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Mastering Machine Learning with R, Second Edition

You're reading from   Mastering Machine Learning with R, Second Edition Advanced prediction, algorithms, and learning methods with R 3.x

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Product type Paperback
Published in Apr 2017
Publisher Packt
ISBN-13 9781787287471
Length 420 pages
Edition 2nd 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 (17) Chapters Close

Preface 1. A Process for Success FREE CHAPTER 2. Linear Regression - The Blocking and Tackling of Machine Learning 3. Logistic Regression and Discriminant Analysis 4. Advanced Feature Selection in Linear Models 5. More Classification Techniques - K-Nearest Neighbors and Support Vector Machines 6. Classification and Regression Trees 7. Neural Networks and Deep Learning 8. Cluster Analysis 9. Principal Components Analysis 10. Market Basket Analysis, Recommendation Engines, and Sequential Analysis 11. Creating Ensembles and Multiclass Classification 12. Time Series and Causality 13. Text Mining 14. R on the Cloud 15. R Fundamentals 16. Sources

Feature selection for SVMs


However, all is not lost on feature selection and I want to take some space to show you a quick way of how to begin exploring this matter. It will require some trial and error on your part. Again, the caret package helps out in this matter as it will run a cross-validation on a linear SVM based on the kernlab package.

To do this, we will need to set the random seed, specify the cross-validation method in the caret's rfeControl() function, perform a recursive feature selection with the rfe() function, and then test how the model performs on the test set. In rfeControl(), you will need to specify the function based on the model being used. There are several different functions that you can use. Here we will need lrFuncs. To see a list of the available functions, your best bet is to explore the documentation with ?rfeControl and ?caretFuncs. The code for this example is as follows:

> set.seed(123)
> rfeCNTL <- rfeControl(functions = lrFuncs, method = "cv",...
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