rMosaic

R bindings for the Mosaic declarative visualization framework from UW IDL. Define linked, interactive plots from R or Shiny — brushing, cross-filtering, pan/zoom, and selection — backed by DuckDB for high-performance querying. Specs can be written as JSON, YAML, or inline ESM/JavaScript.

The Mosaic JavaScript libraries (v0.21.1) and a DuckDB-WASM connector are bundled inside the package under inst/htmlwidgets/, so the widget renders without network access.

Installation

Once on CRAN:

install.packages("rMosaic")

Development version from GitHub:

# install.packages("remotes")
remotes::install_github("TiRizvanov/rMosaic")

Quick start

library(rMosaic)

df <- data.frame(
  x   = rnorm(200),
  y   = rnorm(200),
  grp = sample(LETTERS[1:3], 200, replace = TRUE)
)

spec <- '{
  "meta": { "title": "rMosaic demo" },
  "data": { "df": {} },
  "plot": [{
    "mark": "dot",
    "data": { "from": "df" },
    "x": "x", "y": "y", "fill": "grp"
  }],
  "width": 600, "height": 400
}'

runMosaicApp(
  spec     = spec,
  specType = "json",
  data     = list(df = df),
  title    = "rMosaic demo"
)

mosaic() accepts specs as an R list, a JSON or YAML character string, a file path (.json, .yaml, .js, .mjs), or an inline ESM module via specType = "esm".

Shiny integration

library(shiny)
library(rMosaic)

ui <- fluidPage(
  mosaicOutput("vis", width = "100%", height = "600px")
)

server <- function(input, output, session) {
  output$vis <- renderMosaic({
    mosaic(spec = spec, specType = "json", data = list(df = df))
  })
}

shinyApp(ui, server)

Exporting selections back to R

runMosaicExport() (and runMosaicWithExport()) launch the widget with an Import Selection button that pulls the current brush back into R as a data.frame:

runMosaicExport(spec = spec, specType = "json", data = list(df = df))

Learning more

The package ships several vignettes that walk through real-world dashboards:

Vignette	Topic
getting-started	Core API and the spec lifecycle
format-json, format-esm	Spec format options
dynamic-rendering	Pan/zoom with on-the-fly binning
taxi-crossfilter	Multi-view dashboard, 1M+ rows
athletes-dashboard	Tables and linked selections
gaia-stars	Astronomy dataset, 5M points
protein-design-explorer	Marginal histograms, raster, and table

Open any of them with, e.g., vignette("getting-started", package = "rMosaic").

Contributing

Issues and pull requests are welcome on GitHub. Please report bugs to the package maintainer listed in DESCRIPTION.

License

MIT — see LICENSE for the full text, including the third-party Mosaic license bundled with the JavaScript assets.

Acknowledgements

Developed in the Dries Lab at Boston University. Funding support was provided by the Dries Lab and the Boston University Undergraduate Research Opportunities Program (UROP).