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Mastering Machine Learning with R

You're reading from   Mastering Machine Learning with R Master machine learning techniques with R to deliver insights for complex projects

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Product type Paperback
Published in Oct 2015
Publisher
ISBN-13 9781783984527
Length 400 pages
Edition 1st Edition
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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 (15) Chapters Close

Preface 1. A Process for Success 2. Linear Regression – The Blocking and Tackling of Machine Learning FREE CHAPTER 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 8. Cluster Analysis 9. Principal Components Analysis 10. Market Basket Analysis and Recommendation Engines 11. Time Series and Causality 12. Text Mining A. R Fundamentals Index

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 in 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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