Continuous and binned colour scales

The scales scale_colour_continuous() and scale_fill_continuous() are the default colour scales ggplot2 uses when continuous data values are mapped onto the colour or fill aesthetics, respectively. The scales scale_colour_binned() and scale_fill_binned() are equivalent scale functions that assign discrete color bins to the continuous values instead of using a continuous color spectrum.

Usage

scale_colour_continuous(
  ...,
  palette = NULL,
  aesthetics = "colour",
  guide = "colourbar",
  na.value = "grey50",
  type = getOption("ggplot2.continuous.colour")
)

scale_fill_continuous(
  ...,
  palette = NULL,
  aesthetics = "fill",
  guide = "colourbar",
  na.value = "grey50",
  type = getOption("ggplot2.continuous.fill")
)

scale_colour_binned(
  ...,
  palette = NULL,
  aesthetics = "colour",
  guide = "coloursteps",
  na.value = "grey50",
  type = getOption("ggplot2.binned.colour")
)

scale_fill_binned(
  ...,
  palette = NULL,
  aesthetics = "fill",
  guide = "coloursteps",
  na.value = "grey50",
  type = getOption("ggplot2.binned.fill")
)

Arguments

...

Additional parameters passed on to the scale type

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 numeric vector with values between 0 and 1 returns the corresponding output values.

aesthetics

The names of the aesthetics that this scale works with.

guide

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

na.value

Missing values will be replaced with this value.

type

One of the following:

• "gradient" (the default)

• "viridis"

• A function that returns a continuous colour scale.

Details

: The mechanism of setting defaults via options() is superseded by theme settings. The preferred method to change the default palette of scales is via the theme, for example: theme(palette.colour.continuous = scales::pal_viridis()). The ggplot2.continuous.colour and ggplot2.continuous.fill options could be used to set default continuous scales and ggplot2.binned.colour and ggplot2.binned.fill options to set default binned scales.

These scale functions are meant to provide simple defaults. If you want to manually set the colors of a scale, consider using scale_colour_gradient() or scale_colour_steps().

Color Blindness

Many color palettes derived from RGB combinations (like the "rainbow" color palette) are not suitable to support all viewers, especially those with color vision deficiencies. Using viridis type, which is perceptually uniform in both colour and black-and-white display is an easy option to ensure good perceptive properties of your visualizations. The colorspace package offers functionalities

• to generate color palettes with good perceptive properties,

• to analyse a given color palette, like emulating color blindness,

• and to modify a given color palette for better perceptivity.

For more information on color vision deficiencies and suitable color choices see the paper on the colorspace package and references therein.

See also

scale_colour_gradient(), scale_colour_viridis_c(), scale_colour_steps(), scale_colour_viridis_b(), scale_fill_gradient(), scale_fill_viridis_c(), scale_fill_steps(), and scale_fill_viridis_b()

The documentation on colour aesthetics.

The continuous colour scales section of the online ggplot2 book.

Other colour scales: scale_alpha(), scale_colour_brewer(), 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 = cty)) +
  geom_point()

# You can use the scale to give a palette directly
p + scale_colour_continuous(palette = c("#FEE0D2", "#FC9272", "#DE2D26"))


# The default colours are encoded into the theme
p + theme(palette.colour.continuous = c("#DEEBF7", "#9ECAE1", "#3182BD"))


# You can globally set default colour palette via the theme
old <- update_theme(palette.colour.continuous = c("#E5F5E0", "#A1D99B", "#31A354"))

# Plot now shows new global default
p


# The default binned colour scale uses the continuous palette
p + scale_colour_binned() +
  theme(palette.colour.continuous = c("#EFEDF5", "#BCBDDC", "#756BB1"))


# Restoring the previous theme
theme_set(old)