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Mastering Machine Learning with R

You're reading from   Mastering Machine Learning with R Advanced machine learning techniques for building smart applications with R 3.5

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Product type Paperback
Published in Jan 2019
Publisher
ISBN-13 9781789618006
Length 354 pages
Edition 3rd Edition
Languages
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Author (1):
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Cory Lesmeister Cory Lesmeister
Author Profile Icon Cory Lesmeister
Cory Lesmeister
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Table of Contents (16) Chapters Close

Preface 1. Preparing and Understanding Data 2. Linear Regression FREE CHAPTER 3. Logistic Regression 4. Advanced Feature Selection in Linear Models 5. K-Nearest Neighbors and Support Vector Machines 6. Tree-Based Classification 7. Neural Networks and Deep Learning 8. Creating Ensembles and Multiclass Methods 9. Cluster Analysis 10. Principal Component Analysis 11. Association Analysis 12. Time Series and Causality 13. Text Mining 14. Creating a Package 15. Other Books You May Enjoy

Classifying text

Our goal here is to build a classifier to predict Presidential party affiliation, either Democrat or Republican, since 1900. We will turn the word counts per year into features, create a DTM, create features using the term frequency-inverse document frequency (tf-idf), and use them in our model. As you can imagine, we will have thousands of features, so we will change how the data is prepared versus what we covered in prior sections, and also use the text2vec package for feature creation and modeling.

Data preparation

We'll start by getting the pertinent data period. Then, we'll take a look at a table of the labels:

> sotu_party <- sotu_meta %>%
dplyr::filter(year > 1899)

> table...
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