Annotate a reference line

Draws a reference line within the panel, with style defaults taken from the axis.line element of the set theme.

Usage

reference_line(
  ...,
  xintercept = NULL,
  yintercept = NULL,
  colour = NULL,
  linewidth = NULL,
  linetype = "dashed"
)

Arguments

...

Not used. Forces named arguments.

xintercept

Draw a vertical reference line at this x position.

yintercept

Draw a horizontal reference line at this y position.

colour

Inherits from axis.line in the set theme.

linewidth

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

linetype

Defaults to "dashed".

Value

A list of ggplot2 annotation layers.

See also

axis_line(), axis_ticks(), axis_text(), axis_bracket(), 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"))