Book Image

Mastering Apache Spark 2.x - Second Edition

Book Image

Mastering Apache Spark 2.x - Second Edition

Overview of this book

Apache Spark is an in-memory, cluster-based Big Data processing system that provides a wide range of functionalities such as graph processing, machine learning, stream processing, and more. This book will take your knowledge of Apache Spark to the next level by teaching you how to expand Spark’s functionality and build your data flows and machine/deep learning programs on top of the platform. The book starts with a quick overview of the Apache Spark ecosystem, and introduces you to the new features and capabilities in Apache Spark 2.x. You will then work with the different modules in Apache Spark such as interactive querying with Spark SQL, using DataFrames and DataSets effectively, streaming analytics with Spark Streaming, and performing machine learning and deep learning on Spark using MLlib and external tools such as H20 and Deeplearning4j. The book also contains chapters on efficient graph processing, memory management and using Apache Spark on the cloud. By the end of this book, you will have all the necessary information to master Apache Spark, and use it efficiently for Big Data processing and analytics.
Table of Contents (21 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
10
Deep Learning on Apache Spark with DeepLearning4j and H2O

Using Datasets


This API as been introduced since Apache Spark 1.6 as experimental and finally became a first-class citizen in Apache Spark 2.0. It is basically a strongly typed version of DataFrames.

DataFrames are kept for backward compatibility and are not going to be deprecated for two reasons. First, a DataFrame since Apache Spark 2.0 is nothing else but a Dataset where the type is set to Row. This means that you actually lose the strongly static typing and fall back to a dynamic typing. This is also the second reason why DataFrames are going to stay. Dynamically typed languages such as Python or R are not capable of using Datasets because there isn't a concept of strong, static types in the language.

So what are Datasets exactly? Let's create one:

import spark.implicits._
case class Person(id: Long, name: String)
 val caseClassDS = Seq(Person(1,"Name1"),Person(2,"Name2")).toDS()

As you can see, we are defining a case class in order to determine the types of objects stored in the Dataset...