Colour rings and arcs

Similar to guide_colourbar(), this guide displays continuous colour or fill aesthetics. Instead of a bar, the gradient in shown in a ring or arc, which can be convenient for cyclical palettes such as some provided in the scico package.

Usage

guide_colring(
  title = waiver(),
  key = "auto",
  start = 0,
  end = NULL,
  outer_guide = "axis_base",
  inner_guide = "axis_base",
  nbin = 300,
  reverse = FALSE,
  show_labels = "outer",
  theme = NULL,
  vanilla = TRUE,
  position = waiver(),
  available_aes = c("colour", "fill"),
  ...
)

Arguments

title

A <character[1]> or <expression[1]> indicating the title of the guide. If NULL, the title is not shown. The default, waiver(), takes the name of the scale object or the name specified in labs() as the title.

key

A standard key specification. Defaults to key_auto().

start, end

A <numeric[1]> in radians specifying the offset of the starting and end points from 12 o'clock. The NULL default for end, internally defaults to start + 2 * pi.

outer_guide, inner_guide

Guides to display on the outside and inside of the colour ring. Each guide can be specified using one of the following:

• A <Guide> class object.

• A <function> that returns a <Guide> class object.

• A <character> naming such function, without the guide_ or primitive_ prefix.

nbin

A positive <integer[1]> determining how many colours to display.

reverse

A <logical[1]> whether to reverse continuous guides. If TRUE, guides like colour bars are flipped. If FALSE (default), the original order is maintained.

show_labels

A <character[1]> indicating for which guide labels should be shown. Can be one of "outer" (default), "inner", "both" or "none". Note that labels can only be omitted if the related guide has a label suppression mechanism.

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.

vanilla

A <logical[1]> whether to have the default style match the vanilla guide_colourbar() (TRUE) or take the theme verbatim (FALSE).

position

A <character[1]> giving the location of the guide. Can be one of "top", "bottom", "left" or "right".

available_aes

A <character> vector listing the aesthetics for which this guide can be build.

...

Arguments forwarded to the outer_guide and inner_guide if provided as functions or strings.

Value

A <Guide> object.

See also

Other standalone guides: guide_axis_base(), guide_axis_nested(), guide_colbar(), guide_colsteps(), guide_legend_base(), guide_legend_cross(), guide_legend_group()

Examples

# Rings works best with a cyclical palette
my_pal <- c("black", "tomato", "white", "dodgerblue", "black")

p <- ggplot(mpg, aes(displ, hwy, colour = cty)) +
  geom_point() +
  scale_colour_gradientn(colours = my_pal)

# Standard colour ring
p + guides(colour = "colring")


# As an arc
p + guides(colour = guide_colring(
  start = 1.25 * pi, end = 2.75 * pi
))


# Removing the inner tick marks
p + guides(colour = guide_colring(inner_guide = "none"))


# Include labels on the inner axis
p + guides(colour = guide_colring(show_labels = "both"))


# Passing an argument to inner/outer guides
p + guides(colour = guide_colring(angle = 0))