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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

k-NN bagging

The k-NN classifier introduced a classification model in the previous section. We can make this robust using the bootstrap method. The broader algorithm remains the same. As with the typical bootstrap method, we can always write a program consisting of the loop and depending on the number of required bootstrap samples, or bags, the control can be specified easily. However, here we will use a function from the FNN R package. The ownn function is useful for carrying out the bagging method on the k-NN classifier.

The ownn function requires all variables in the dataset to be numeric. However, we do have many variables that are factor variables. Consequently, we need to tweak the data so that we can use the ownn function. The covariate data from the training and test dataset are first put together using the rbind function. Using the model.matrix function with the formula ~.-1, we convert all factor variables into numeric variables. The important question here is how does the model...

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