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Mastering Machine Learning with scikit-learn

Mastering Machine Learning with scikit-learn

By : Gavin Hackeling
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Mastering Machine Learning with scikit-learn

Mastering Machine Learning with scikit-learn

5 (2)
By: Gavin Hackeling

Overview of this book

Machine learning is the buzzword bringing computer science and statistics together to build smart and efficient models. Using powerful algorithms and techniques offered by machine learning you can automate any analytical model. This book examines a variety of machine learning models including popular machine learning algorithms such as k-nearest neighbors, logistic regression, naive Bayes, k-means, decision trees, and artificial neural networks. It discusses data preprocessing, hyperparameter optimization, and ensemble methods. You will build systems that classify documents, recognize images, detect ads, and more. You will learn to use scikit-learn’s API to extract features from categorical variables, text and images; evaluate model performance, and develop an intuition for how to improve your model’s performance. By the end of this book, you will master all required concepts of scikit-learn to build efficient models at work to carry out advanced tasks with the practical approach.
Table of Contents (15 chapters)
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9
From Decision Trees to Random Forests and Other Ensemble Methods

Multi-class classification


In previous sections, we learned to use logistic regression for binary classification. In many classification problems, however, there are more than two classes that are of interest. We might wish to predict the genres of songs from samples of audio, or to classify images of galaxies by their types. The goal of multi-class classification is to assign an instance to one of set of classes. scikit-learn uses a strategy called one-versus-all, or one-versus-the-rest, to support multi-class classification. One-versus-all classification uses one binary classifier for each of the possible classes. The class that is predicted with the greatest confidence is assigned to the instance. LogisticRegression supports multi-class classification using the one-versus-all strategy out of the box. Let's use LogisticRegression for a multi-class classification problem.

Assume that you would like to watch a movie, but you have a strong aversion to watching bad movies. To inform your decision...

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