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Machine Learning with R Cookbook, Second Edition

You're reading from   Machine Learning with R Cookbook, Second Edition Analyze data and build predictive models

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Product type Paperback
Published in Oct 2017
Publisher Packt
ISBN-13 9781787284395
Length 572 pages
Edition 2nd Edition
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Authors (2):
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Ashish Bhatia Ashish Bhatia
Author Profile Icon Ashish Bhatia
Ashish Bhatia
Yu-Wei, Chiu (David Chiu) Yu-Wei, Chiu (David Chiu)
Author Profile Icon Yu-Wei, Chiu (David Chiu)
Yu-Wei, Chiu (David Chiu)
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Table of Contents (15) Chapters Close

Preface 1. Practical Machine Learning with R FREE CHAPTER 2. Data Exploration with Air Quality Datasets 3. Analyzing Time Series Data 4. R and Statistics 5. Understanding Regression Analysis 6. Survival Analysis 7. Classification 1 - Tree, Lazy, and Probabilistic 8. Classification 2 - Neural Network and SVM 9. Model Evaluation 10. Ensemble Learning 11. Clustering 12. Association Analysis and Sequence Mining 13. Dimension Reduction 14. Big Data Analysis (R and Hadoop)

Tuning a support vector machine


Besides using different feature sets and the kernel function in support vector machines, one trick that you can use to tune its performance is to adjust the gamma and cost configured in the argument. One possible approach to test the performance of different gamma and cost combination values is to write a for loop to generate all the combinations of gamma and cost as inputs to train different support vector machines. Fortunately, SVM provides a tuning function, tune.svm, which makes the tuning much easier. In this recipe, we will demonstrate how to tune a support vector machine through the use of tune.svm.

Getting ready

Before completing this recipe, you need to have completed the previous recipe by preparing a training dataset, trainset.

How to do it...

Perform the following steps to tune the support vector machine:

  1. First, tune the support vector machine using tune.svm:
        > tuned = tune.svm(churn~., data = trainset, gamma = 10^(-6:-1),
        cost = 10...
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