Book Image

Machine Learning Algorithms - Second Edition

Book Image

Machine Learning Algorithms - Second Edition

Overview of this book

Machine learning has gained tremendous popularity for its powerful and fast predictions with large datasets. However, the true forces behind its powerful output are the complex algorithms involving substantial statistical analysis that churn large datasets and generate substantial insight. This second edition of Machine Learning Algorithms walks you through prominent development outcomes that have taken place relating to machine learning algorithms, which constitute major contributions to the machine learning process and help you to strengthen and master statistical interpretation across the areas of supervised, semi-supervised, and reinforcement learning. Once the core concepts of an algorithm have been covered, you’ll explore real-world examples based on the most diffused libraries, such as scikit-learn, NLTK, TensorFlow, and Keras. You will discover new topics such as principal component analysis (PCA), independent component analysis (ICA), Bayesian regression, discriminant analysis, advanced clustering, and gaussian mixture. By the end of this book, you will have studied machine learning algorithms and be able to put them into production to make your machine learning applications more innovative.
Table of Contents (19 chapters)

ROC curve

The ROC curve is a valuable tool to compare different classifiers that can assign a score to their predictions. In general, this score can be interpreted as a probability, so it's bounded between 0 and 1. The plane is structured as shown in the following diagram:

Standard structure of an ROC plane

The x-axis represents the increasing false positive rate (1 - FPR) also known as 1 - Specificity, defined as follows:

The y-axis represents the true positive rate (TPR) also known as Sensitivity:

The dashed oblique line in the previous graph represents a perfectly random classifier (in a binary scenario, it's equivalent to tossing a fair coin to make every prediction), so all the curves below this threshold perform worse than a random choice, while the ones above it show better performance. Of course, the best classifier has an ROC curve split into the segments...