Unique rows: stat_unique

Mix.install([
  {:giggly, path: Path.join(__DIR__, "..")},
  {:kino, "~> 0.19"}
  ])

alias Giggly.Plot

mtcars = Giggly.Datasets.mtcars()

render = fn plot ->
  plot
  |> Giggly.to_svg()
  |> IO.iodata_to_binary()
  |> Kino.Image.new(:svg)
end

About this notebook

This notebook follows the examples on ggplot2's reference page for stat_unique(), in the order the page gives them. Each example shows ggplot2's code first and then Giggly's. An example Giggly cannot draw yet keeps its ggplot2 code and names what it is waiting for, so the page is also a list of what remains.

stat_unique() removes duplicate rows before they are drawn, so marks that would fall exactly on one another are drawn once. It is usually given to a geom as stat = "unique". Giggly has none of it yet, but draws the overlapping points it is compared with. A plot is described with Giggly.Plot and drawn with Giggly.to_svg/2, which returns an SVG document. The setup cell aliases Giggly.Plot, so the cells write Plot.new/2, and defines render, which draws a plot and shows it below the cell with Kino.Image. The data in these examples is Giggly.Datasets.mtcars/0, R's mtcars: 32 cars from the 1974 Motor Trend US magazine, which the setup cell binds to mtcars, R's name for it.

Overlapping points

ggplot(mtcars, aes(vs, am)) +
  geom_point(alpha = 0.1)

vs and am are each 0 or 1, so the cars pile up at the corners, and each nearly transparent point darkens the ones beneath it.

mtcars
|> Plot.new(%{x: :vs, y: :am})
|> Plot.geom_point(alpha: 0.1)
|> render.()

One point for each distinct row

ggplot(mtcars, aes(vs, am)) +
  geom_point(alpha = 0.1, stat = "unique")

With the duplicates removed, each corner has a single faint point.

Not in Giggly yet: stat_unique() given to a geom as stat = "unique".