gizmo_barcap: Guide gizmo: capped colour bar

In legendry: Extended Legends and Axes for 'ggplot2'

Guide gizmo: capped colour bar

Description

This guide displays a colour bar with optional caps at either ends of the bar.

Usage

gizmo_barcap(
  key = "sequence",
  shape = "triangle",
  size = NULL,
  show = NA,
  alpha = NA,
  oob = "keep",
  theme = NULL,
  position = waiver(),
  direction = NULL
)

Arguments

key	A sequence key specification. Defaults to key_sequence(n = 15). Changing the argument to key_sequence() is fine, but changing the key type is not advised.
shape	A cap specification by providing one of the following: A cap ⁠<function>⁠, such as cap_triangle(). A ⁠<character[1]>⁠ naming a cap function without the 'cap_'-prefix, e.g. "round". A two column ⁠<matrix[n, 2]>⁠ giving coordinates for a cap, like those created by cap functions such as cap_arch().
size	A <unit> setting the size of the cap. When NULL (default), cap size will be proportional to the shape coordinates and the legend.key.size theme setting.
show	A ⁠<logical>⁠ to control how caps are displayed at the ends of the bar. When TRUE, caps are always displayed. When FALSE, caps are never displayed. When NA (default), caps are displayed when the data range exceed the limits. When given as ⁠<logical[2]>⁠, show[1] controls the display at the lower end and show[2] at the upper end.
alpha	A ⁠<numeric[1]>⁠ between 0 and 1 setting the colour transparency of the bar. Use NA to preserve the alpha encoded in the colour itself.
oob	An out-of-bounds handling function that affects the cap colour. Can be one of the following: A ⁠<function>⁠ like oob_squish. A ⁠<character[1]>⁠ naming such a function without the 'oob'-prefix, such as "keep".
theme	A <theme> object to style the guide individually or differently from the plot's theme settings. The theme argument in the guide overrides and is combined with the plot's theme.
position	A ⁠<character[1]>⁠ giving the location of the guide. Can be one of "top", "bottom", "left" or "right".
direction	A ⁠<character[1]>⁠ indicating the direction of the guide. Can be on of "horizontal" or "vertical".

Value

A ⁠<GizmoBarcap>⁠ object.

See Also

Other gizmos: gizmo_density(), gizmo_grob(), gizmo_histogram(), gizmo_stepcap()

Examples

# A standard plot
p <- ggplot(mpg, aes(displ, hwy, colour = cty)) +
  geom_point()

# Just a bar
p + scale_colour_viridis_c(guide = gizmo_barcap())

# Caps show up when there is data outside the limits
p + scale_colour_viridis_c(
  limits = c(10, 30),
  guide  = gizmo_barcap()
)

# The scale's out-of-bounds handler determines cap colour
p + scale_colour_viridis_c(
  limits = c(10, 30), oob = scales::oob_squish,
  guide = gizmo_barcap()
)

# Customising display of the guide
p +
  scale_colour_viridis_c(
    oob = scales::oob_squish,
    guide = gizmo_barcap(
      shape = "arch", show = c(FALSE, TRUE),
      size = unit(2, "cm"),
      theme = theme(legend.key.height = unit(4, "cm"))
    )
  ) +
  theme(
    legend.frame = element_rect(colour = "black"),
    legend.key.width = unit(0.5, "cm")
  )

legendry documentation built on Sept. 14, 2025, 5:08 p.m.