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Machine Learning with R Cookbook, Second Edition - Second Edition

You're reading from  Machine Learning with R Cookbook, Second Edition - Second Edition

Product type Book
Published in Oct 2017
Publisher Packt
ISBN-13 9781787284395
Pages 572 pages
Edition 2nd Edition
Languages
Author (1):
Yu-Wei, Chiu (David Chiu) Yu-Wei, Chiu (David Chiu)
Profile icon Yu-Wei, Chiu (David Chiu)
Toc

Table of Contents (21) Chapters close

Title Page
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface
1. Practical Machine Learning with R 2. Data Exploration with Air Quality Datasets 3. Analyzing Time Series Data 4. R and Statistics 5. Understanding Regression Analysis 6. Survival Analysis 7. Classification 1 - Tree, Lazy, and Probabilistic 8. Classification 2 - Neural Network and SVM 9. Model Evaluation 10. Ensemble Learning 11. Clustering 12. Association Analysis and Sequence Mining 13. Dimension Reduction 14. Big Data Analysis (R and Hadoop)

Reducing dimensions with SVD


Singular Value Decomposition (SVD) is a type of matrix factorization (decomposition), which can factorize matrices into two orthogonal matrices and diagonal matrices. You can multiply the original matrix back using these three matrices. SVD can reduce redundant data that is linear dependent from the perspective of linear algebra. Therefore, it can be applied to feature selection, image processing, clustering, and many other fields. In this recipe, we will illustrate how to perform dimension reduction with SVD.

Getting ready

In this recipe, we will continue using the dataset, swiss, as our input data source.

How to do it...

Perform the following steps to perform dimension reduction using SVD:

  1. First, you can perform svd on the swiss dataset:
        > swiss.svd = svd(swiss)  
  1. You can then plot the percentage of variance explained and the cumulative variance explained in accordance with the SVD column:
        > plot(swiss.svd$d^2/sum(swiss.svd$d^2), type="l", xlab...
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