Getting Started

For a comprehensive introduction to Vega-Lite, please visit the its web site. An interactive tutorial to vegawidget is available at shinyapps.io.

Vega(-Lite) specifications are just text, formatted as JSON. However, in R, we can use lists to build specifications:

library("vegawidget")

spec_mtcars <-
  list(
    `$schema` = vega_schema(), # specifies Vega-Lite
    description = "An mtcars example.",
    data = list(values = mtcars),
    mark = "point",
    encoding = list(
      x = list(field = "wt", type = "quantitative"),
      y = list(field = "mpg", type = "quantitative"),
      color = list(field = "cyl", type = "nominal")
    )
  ) %>% 
  as_vegaspec()

The as_vegaspec() function is used to turn the list into a vegaspec; many of this package’s functions are built to support, and render, vegaspecs:

spec_mtcars

This package is a low-level interface to Vega-Lite and the Vega ecosystem, which has a lot of powerful capabilities, highlighted in this series of articles:

Specify using vegaspec: how to construct and render a vegaspec.
Render using vegawidget: advanced rendering options.
Extend using Shiny: how to interact with Vega charts using Shiny.
Extend using JavaScript: how to interact with Vega charts using JavaScript.
Create Images: how to create and save PNG or SVG images.
Work with Dates and Times: dates and times in Vega(-Lite) work a little differently from R.
Import into Other Packages: how to import vegawidget functions into your package, then re-export them.

To share your Vega(-Lite) creation on the Blocks website, you can use the vegablock package.

Integration with other packages

Although there is an article dedicated to this aspect of the package, it warrants further emphasis.

This package provides functions to render Vega(-Lite) specifications; although it provides some helpers, it does not provide higher-level functions to build specifications. Rather, this is left to other packages. Even though you can use its functions directly, you are invited to import and re-export them for use in your package.

Accordingly, this package offers a templating function, use_vegawidget(), to help you integrate vegawidget functions into your package. For example, it is used to import and re-export vegawidget functions for the altair package.

Known limitations

The two biggest known limitations are both associated with vegaspecs that contain datasets specified using remote URLs:

The RStudio IDE may not let you access remote URLs for security reasons. A chart that accesses remote data may not render in the IDE; it will render in a browser window.
The image functions use nodejs to create SVG strings. We are not able to configure the proxy in our node scripts, so if your computer uses a proxy to access remote data, our functions will not create the images properly.