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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

Proximity plots

According to Hastie, et al. (2009), "one of the advertised outputs of a random forest is a proximity plot" (see page 595). But what are proximity plots? If we have n observations in the training dataset, a proximity matrix of order Proximity plots is created. Here, the matrix is initialized with all the values at 0. Whenever a pair of observations such as OOB occur jointly in the terminal node of a tree, the proximity count is increased by 1. The proximity matrix is visualized using the multidimensional scaling method, a concept beyond the scope of this chapter, where the proximity matrix is represented in two dimensions. The proximity plots give an indication of which points are closer to each other from the perspective of the random forest.

In the earlier creation of random forests, we had not specified the option of a proximity matrix. Thus, we will first create the random forest using the option of proximity as follows:

> GC2_RF3 <- randomForest(GC2_Formula,data=GC2_Train...

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