheless, since some of these neighbors are more similar to the user (u) than others, we may need to use a weighted average instead. Ratings given by more similar users should be given more weight than the others. Here is a formula where a similarity score is used to weigh the ratings given by the user's neighbors:

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