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Mastering Predictive Analytics with R, Second Edition

Mastering Predictive Analytics with R, Second Edition

By : James D. Miller , Rui Miguel Forte
5 (1)
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Mastering Predictive Analytics with R, Second Edition

Mastering Predictive Analytics with R, Second Edition

5 (1)
By: James D. Miller , Rui Miguel Forte

Overview of this book

R offers a free and open source environment that is perfect for both learning and deploying predictive modeling solutions. With its constantly growing community and plethora of packages, R offers the functionality to deal with a truly vast array of problems. The book begins with a dedicated chapter on the language of models and the predictive modeling process. You will understand the learning curve and the process of tidying data. Each subsequent chapter tackles a particular type of model, such as neural networks, and focuses on the three important questions of how the model works, how to use R to train it, and how to measure and assess its performance using real-world datasets. How do you train models that can handle really large datasets? This book will also show you just that. Finally, you will tackle the really important topic of deep learning by implementing applications on word embedding and recurrent neural networks. By the end of this book, you will have explored and tested the most popular modeling techniques in use on real- world datasets and mastered a diverse range of techniques in predictive analytics using R.
Table of Contents (16 chapters)
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8
8. Dimensionality Reduction
15
Index

Exploring the data


Before building and evaluating recommender systems using the two datasets we have loaded, it is a good idea to get a feel for the data. For one thing, we can make use of the getRatings() function to retrieve the ratings from a rating matrix. This is useful in order to construct a histogram of item ratings. Additionally, we can also normalize the ratings with respect to each user, as we discussed earlier. The following code snippet shows how we can compute ratings and normalized ratings for the jester data. We can then do the same for the MovieLens data and produce histograms for the ratings:

>jester_ratings<- getRatings(jester_rrm)
>jester_normalized_ratings<- getRatings(normalize(jester_rrm, 
                                          method = "Z-score"))

The following plot shows the different histograms:

In the Jester data, we can see that ratings above zero are more prominent than ratings below zero, and the most common rating is 10, the maximum rating. The...

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