Discrete colour scales

The default discrete colour scale.

Usage

scale_colour_discrete(
  ...,
  palette = NULL,
  aesthetics = "colour",
  na.value = "grey50",
  type = getOption("ggplot2.discrete.colour")
)

scale_fill_discrete(
  ...,
  palette = NULL,
  aesthetics = "fill",
  na.value = "grey50",
  type = getOption("ggplot2.discrete.fill")
)

Arguments

...

Arguments passed on to discrete_scale

breaks

One of:

• NULL for no breaks

• waiver() for the default breaks (the scale limits)

• A character vector of breaks

• A function that takes the limits as input and returns breaks as output. Also accepts rlang lambda function notation.

limits

One of:

• NULL to use the default scale values

• A character vector that defines possible values of the scale and their order

• A function that accepts the existing (automatic) values and returns new ones. Also accepts rlang lambda function notation.

drop

Should unused factor levels be omitted from the scale? The default, TRUE, uses the levels that appear in the data; FALSE includes the levels in the factor. Please note that to display every level in a legend, the layer should use show.legend = TRUE.

na.translate

Unlike continuous scales, discrete scales can easily show missing values, and do so by default. If you want to remove missing values from a discrete scale, specify na.translate = FALSE.

name

The name of the scale. Used as the axis or legend title. If waiver(), the default, the name of the scale is taken from the first mapping used for that aesthetic. If NULL, the legend title will be omitted.

labels

One of the options below. Please note that when labels is a vector, it is highly recommended to also set the breaks argument as a vector to protect against unintended mismatches.

• NULL for no labels

• waiver() for the default labels computed by the transformation object

• A character vector giving labels (must be same length as breaks)

• An expression vector (must be the same length as breaks). See ?plotmath for details.

• A function that takes the breaks as input and returns labels as output. Also accepts rlang lambda function notation.

guide

A function used to create a guide or its name. See guides() for more information.

call

The call used to construct the scale for reporting messages.

super

The super class to use for the constructed scale

palette

One of the following:

• NULL for the default palette stored in the theme.

• a character vector of colours.

• a single string naming a palette.

• a palette function that when called with a single integer argument (the number of levels in the scale) returns the values that they should take.

aesthetics

The names of the aesthetics that this scale works with.

na.value

If na.translate = TRUE, what aesthetic value should the missing values be displayed as? Does not apply to position scales where NA is always placed at the far right.

type

The preferred mechanism for setting the default palette is by using the theme. For example: theme(palette.colour.discrete = "Okabe-Ito").

See also

discrete_scale()

The discrete colour scales section of the online ggplot2 book.

Other colour scales: scale_alpha(), scale_colour_brewer(), scale_colour_continuous(), scale_colour_gradient(), scale_colour_grey(), scale_colour_hue(), scale_colour_identity(), scale_colour_manual(), scale_colour_steps(), scale_colour_viridis_d()

Examples

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

# You can use the scale to give a palette directly
p + scale_colour_discrete(palette = scales::pal_brewer(palette = "Dark2"))


# The default colours are encoded into the theme
p + theme(palette.colour.discrete = scales::pal_grey())


# You can globally set default colour palette via the theme
old <- update_theme(palette.colour.discrete = scales::pal_viridis())

# Plot now shows new global default
p


# Restoring the previous theme
theme_set(old)