In the previous section, we have seen that sampling with a replacement leads to datasets where the samples are randomly reweighted. However, if M is very large, most of the samples will appear only once and, moreover, all the choices are totally random. AdaBoost is an algorithm proposed by Schapire and Freund that tries to maximize the efficiency of each weak learner by employing adaptive boosting (the name derives from this). In particular, the ensemble is grown sequentially and the data distribution is recomputed at each step so as to increase the weight of those samples that were misclassified and reduce the weight of the ones that were correctly classified. In this way, every new learner is forced to focus on those regions that were more problematic for the previous estimators. The reader can immediately understand that, contrary to random forests and other bagging methods, boosting doesn't rely on randomness to reduce the variance and improve the accuracy. Rather, it works...
Mastering Machine Learning Algorithms
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.
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Current Title:
Mastering Machine Learning Algorithms
Table of Contents (22 chapters)
Title Page
Dedication
Packt Upsell
Contributors
Preface
Free Chapter
Machine Learning Model Fundamentals
Introduction to Semi-Supervised Learning
Graph-Based Semi-Supervised Learning
Bayesian Networks and Hidden Markov Models
EM Algorithm and Applications
Hebbian Learning and Self-Organizing Maps
Clustering Algorithms
Ensemble Learning
Neural Networks for Machine Learning
Advanced Neural Models
Autoencoders
Generative Adversarial Networks
Deep Belief Networks
Introduction to Reinforcement Learning
Advanced Policy Estimation Algorithms
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Index
Customer Reviews