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Annotate an axis bracket

Source: R/axis-bracket.R
axis_bracket.Rd

Draws a bracket spanning min(breaks) to max(breaks) along an axis edge or at a floating data position. The bar uses the same rendering path as axis_line(); the caps use the same path as axis_ticks(). Requires coord_cartesian(clip = "off").

Usage

axis_bracket(
  ...,
  position = NULL,
  xintercept = NULL,
  yintercept = NULL,
  breaks,
  colour = NULL,
  linewidth = NULL,
  linetype = NULL,
  length = ggplot2::rel(1)
)

Arguments

...

Not used. Forces named arguments.

position

One of "top", "bottom", "left", or "right". Inferred from xintercept or yintercept if not provided.

xintercept

For "left"/"right" axes: float the bracket to this x position in data coordinates instead of the panel edge.

yintercept

For "top"/"bottom" axes: float the bracket to this y position in data coordinates instead of the panel edge.

breaks

A numeric vector of length >= 2. The bar spans min(breaks) to max(breaks); caps are drawn at every break value.

colour

Inherits from axis.ticks in the set theme (falling back through axis.line and line).

linewidth

Inherits from axis.ticks in the set theme. Supports rel().

linetype

Inherits from axis.ticks in the set theme.

length

Length of the bracket caps as a grid unit. Supports rel(). Negative values flip the cap direction. Defaults to rel(1) (outward at theme tick length).

Value

A list of ggplot2 annotation layers.

See also

axis_line(), axis_ticks(), axis_text(), reference_line(), panel_shade(), sec_axis_text()

Examples

library(ggplot2)
library(dplyr)

set_theme(
  ggrefine::theme_grey(
    panel_heights = rep(unit(50, "mm"), 100),
    panel_widths = rep(unit(75, "mm"), 100),
  )
)

mtcars |>
  ggplot(aes(x = wt, y = mpg, colour = as.factor(gear), fill = as.factor(gear))) +
  scale_colour_discrete(palette = blends::multiply(get_theme()$palette.colour.discrete)) +
  #clip = "off" is required for axis_text, axis_ticks and axis_bracket
  coord_cartesian(clip = "off") +
  #reference lines and shade
  ggscribe::reference_line(xintercept = 2.4) +
  ggscribe::reference_line(yintercept = 12)  +
  ggscribe::panel_shade(
    xmin = 4,
    xmax = 5,
  ) +
  #top axis
  scale_x_continuous(
    sec.axis = ggscribe::sec_axis_text(
      breaks = c(mean(c(4, 5))),
      labels = c("Range"),
      guide = ggscribe::guide_sec_axis_text(
        angle = 90,
      )
    )
  ) +
  ggscribe::axis_bracket(
    position = "top",
    breaks = c(4, 5),
  ) +
  ggscribe::axis_text(
    position = "top",
    breaks = c(2.4),
    labels = c("Threshold"),
  ) +
  #right axis
  ggscribe::axis_text(
    position = "right",
    breaks = 12,
    labels = "Threshold",
  ) +
  #'geom
  geom_point() +
  #annotations fit plot
  theme(plot.background = element_rect(colour = "grey92"))