VegaLite.param

You're seeing just the function param, go back to VegaLite module for more information.

Specs

param(t(), String.t(), keyword()) :: t()

Adds a parameter to the specification.

Parameters are the basic building blocks for introducing interactions to graphics.

All provided options are converted to parameter properties.

Examples

Vl.new()
|> Vl.data_from_values(...)
|> Vl.concat([
  Vl.new()
  # Define a parameter named "brush", whose value is a user-selected interval on the x axis
  |> Vl.param("brush", select: [type: :interval, encodings: [:x]])
  |> Vl.mark(:area)
  |> Vl.encode_field(:x, "date", type: :temporal)
  |> ...,
  Vl.new()
  |> Vl.mark(:area)
  # Use the "brush" parameter value to limit the domain of this view
  |> Vl.encode_field(:x, "date", type: :temporal, scale: [domain: [param: "brush"]])
  |> ...
])

See the docs for more details.