About the Vega Project

Over years working in data visualization, we’ve sought to build tools that help designers craft sophisticated graphics, including systems such as Prefuse, Protovis and D3.js. However, in the grand scheme of things, “artisanal” visualizations hand-coded by skilled designers are the exception, not the rule. The vast majority of the world’s visualizations instead are produced using end-user applications such as spreadsheets and business intelligence tools. While valuable, these tools often fall short of fully supporting the iterative, interactive process of data analysis. Improved tools could help a larger swath of people create effective visualizations and better understand their data.

The goal of the Vega project is to promote an ecosystem of usable and interoperable tools, supporting use cases ranging from exploratory data analysis to effective communication via custom visualization design.

This goal has led us to develop not a singular system, but rather a stack of tools for interactive data visualization. At the foundation of this stack is the Vega visualization grammar. Similar in spirit to how SQL provides a language for expressing database queries, Vega provides a declarative language for describing visualizations. Vega specifications include the data transformations and visual encoding rules needed to express a rich space of visualizations. Building on libraries such as D3, the Vega runtime parses specifications in a JSON format to produce interactive web-based graphics. One unique aspect of Vega is its support for declarative interaction design: instead of the “spaghetti code” of event handler callbacks, Vega treats user input (mouse movement, touch events, etc.) as first-class streaming data to drive reactive updates to a visualization.

While Vega is useful in its own right (for example, Vega is deployed on Wikipedia to define visualizations directly within wiki pages), our primary motivation is for Vega to serve as a foundation for higher-level tools. Vega provides a formal language and computational file format for representing and reasoning about visualizations. In other words, Vega provides a more convenient yet powerful means for writing programs that generate visualizations, ranging from interactive design tools to automatic chart recommendation tools. Vega provides a performant runtime and can serve as an “assembly language” for visualization, letting other tools focus on design questions rather than low-level implementation details.

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