Area layer

Adds a filled area layer. With y mapped this is a classic (optionally stacked) area chart via geom_area; with ymin/ymax mapped instead it becomes an interval band via geom_ribbon — confidence bands, min/max envelopes, or any "area between two curves" view (Vega-Lite's area covers both, as does G2).

Usage

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

Arguments

plot

A plotit object

mapping

Optional new aesthetics

data

Optional data for this layer

position

Position adjustment.

...

Other arguments passed to geom_area (or geom_ribbon when ymin/ymax drive the layer)

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

Vega-Lite: Area / Band

AntV G2: Area

Examples

plotit(ggplot2::economics, encode(x = date, y = unemploy)) |>
  mark_area(alpha = 0.5)


# interval band: smooth fit with 95% confidence envelope
fit <- stats::loess(mpg ~ wt, data = mtcars)
band <- data.frame(
  wt = mtcars$wt,
  fit = stats::predict(fit),
  se = stats::predict(fit, se = TRUE)$se.fit
)
band$lo <- band$fit - 1.96 * band$se
band$hi <- band$fit + 1.96 * band$se
plotit(band, encode(x = wt, ymin = lo, ymax = hi)) |>
  mark_area(alpha = 0.2, fill = "#4E79A7") |>
  mark_line(mapping = encode(x = wt, y = fit))