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Annotate an axis line

Source: R/axis.R
annotate_axis_line.Rd

Draws a line with style defaults taken from the axis.line element of the set theme. Typically used to place a line along an axis edge or as an interior reference line, with optional xmin/xmax/ymin/ymax to draw a partial line. Lines along or outside the panel boundary requires coord_cartesian(clip = "off").

Usage

annotate_axis_line(
  ...,
  position = NULL,
  x = NULL,
  y = NULL,
  xmin = NULL,
  xmax = NULL,
  ymin = NULL,
  ymax = NULL,
  xend = NULL,
  yend = NULL,
  curvature = NULL,
  angle = 90,
  ncp = 5,
  colour = NULL,
  linewidth = NULL,
  linetype = NULL,
  element_to = "keep"
)

Arguments

...

Not used. Allows trailing commas and named-argument style calls.

position

One of "top", "bottom", "left", or "right". Axis line mode only.

x

In axis line mode, a single x value for a vertical line. In segment/curve mode, the x start position. Use I() for normalized coordinates (0-1).

y

In axis line mode, a single y value for a horizontal line. In segment/curve mode, the y start position. Use I() for normalized coordinates (0-1).

xmin, xmax

Start and end x positions for a horizontal axis line. Use I() for normalized coordinates (0-1). Axis line mode only.

ymin, ymax

Start and end y positions for a vertical axis line. Use I() for normalized coordinates (0-1). Axis line mode only.

xend, yend

End position of the segment or curve. Providing all of x, y, xend, yend triggers segment/curve mode.

curvature

Amount of curvature. Negative curves left, positive curves right, zero is straight. NULL (default) draws a straight segment.

angle

Skew angle of curve control points (0-180). Used only when curvature is non-NULL. Defaults to 90.

ncp

Number of curve control points. Higher values give smoother curves. Used only when curvature is non-NULL. Defaults to 5.

colour

Inherits from axis.line in the set theme.

linewidth

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

linetype

Inherits from axis.line in the set theme.

element_to

One of "keep", "transparent", or "blank". Controls whether the native theme axis line is suppressed. Defaults to "keep". Axis line mode only.

Value

A list of ggplot2 annotation layers and theme elements.

Details

Can also draw a straight segment or curve between two arbitrary points when x, y, xend, and yend are all provided.

Examples

library(ggplot2)

set_theme(theme_classic())

p <- ggplot(mtcars, aes(wt, mpg)) +
  geom_point() +
  coord_cartesian(clip = "off")

# Replace the bottom axis line
p + annotate_axis_line(position = "bottom", element_to = "transparent")


# Partial bottom axis between x = 2 and x = 4
p + annotate_axis_line(position = "bottom", xmin = 2, xmax = 4, element_to = "transparent")


# Vertical rule at x = 3.5
p + annotate_axis_line(x = 3.5)


# Straight line between two data points
p + annotate_axis_line(x = 2, y = 15, xend = 5, yend = 30)


# Curved line between two data points
p + annotate_axis_line(x = 2, y = 15, xend = 5, yend = 30, curvature = 0.3)