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Learning Spark SQL

You're reading from  Learning Spark SQL

Product type Book
Published in Sep 2017
Publisher Packt
ISBN-13 9781785888359
Pages 452 pages
Edition 1st Edition
Languages
Author (1):
Aurobindo Sarkar Aurobindo Sarkar
Profile icon Aurobindo Sarkar
Toc

Table of Contents (19) Chapters close

Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
1. Getting Started with Spark SQL 2. Using Spark SQL for Processing Structured and Semistructured Data 3. Using Spark SQL for Data Exploration 4. Using Spark SQL for Data Munging 5. Using Spark SQL in Streaming Applications 6. Using Spark SQL in Machine Learning Applications 7. Using Spark SQL in Graph Applications 8. Using Spark SQL with SparkR 9. Developing Applications with Spark SQL 10. Using Spark SQL in Deep Learning Applications 11. Tuning Spark SQL Components for Performance 12. Spark SQL in Large-Scale Application Architectures

Using SparkR for computing summary statistics


The describe (or summary) operation creates a new that contains count, mean, max, mean, and standard deviation values for a specified DataFrame or a list of numerical columns:

> sumstatsdf <- describe(df, "duration", "campaign", "previous", "age")

> showDF(sumstatsdf)

Computing these values on a large Dataset can be computationally expensive. Hence, we present the individual computation of these statistical measures here:

> avgagedf <- agg(df, mean = mean(df$age))

> showDF(avgagedf) # Print this DF
+-----------------+
| mean            |
+-----------------+
|40.02406040594348|
+-----------------+

Next, we create a DataFrame that lists the minimum and maximum values and the range width:

> agerangedf <- agg(df, minimum = min(df$age), maximum = max(df$age), range_width = abs(max(df$age) - min(df$age)))

> showDF(agerangedf)

 

Next, we compute the sample variance and standard deviation as shown here:

> agevardf <- agg...
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