Quantile-quantile points layer — mark

Adds sample quantiles against theoretical (or another sample's) quantiles – the classic normality check. Map x to the sample; y is optional (another sample for two-sample QQ). Add a reference line with mark_qq_line().

Usage

mark_qq(
  plot,
  mapping = NULL,
  data = NULL,
  position = NULL,
  ...,
  distribution = "norm",
  rasterize = FALSE,
  rasterize_dpi = 300,
  rasterize_dev = "cairo"
)

Arguments

plot: A plotit object
mapping: Optional new aesthetics (x required, y optional)
data: Optional data for this layer
position: Position adjustment.
...: Other arguments passed to geom_qq (e.g. dparams)
distribution: Theoretical distribution function without the q prefix ("norm" default); any q* function works: "norm", "unif", "exp", "lnorm", ...
rasterize: If TRUE, rasterize via ggrastr::rasterise().
rasterize_dpi: DPI for rasterization (default 300).
rasterize_dev: Graphics device for rasterization (default "cairo").

Value

Modified plotit object

References

Observable Plot: Plot.qq

Examples

ecdf_data <- data.frame(eruptions = faithful$eruptions)
plotit(ecdf_data, encode(x = eruptions)) |>
  mark_qq() |>
  mark_qq_line()


# two-sample QQ against an exponential reference
set.seed(42)
df <- data.frame(value = rexp(200))
plotit(df, encode(x = value)) |>
  mark_qq(distribution = "exp") |>
  mark_qq_line(distribution = "exp")