Book Image

Python: Advanced Guide to Artificial Intelligence

By : Giuseppe Bonaccorso, Rajalingappaa Shanmugamani
Book Image

Python: Advanced Guide to Artificial Intelligence

By: Giuseppe Bonaccorso, Rajalingappaa Shanmugamani

Overview of this book

This Learning Path is your complete guide to quickly getting to grips with popular machine learning algorithms. You'll be introduced to the most widely used algorithms in supervised, unsupervised, and semi-supervised machine learning, and learn how to use them in the best possible manner. Ranging from Bayesian models to the MCMC algorithm to Hidden Markov models, this Learning Path will teach you how to extract features from your dataset and perform dimensionality reduction by making use of Python-based libraries. You'll bring the use of TensorFlow and Keras to build deep learning models, using concepts such as transfer learning, generative adversarial networks, and deep reinforcement learning. Next, you'll learn the advanced features of TensorFlow1.x, such as distributed TensorFlow with TF clusters, deploy production models with TensorFlow Serving. You'll implement different techniques related to object classification, object detection, image segmentation, and more. By the end of this Learning Path, you'll have obtained in-depth knowledge of TensorFlow, making you the go-to person for solving artificial intelligence problems This Learning Path includes content from the following Packt products: • Mastering Machine Learning Algorithms by Giuseppe Bonaccorso • Mastering TensorFlow 1.x by Armando Fandango • Deep Learning for Computer Vision by Rajalingappaa Shanmugamani
Table of Contents (31 chapters)
Title Page
About Packt
Tensor Processing Units

Gaussian mixture

In Chapter 2, Introduction to Semi-Supervised Learning, we discussed the generative Gaussian mixture model in the context of semi-supervised learning. In this paragraph, we're going to apply the EM algorithm to derive the formulas for the parameter updates.

Let's start considering a dataset, X, drawn from a data generating process, pdata:

We assume that the whole distribution is generated by the sum of k Gaussian distributions so that the probability of each sample can be expressed as follows:

In the previous expression, the term wj = P(N=j) is the relative weight of the jth Gaussian, while μj and Σj are the mean and the covariance matrix. For consistency with the laws of probability, we also need to impose the following:

Unfortunately, if we try to solve the problem directly, we need to manage the logarithm of a sum and the procedure becomes very complex. However, we have learned that it's possible to use latent variables as helpers, whenever this trick can simplify the solution...