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)

K-means

In the previous section, we discussed an algorithm based on the assumption that the data-generating process can be represented as a weighted sum of multivariate Gaussian distributions. What happens when the covariance matrices are shrunk towards zero? As it's easy to imagine, when Σi → 0, the corresponding distribution degenerates to a Dirac's Delta centered on the mean. In other words, the probability will become almost 1 if the sample is extremely close to the mean, and 0 otherwise. In this case, the membership to a cluster becomes binary and it's determined only by the distance between the sample and the mean (the shortest distance will determine the winning cluster).

The K-means algorithm is the natural hard extension of Gaussian mixture and it's characterized by k (pre-determined) centroids or means (which justifies the name):

The...