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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

MLR's ensemble

Here is something we haven't found too easy: the Pima diabetes classification. Like caret, you can build ensemble models, so let's give that a try. I will also show how to incorporate SMOTE into the learning process instead of creating a separate dataset.

First, make sure you run the code from the beginning of this chapter to create the train and test sets. I'll pause here and let you take care of that.

Great, now let's create the training task as before:

    > pima.task <- makeClassifTask(id = "pima", data = train, target = 
"type")

The smote() function here is a little different from what we did before. You just have to specify the rate of minority oversample and the k-nearest neighbors. We will double our minority class (Yes) based on the three nearest neighbors:

    > pima.smote <- smote(pima.task, rate = 2, nn = 3)

> str...
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