Book Image

Hands-On Unsupervised Learning with Python

By : Giuseppe Bonaccorso
Book Image

Hands-On Unsupervised Learning with Python

By: Giuseppe Bonaccorso

Overview of this book

Unsupervised learning is about making use of raw, untagged data and applying learning algorithms to it to help a machine predict its outcome. With this book, you will explore the concept of unsupervised learning to cluster large sets of data and analyze them repeatedly until the desired outcome is found using Python. This book starts with the key differences between supervised, unsupervised, and semi-supervised learning. You will be introduced to the best-used libraries and frameworks from the Python ecosystem and address unsupervised learning in both the machine learning and deep learning domains. You will explore various algorithms, techniques that are used to implement unsupervised learning in real-world use cases. You will learn a variety of unsupervised learning approaches, including randomized optimization, clustering, feature selection and transformation, and information theory. You will get hands-on experience with how neural networks can be employed in unsupervised scenarios. You will also explore the steps involved in building and training a GAN in order to process images. By the end of this book, you will have learned the art of unsupervised learning for different real-world challenges.
Table of Contents (12 chapters)

Autoencoders

In Chapter 7, Dimensionality Reduction And Component Analysis, we discussed some common methods that can be employed to reduce the dimensionality of a dataset, given its peculiar statistical properties (for example, the covariance matrix). However, when complexity increases, even kernel principal component analysis (kernel PCA) might be unable to find a suitable lower-dimensional representation. In other words, the loss of information can overcome a threshold that guarantees the possibility of rebuilding the samples effectively. Autoencoders are models that exploit the extreme non-linearity of neural networks, in order to find low-dimensional representations of a given dataset. In particular, let's assume that X is a set of samples drawn from a data-generating process, pdata(x). For simplicity, we will consider xi ∈ ℜn, but there are no restrictions...