mpg

Fuel economy of 30 cars (small fuel-economy reference dataset).

Each row is one vehicle. Columns:

manufacturer (string).
model (string).
displ (engine displacement, litres).
cyl (number of cylinders).
class (vehicle class, e.g., "compact", "midsize", "suv").
cty (city miles per gallon).
hwy (highway miles per gallon).

The bundled literal is stored in column-store form; plot accepts either column-store or row-store input and normalises internally.

Source: subset of the mpg dataset bundled with the ggplot2 R package; see help("mpg") in R. Originally extracted from the US Environmental Protection Agency’s fuel economy data, https://fueleconomy.gov/, restricted to models with a new release every year between 1999 and 2008.

Usage

mpg

Examples

Preview the first ten entries (out of 30).

#let cols = mpg.pairs()
#let cell(v) = if v == none { text(fill: gray, [_none_]) } else { [#v] }
#table(
  columns: cols.len(),
  align: center + horizon,
  inset: 5pt,
  stroke: 0.5pt,
  ..cols.map(p => strong(raw(p.at(0)))),
  ..range(10).map(i => cols.map(p => cell(p.at(1).at(i)))).flatten(),
)

Highway mpg vs engine displacement, filled by vehicle class.

#plot(
  data: mpg,
  mapping: aes(x: "displ", y: "hwy", fill: "class"),
  layers: (geom-point(size: 3pt),),
  width: 11cm,
  height: 7cm,
)

Facet by class and add a linear smoother per panel to compare per-class trends.

#plot(
  data: mpg,
  mapping: aes(x: "displ", y: "hwy"),
  layers: (
    geom-point(size: 2pt),
    geom-smooth(method: "lm", se: false),
  ),
  facet: facet-wrap("class", ncolumn: 3),
  width: 12cm,
  height: 7cm,
)