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Hands-On Ensemble Learning with R

You're reading from  Hands-On Ensemble Learning with R

Product type Book
Published in Jul 2018
Publisher Packt
ISBN-13 9781788624145
Pages 376 pages
Edition 1st Edition
Languages
Author (1):
Prabhanjan Narayanachar Tattar Prabhanjan Narayanachar Tattar
Profile icon Prabhanjan Narayanachar Tattar
Toc

Table of Contents (17) Chapters close

Hands-On Ensemble Learning with R
Contributors
Preface
1. Introduction to Ensemble Techniques 2. Bootstrapping 3. Bagging 4. Random Forests 5. The Bare Bones Boosting Algorithms 6. Boosting Refinements 7. The General Ensemble Technique 8. Ensemble Diagnostics 9. Ensembling Regression Models 10. Ensembling Survival Models 11. Ensembling Time Series Models 12. What's Next?
Bibliography Index

Comparisons with bagging


When comparing the random forest results with the bagging counterpart for the German credit data and Pima Indian Diabetes datasets, we did not see much improvement in the accuracy over the validated partition of the data. A potential reason might be that the variability reduction achieved by bagging is at the optimum reduced variance, and that any bias improvement will not lead to an increase in the accuracy.

We consider a dataset to be available from the R core package kernlab. The dataset is spam and it has a collection of 4601 emails with labels that state whether the email is spam or non-spam. The dataset has a good collection of 57 variables derived from the email contents. The task is to build a good classifier for the spam identification problem. The dataset is quickly partitioned into training and validation partitions, as with earlier problems:

> data("spam")
> set.seed(12345)
> Train_Test <- sample(c("Train","Test"),nrow(spam),replace = TRUE,...
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