Book Image

Hands-On Ensemble Learning with R

By : Prabhanjan Narayanachar Tattar
Book Image

Hands-On Ensemble Learning with R

By: Prabhanjan Narayanachar 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 (17 chapters)
Hands-On Ensemble Learning with R
Contributors
Preface
12
What's Next?
Index

Visualization and variable reduction


In the previous section, the housing data underwent a lot of analytical pre-processing, and we are now ready to further analyze this. First, we begin with visualization. Since we have a lot of variables, the visualization on the R visual device is slightly difficult. As seen in earlier chapters, to visualize the random forests and other large, complex structures, we will initiate a PDF device and store the graphs in it. In the housing dataset, the main variable is the housing price and so we will first name the output variable SalePrice. We need to visualize the data in a way that facilitates the relationship between the numerous variables and the SalePrice. The independent variables can be either numeric or categorical. If the variables are numeric, a scatterplot will indicate the kind of relationship between the variable and the SalePrice regressand. If the independent variable is categorical/factor, we will visualize the boxplot at each level of the...