Alexandre Bergel - Agile Visualization with Pharo: Crafting Interactive Visual Support Using Roassal

Alexandre Bergel

Agile Visualization with Pharo

Crafting Interactive Visual Support Using Roassal

1st ed.

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Any source code or other supplementary material referenced by the author in this book is available to readers on GitHub. For more detailed information, please visit http://www.apress.com/source-code.

About the Author

Alexandre Bergel

, Ph.D., is a professor (associate) at the Department of Computer Science (DCC), at the University of Chile and is a member of the Intelligent Software Construction laboratory (ISCLab). His research interests include software engineering, software performance, software visualization, programming environments, and machine learning. He is interested in improving the way we build and maintain software. His current hypotheses are validated using rigorous empirical methodologies. To make his research artifacts useful not only to stack papers, he co-founded Object Profile.

About the Technical Reviewer

Jason Whitehorn

is an experienced entrepreneur and software developer and has helped many companies automate and enhance their business solutions through data synchronization, SaaS architecture, and machine learning. Jason obtained his Bachelor of Science in Computer Science from Arkansas State University, but he traces his passion for development back many years before then, having first taught himself to program BASIC on his familys computer while in middle school. When hes not mentoring and helping his team at work, writing, or pursuing one of his many side-projects, Jason enjoys spending time with his wife and four children and living in the Tulsa, Oklahoma region. More information about Jason can be found on his website: https://jason.whitehorn.us .

Computers are a formidable extension of the human brain: a computer liberates us from performing boring and repetitive tasks. Data visualization is a wonderful field where computers nicely complement what the brain excels at.

Conveying information through interactive visualizations is both a sophisticated engineering process and an art. When crafting a visualization, many decisions have to be made based on a carefully evaluated design aspect or a personal intuition. Either way, being able to quickly experiment with a new idea is key. Agile Visualization is about leveraging creativity by reducing the cost associated with building visualizations.

Visualizing data is probably the easiest part of the field of data visualization. Numerous books and sophisticated libraries exist for that very purpose. One of challenges of data visualization is to identify the right abstractions to build a visualization that is reusable, composable, extensible, navigable, and produced at a very low cost. Roassal is a visualization engine for Pharo and Smalltalk that leverages the experience of crafting and using data visualization.

Roassal is written in the Pharo programming language. All the examples provided in this book are therefore made for Roassal and are written in the Pharo programming language.

Since there is no better way than programming to craft a visualization, readers are expected to have some programming experience to fully enjoy Agile visualization. This book is written for a large audience, and it provides the necessary technical background as a starter for programming with Pharo.

Agile visualization promotes the creation of a visualization based on very short, incremental steps. A data analysis is carried out by building a number of visualizations, many of which are simply attempts and have a very short usage time. Reducing the creation time of a visualization to a few seconds or minutes greatly increases the number of different paths the data scientist can take to solve a given problem.

Jackson Pollock, a famous American painter, once said: Splatter painting celebrates spontaneity, improvisation, and a highly physical approach to making art. Colors are thrown, mixed, and removed at will. This metaphor may be considered as a guiding line of Agile visualization. Similar to Agile programming, feedback should always occur a short time after the inception of a visualization.

Roassal is developed in the Pharo programming language . All the source code provided in this book is written in Pharo. Pharo is a dynamically typed programming language, sharing some flavors with Smalltalk, Python, and Ruby. Pharo is easy to install, learn, and use. Pharo has a very simple syntax, which means that the code is understandable as soon as you have some programming knowledge. Pharo is both a programming language and a powerful environment. This book provides a light introduction to the syntax of Pharo and presents an overview on how to use and extend its environment.

If you do not know Pharo, here are a few pieces of advice. Pharo is easy to learn and use. It comes with fantastic programming tools to make you intimately interact with