Book Image

Mastering Machine Learning Algorithms

Book Image

Mastering Machine Learning Algorithms

Overview of this book

Machine learning is a subset of AI that aims to make modern-day computer systems smarter and more intelligent. The real power of machine learning resides in its algorithms, which make even the most difficult things capable of being handled by machines. However, with the advancement in the technology and requirements of data, machines will have to be smarter than they are today to meet the overwhelming data needs; mastering these algorithms and using them optimally is the need of the hour. Mastering Machine Learning Algorithms is your complete guide to quickly getting to grips with popular machine learning algorithms. You will be introduced to the most widely used algorithms in supervised, unsupervised, and semi-supervised machine learning, and will learn how to use them in the best possible manner. Ranging from Bayesian models to the MCMC algorithm to Hidden Markov models, this book will teach you how to extract features from your dataset and perform dimensionality reduction by making use of Python-based libraries such as scikit-learn v0.19.1. You will also learn how to use Keras and TensorFlow 1.x to train effective neural networks. If you are looking for a single resource to study, implement, and solve end-to-end machine learning problems and use-cases, this is the book you need.
Table of Contents (22 chapters)
Title Page
Dedication
Packt Upsell
Contributors
Preface
13
Deep Belief Networks
Index

K-means


When we discussed the Gaussian mixture algorithm, we defined it as Soft K-means. The reason is that each cluster was represented by three elements: mean, variance, and weight. Each sample always belongs to all clusters with a probability provided by the Gaussian distributions. This approach can be very useful when it's possible to manage the probabilities as weights, but in many other situations, it's preferable to determine a single cluster per sample. Such an approach is called hard clustering and K-means can be considered the hard version of a Gaussian mixture. In fact, when all variances Σi → 0, the distributions degenerate to Dirac's Deltas, which represent perfect spikes centered at a specific point. In this scenario, the only possibility to determine the most appropriate cluster is to find the shortest distance between a sample point and all the centers (from now on, we are going to call them centroids). This approach is also based on an important double principle that should...