Create Vega-Lite specs & widgets with the vegalite package

By hrbrmstr

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Vega-Lite 1.0 was released this past week. I had been meaning to play with it for a while but I’ve been burned before by working with unstable APIs and was waiting for this to bake to a stable release. Thankfully, there were no new shows in the Fire TV, Apple TV or Netflix queues, enabling some fast-paced nocturnal coding to make an R htmlwidgets interface to the Vega-Lite code before the week was out.

What is “Vega” and why “-Lite”? Vega is “a full declarative visualization grammar, suitable for expressive custom interactive visualization design and programmatic generation.” Vega-Lite “provides a higher-level grammar for visual analysis, comparable to ggplot or Tableau, that generates complete Vega specifications.” Vega-Lite compiles to Vega and is more compact and accessible than Vega (IMO). Both are just JSON data files with a particular schema that let you encode the data, encodings and aesthetics for statistical charts.

Even I don’t like to write JSON by hand and I can’t imagine anyone really wanting to do that. I see Vega and Vega-Lite as amazing ways to serialize statistical charts from ggplot2 or even Tableau (or any Grammar of Graphics-friendly creation tool) and to pass around for use in other programs—like Voyager or Pole★—or directly on the web. It is “glued” to D3 (given the way data transformations are encoded and colors are specified) but it’s a pretty weak glue and one could make a Vega or Vega-Lite spec render to anything given some elbow grease.

But, enough words! Here’s how to make a simple Vega-Lite bar chart using vegalite:

# devtools::install_github("hrbrmstr/vegalite")

library(vegalite)
dat  jsonlite::fromJSON('[

    {"a": "A","b": 28}, {"a": "B","b": 55}, {"a": "C","b": 43},

    {"a": "D","b": 91}, {"a": "E","b": 81}, {"a": "F","b": 53},

    {"a": "G","b": 19}, {"a": "H","b": 87}, {"a":  ...read more
Source:: r-bloggers.com