Book Image

Learning PySpark

By : Tomasz Drabas, Denny Lee
Book Image

Learning PySpark

By: Tomasz Drabas, Denny 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 (20 chapters)
Learning PySpark
Credits
Foreword
About the Authors
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
Index

Understanding motifs


To easily understand the complex relationship of city airports and the flights between each other, we can use motifs to find patterns of airports (for example, vertices) connected by flights (that is, edges). The result is a DataFrame in which the column names are given by the motif keys. Note that motif finding is one of the new graph algorithms supported as part of GraphFrames.

For example, let's determine the delays that are due to San Francisco International Airport (SFO):

# Generate motifs
motifs = tripGraphPrime.find("(a)-[ab]->(b); (b)-[bc]->(c)")\
  .filter("(b.id = 'SFO') and (ab.delay > 500 or bc.delay > 500) and bc.tripid > ab.tripid and bc.tripid < ab.tripid + 10000")

# Display motifs
display(motifs)

Breaking down the preceding query, the (x) represents the vertex (that is, airport) while the [xy] represents the edge (that is, flights between airports). Therefore, to determine the delays that are due to SFO, use the following:

  • The vertex (b...