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Hands-On Ensemble Learning with R

Hands-On Ensemble Learning with R

By : Tattar
3 (1)
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Hands-On Ensemble Learning with R

Hands-On Ensemble Learning with R

3 (1)
By: Tattar

Overview of this book

Ensemble techniques are used for combining two or more similar or dissimilar machine learning algorithms to create a stronger model. Such a model delivers superior prediction power and can give your datasets a boost in accuracy. Hands-On Ensemble Learning with R begins with the important statistical resampling methods. You will then walk through the central trilogy of ensemble techniques – bagging, random forest, and boosting – then you'll learn how they can be used to provide greater accuracy on large datasets using popular R packages. You will learn how to combine model predictions using different machine learning algorithms to build ensemble models. In addition to this, you will explore how to improve the performance of your ensemble models. By the end of this book, you will have learned how machine learning algorithms can be combined to reduce common problems and build simple efficient ensemble models with the help of real-world examples.
Table of Contents (15 chapters)
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12
12. What's Next?
13
A. Bibliography
14
Index

Ensembling by voting

Ensembling by voting can be used efficiently for classification problems. We now have a set of classifiers, and we need to use them to predict the class of an unknown case. The combining of the predictions of the classifiers can proceed in multiple ways. The two options that we will consider are majority voting, and weighted voting.

Majority voting

Ideas related to voting will be illustrated through an ensemble based on the homogeneous base learners of decision trees, as used in the development of bagging and random forests. First, we will create 500 base learners using the randomForest function and repeat the program in the first block, as seen in Chapter 4, Random Forests. Ensembling has already been performed in that chapter, and we will elaborate on those steps here. First, the code block for setting up the random forest is given here:

> load("../Data/GC2.RData")
> set.seed(12345)
> Train_Test <- sample(c("Train","Test"),nrow...

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