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)

Passive-aggressive algorithms

In this section, we are going to analyze an algorithm that can be efficiently employed for online linear classifications. In fact, one of the problems with other methods is that when new samples are collected, the whole model must be retrained. The main idea proposed by Crammer et al. (in Online Passive-Aggressive Algorithms, Crammer K., Dekel O., Keshet J., Shalev-Shwartz S., Singer Y., Journal of Machine Learning Research 7 (2006) 551–585) is to train a model incrementally, allowing modifications of the parameters only when needed, while discarding all the updates that don't alter the equilibrium. In the original paper, three variants were proposed. In this description, we are considering the one called PA-II (which is the most flexible).

For simplicity, in this description we are assuming bipolar outputs (-1, +1); however, there are...