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Learning PySpark

Learning PySpark

By : Drabas, Lee
3.9 (194)
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Learning PySpark

Learning PySpark

3.9 (194)
By: Drabas, Lee

Overview of this book

Apache Spark is an open source framework for efficient cluster computing with a strong interface for data parallelism and fault tolerance. This book will show you how to leverage the power of Python and put it to use in the Spark ecosystem. You will start by getting a firm understanding of the Spark 2.0 architecture and how to set up a Python environment for Spark. You will get familiar with the modules available in PySpark. You will learn how to abstract data with RDDs and DataFrames and understand the streaming capabilities of PySpark. Also, you will get a thorough overview of machine learning capabilities of PySpark using ML and MLlib, graph processing using GraphFrames, and polyglot persistence using Blaze. Finally, you will learn how to deploy your applications to the cloud using the spark-submit command. By the end of this book, you will have established a firm understanding of the Spark Python API and how it can be used to build data-intensive applications.
Table of Contents (13 chapters)
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12
Index

Interoperating with RDDs


There are two different methods for converting existing RDDs to DataFrames (or Datasets[T]): inferring the schema using reflection, or programmatically specifying the schema. The former allows you to write more concise code (when your Spark application already knows the schema), while the latter allows you to construct DataFrames when the columns and their data types are only revealed at run time. Note, reflection is in reference to schema reflection as opposed to Python reflection.

Inferring the schema using reflection

In the process of building the DataFrame and running the queries, we skipped over the fact that the schema for this DataFrame was automatically defined. Initially, row objects are constructed by passing a list of key/value pairs as **kwargs to the row class. Then, Spark SQL converts this RDD of row objects into a DataFrame, where the keys are the columns and the data types are inferred by sampling the data.

Tip

The **kwargs construct allows you to pass...

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