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Spark for Data Science

You're reading from   Spark for Data Science Analyze your data and delve deep into the world of machine learning with the latest Spark version, 2.0

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Product type Paperback
Published in Sep 2016
Publisher Packt
ISBN-13 9781785885655
Length 344 pages
Edition 1st Edition
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Authors (2):
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Bikramaditya Singhal Bikramaditya Singhal
Author Profile Icon Bikramaditya Singhal
Bikramaditya Singhal
Srinivas Duvvuri Srinivas Duvvuri
Author Profile Icon Srinivas Duvvuri
Srinivas Duvvuri
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Toc

Table of Contents (12) Chapters Close

Preface 1. Big Data and Data Science – An Introduction FREE CHAPTER 2. The Spark Programming Model 3. Introduction to DataFrames 4. Unified Data Access 5. Data Analysis on Spark 6. Machine Learning 7. Extending Spark with SparkR 8. Analyzing Unstructured Data 9. Visualizing Big Data 10. Putting It All Together 11. Building Data Science Applications

Creating DataFrames


Spark DataFrame creation is similar to RDD creation. To get access to the DataFrame API, you need SQLContext or HiveContext as an entry point. In this section, we are going to demonstrate how to create DataFrames from various data sources, starting from basic code examples with in-memory collections:

Creating DataFrames from RDDs

The following code creates an RDD from a list of colors followed by a collection of tuples containing the color name and its length. It creates a DataFrame using the toDF method to convert the RDD into a DataFrame. The toDF method takes a list of column labels as an optional argument:

Python:

   //Create a list of colours 
>>> colors = ['white','green','yellow','red','brown','pink'] 
//Distribute a local collection to form an RDD 
//Apply map function on that RDD to get another RDD containing colour, length tuples 
>>> color_df = sc.parallelize(colors) 
        .map(lambda x:(x,len(x))).toDF(["color","length"]) 
 
>>&gt...
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