Book Image

Scala for Data Science

By : Pascal Bugnion
Book Image

Scala for Data Science

By: Pascal Bugnion

Overview of this book

Scala is a multi-paradigm programming language (it supports both object-oriented and functional programming) and scripting language used to build applications for the JVM. Languages such as R, Python, Java, and so on are mostly used for data science. It is particularly good at analyzing large sets of data without any significant impact on performance and thus Scala is being adopted by many developers and data scientists. Data scientists might be aware that building applications that are truly scalable is hard. Scala, with its powerful functional libraries for interacting with databases and building scalable frameworks will give you the tools to construct robust data pipelines. This book will introduce you to the libraries for ingesting, storing, manipulating, processing, and visualizing data in Scala. Packed with real-world examples and interesting data sets, this book will teach you to ingest data from flat files and web APIs and store it in a SQL or NoSQL database. It will show you how to design scalable architectures to process and modelling your data, starting from simple concurrency constructs such as parallel collections and futures, through to actor systems and Apache Spark. As well as Scala’s emphasis on functional structures and immutability, you will learn how to use the right parallel construct for the job at hand, minimizing development time without compromising scalability. Finally, you will learn how to build beautiful interactive visualizations using web frameworks. This book gives tutorials on some of the most common Scala libraries for data science, allowing you to quickly get up to speed with building data science and data engineering solutions.
Table of Contents (22 chapters)
Scala for Data Science
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Querying external APIs and consuming JSON


So far, we have learnt how to provide the user with a dummy JSON array of repositories in response to a request to /api/repos/:username. In this section, we will replace the dummy data with the user's actual repositories, dowloaded from GitHub.

In Chapter 7, Web APIs, we learned how to query the GitHub API using Scala's Source.fromURL method and scalaj-http. It should come as no surprise that the Play framework implements its own library for interacting with external web services.

Let's edit the Api controller to fetch information about a user's repositories from GitHub, rather than using dummy data. When called with a username as argument, the controller will:

  1. Send a GET request to the GitHub API for that user's repositories.

  2. Interpret the response, converting the body from a JSON object to a List[Repo].

  3. Convert from the List[Repo] to a JSON array, forming the response.

We start by giving the full code listing before explaining the thornier parts in detail...