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Machine Learning with Spark. - Second Edition

You're reading from  Machine Learning with Spark. - Second Edition

Product type Book
Published in Apr 2017
Publisher Packt
ISBN-13 9781785889936
Pages 532 pages
Edition 2nd Edition
Languages
Authors (2):
Rajdeep Dua Rajdeep Dua
Profile icon Rajdeep Dua
Manpreet Singh Ghotra Manpreet Singh Ghotra
Profile icon Manpreet Singh Ghotra
View More author details
Toc

Table of Contents (13) Chapters close

Preface 1. Getting Up and Running with Spark 2. Math for Machine Learning 3. Designing a Machine Learning System 4. Obtaining, Processing, and Preparing Data with Spark 5. Building a Recommendation Engine with Spark 6. Building a Classification Model with Spark 7. Building a Regression Model with Spark 8. Building a Clustering Model with Spark 9. Dimensionality Reduction with Spark 10. Advanced Text Processing with Spark 11. Real-Time Machine Learning with Spark Streaming 12. Pipeline APIs for Spark ML

Evaluating dimensionality reduction models

Both PCA and SVD are deterministic models. That is, given a certain input dataset, they will always produce the same result. This is in contrast to many of the models we have seen so far, which depend on some random element (most often for the initialization of model weight vectors, and so on).

Both models are also guaranteed to return the top principal components or singular values, and hence, the only parameter is k. Like clustering models, increasing k always improves the model performance (for clustering, the relevant error function, while for PCA and SVD, the total amount of variability explained by the k components). Therefore, selecting a value for k is a trade-off between capturing as much structure of the data as possible while keeping the dimensionality of projected data low.

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