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  • Book Overview & Buying Mastering Predictive Analytics with R
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Mastering Predictive Analytics with R

Mastering Predictive Analytics with R

3.9 (18)
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Mastering Predictive Analytics with R

Mastering Predictive Analytics with R

3.9 (18)

Overview of this book

This book is intended for the budding data scientist, predictive modeler, or quantitative analyst with only a basic exposure to R and statistics. It is also designed to be a reference for experienced professionals wanting to brush up on the details of a particular type of predictive model. Mastering Predictive Analytics with R assumes familiarity with only the fundamentals of R, such as the main data types, simple functions, and how to move data around. No prior experience with machine learning or predictive modeling is assumed, however you should have a basic understanding of statistics and calculus at a high school level.
Table of Contents (13 chapters)
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12
Index

Exploring the data

Before building and evaluating recommender systems using the two data sets 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:

Exploring the data

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...

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