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)

Spectral Clustering

Spectral Clustering is a more sophisticated approach based on the G={V, E} graph of the dataset. The set of vertices, V, is made up of the samples, while the edges, E, connecting two different samples are weighted according to an affinity measure, whose value is proportional to the distance of two samples in the original space or in a more suitable one (in a way analogous to Kernel SVMs).

If there are n samples, it's helpful to introduce a symmetric affinity matrix:

Each element wij represents a measure of affinity between two samples. The most diffuse measures (also supported by scikit-learn) are the Radial Basis Function (RBF) and k-Nearest Neighbors (k-NN). The former is defined as follows:

The latter is based on a parameter, k, defining the number of neighbors:

RBF is always non-null, while k-NN can yield singular affinity matrices if the graph...