Continuous and binned colour scales

Source: R/scale-colour.r, R/zxx.r

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.

scale_colour_continuous(..., type = getOption("ggplot2.continuous.colour"))

scale_fill_continuous(..., type = getOption("ggplot2.continuous.fill"))

scale_colour_binned(..., type = getOption("ggplot2.binned.colour"))

scale_fill_binned(..., type = getOption("ggplot2.binned.fill"))

Arguments

...

Additional parameters passed on to the scale type
type

One of the following:

  • "gradient" (the default)

  • "viridis"

  • A function that returns a continuous colour scale.

Details

All these colour scales use the options() mechanism to determine default settings. Continuous colour scales default to the values of the ggplot2.continuous.colour and ggplot2.continuous.fill options, and binned colour scales default to the values of the ggplot2.binned.colour and ggplot2.binned.fill options. These option values default to "gradient", which means that the scale functions actually used are scale_colour_gradient()/scale_fill_gradient() for continuous scales and scale_colour_steps()/scale_fill_steps() for binned scales. Alternative option values are "viridis" or a different scale function. See description of the type argument for details.

Note that the binned colour scales will use the settings of ggplot2.continuous.colour and ggplot2.continuous.fill as fallback, respectively, if ggplot2.binned.colour or ggplot2.binned.fill are not set.

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 visulizations. 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()

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

Examples

v <- ggplot(faithfuld, aes(waiting, eruptions, fill = density)) +
geom_tile()
v


v + scale_fill_continuous(type = "gradient")

v + scale_fill_continuous(type = "viridis")


# The above are equivalent to
v + scale_fill_gradient()

v + scale_fill_viridis_c()


# To make a binned version of this plot
v + scale_fill_binned(type = "viridis")


# Set a different default scale using the options
# mechanism
tmp <- getOption("ggplot2.continuous.fill") # store current setting
options(ggplot2.continuous.fill = scale_fill_distiller)
v

options(ggplot2.continuous.fill = tmp) # restore previous setting