vegabrite: Iteratively build vega-lite specs in R

The goal of vegabrite is to provide an R api for building up vega-lite specs. For a guide on getting started using vegabrite, check out the getting started vignette. The example gallery show-cases some of the many different types of plots that can be made using vegabrite.

Current status

This package is still experimental but has a mostly complete interface for building out Vega-Lite specs and charts. There is still lots of room for improvement in terms of better error handling and warnings when making invalid specs.

Design & Building

For some background and context on the package (previously named vegabrite) you can check out slides from a rstudio::conf talk in January 2020. See also the design vignette for an overview of the design of the package.

Much of the public API is auto-generated via the build.R script in the build directory. The script makes uses of another package, vlmetabuildr located within the build directory.

Inspiration and related work

The API for this package is heavily inspired by the vegalite R package, but is rebuilt from scratch to (1) build up the API semi-automatically based on the Vega-lite schema (an approach inspired by Altair and vega-lite-api) and (2) take advantage of the htmlwidget infrastucture for vega specs provided by the vegawidget package.

Installation

vegabrite is not yet on cran but can be installed from github:

remotes::install_github('vegawidget/vegabrite')

Examples

These are some examples showing current capabilities; see examples vignette for more examples, including interactive ones.

library(vegabrite)
vl_chart() %>%
   vl_add_data(values = mtcars) %>%
   vl_mark_point() %>%
   vl_encode_x("wt") %>%
   vl_encode_y("mpg")

vl_chart() %>%
  vl_add_data(url = "https://vega.github.io/vega-editor/app/data/population.json") %>%
  vl_calculate(calculate = "datum.sex == 2 ? 'Female' : 'Male'", 
               as = "gender") %>%
  vl_filter("datum.year == 2000") %>%
  vl_encode(x = "age:O", y = "people:Q", color = "gender:N") %>%
  vl_stack_y("normalize") %>%
  vl_aggregate_y("sum") %>%
  vl_axis_y(title = "population") %>%
  vl_mark_bar()