Binned box plot

The box mark expects a quantitative dimension (for its extent, here, y, representing price), and optionally an ordinal dimension. The example below uses the [scale interval option](plot to convert carats (a quantitative dimension) into a usable ordinal dimension, on fx. If you are interested in ways to make this easier, please upvote #1330.

Plot.plot({
  marginLeft: 60,
  y: {
    grid: true,
    label: "↑ Price"
  },
  fx: {
    interval: 0.5,
    label: "Carats →",
    labelAnchor: "right",
    tickFormat: (x) => x.toFixed(1)
  },
  marks: [
    Plot.ruleY([0]),
    Plot.boxY(diamonds, {fx: "carat", y: "price"})
  ]
})

const diamonds = FileAttachment("data/diamonds.csv").csv({typed: true}).then(display);