Iain Dillingham

A Constellation of Data Visualization Tools

I gave a short talk today called A Constellation of Data Visualization Tools: Vega, Vega-Lite, and Altair.

The first part of the talk was a brief history of data visualization tools. I described how the ideas in Leland Wilkinson’s The Grammar of Graphics are related to those in ggplot2; and those in D3.js, Vega, Vega-Lite, and Altair.

The second part of the talk was a demonstration of Vega, Vega-Lite, and Altair. Using the editor and the examples, I showed that the JSON objects of a Vega specification are transformed into WebGL or SVG graphics by the runtime; that the JSON objects of a Vega-Lite specification are transformed into the JSON objects of a Vega specification by the runtime; and that the Python objects produced by Altair are serialized into the JSON objects of a Vega-Lite specification.

The third part of the talk related Vega, Vega-Lite, and Altair to the Bennett Institute and OpenSAFELY. Vega and Vega-Lite specifications are well suited to manual (human) and automated (machine) output checking. They can be themed, so a house style can be developed by a designer and applied by a researcher. Finally, they have expressive power and are effective: the former means they are capable of generating a large variety and quantity of ideas; the latter means they perform well, when compared to other notations, on the cognitive dimensions of notations framework.