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Hands-On Machine Learning with scikit-learn and Scientific Python Toolkits

You're reading from   Hands-On Machine Learning with scikit-learn and Scientific Python Toolkits A practical guide to implementing supervised and unsupervised machine learning algorithms in Python

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Product type Paperback
Published in Jul 2020
Publisher Packt
ISBN-13 9781838826048
Length 384 pages
Edition 1st Edition
Languages
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Author (1):
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Tarek Amr Tarek Amr
Author Profile Icon Tarek Amr
Tarek Amr
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Table of Contents (18) Chapters Close

Preface 1. Section 1: Supervised Learning
2. Introduction to Machine Learning FREE CHAPTER 3. Making Decisions with Trees 4. Making Decisions with Linear Equations 5. Preparing Your Data 6. Image Processing with Nearest Neighbors 7. Classifying Text Using Naive Bayes 8. Section 2: Advanced Supervised Learning
9. Neural Networks – Here Comes Deep Learning 10. Ensembles – When One Model Is Not Enough 11. The Y is as Important as the X 12. Imbalanced Learning – Not Even 1% Win the Lottery 13. Section 3: Unsupervised Learning and More
14. Clustering – Making Sense of Unlabeled Data 15. Anomaly Detection – Finding Outliers in Data 16. Recommender System – Getting to Know Their Taste 17. Other Books You May Enjoy

Vectorizing text into matrices

In text mining, a dataset is usually called a corpus. Each data sample in it is usually called a document. Documents are made of tokens, and a set of distinct tokens is called a vocabulary. Putting this information into a matrix is called vectorization. In the following sections, we are going to see the different kinds of vectorizations that we can get.

Vector space model

We still miss our beloved feature matrices, where we expect each token to have its own column and each document to be represented by a separate row. This kind of representation for textual data is known as the vectorspace model. From a linear-algebraic point of view, the documents in this representation are seen as vectors (rows), and the different terms are the dimensions of this space (columns), hence the name vector space model. In the next section, we will learn how to vectorize our documents.

Bag of words

We need to convert the documents into...

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