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

Image classification

Now that we have our data ready, we can predict the digits using the nearest neighbors classifier, as follows:

from sklearn.neighbors import KNeighborsClassifier

clf = KNeighborsClassifier(n_neighbors=11, metric='manhattan')
clf.fit(x_train, y_train)
y_test_pred = clf.predict(x_test)

For this example, I set n_neighbors to 11 and metric to manhattan, meaning at prediction time, we compare each new sample to the 11 nearest training samples, using the Manhattan distance to evaluate how near they are. More on these parameters in a bit. This model made predictions with an accuracy of 96.4% on the test set. This might sound reasonable, but I'm sorry to break it to you; this isn't a fantastic score for this particular dataset. Anyway, let's keep on dissecting the model's performance further.

Using a confusion matrix to understand the model's mistakes

When dealing with a dataset with 10 class labels...