Paul Tol's Sequential Colour Schemes for ggplot2 and ggraphSource:
Provides sequential colour scales from Paul Tol's Colour Schemes.
Arguments passed to
logicalscalar. Should the resulting vector of colors be reversed?
numericvector specifying the fraction of the scheme's colour domain to keep.
characterstring or vector of character strings listing the name(s) of the aesthetic(s) that this scale works with.
logicalscalar: should the colour scheme be used as a discrete scale? If
TRUE, it is a departure from Paul Tol's recommendations and likely a very poor use of colour.
A continuous scale.
|Palette||Max. colors||NA value|
If more colors than defined are needed from a given scheme, the colour
coordinates are linearly interpolated to provide a continuous version of the
scheme, with the exception of the
discrete rainbow scheme (see below).
Note that the default colour for
NA can be overridden by passing
a value to
Rainbow colour scheme
As a general rule, ordered data should not be represented using a rainbow scheme. There are three main arguments against such use (Tol 2018):
The spectral order of visible light carries no inherent magnitude message.
Some bands of almost constant hue with sharp transitions between them, can be perceived as jumps in the data.
Colour-blind people have difficulty distinguishing some colours of the rainbow.
If such use cannot be avoided, Paul Tol's technical note provides two colour schemes that are reasonably clear in colour-blind vision. To remain colour-blind safe, these two schemes must comply with the following conditions:
This scheme must not be interpolated.
This scheme does not have to be used over the full range.
Tol, P. (2018). Colour Schemes. SRON. Technical Note No. SRON/EPS/TN/09-002, issue 3.1. URL: https://personal.sron.nl/~pault/data/colourschemes.pdf
Other colour-blind safe colour schemes:
data(faithfuld, package = "ggplot2") ggplot2::ggplot(faithfuld, ggplot2::aes(waiting, eruptions, fill = density)) + ggplot2::geom_raster() + scale_fill_YlOrBr() ggplot2::ggplot(faithfuld, ggplot2::aes(waiting, eruptions, fill = density)) + ggplot2::geom_raster() + scale_fill_iridescent(reverse = TRUE) ggplot2::ggplot(faithfuld, ggplot2::aes(waiting, eruptions, fill = density)) + ggplot2::geom_raster() + scale_fill_smoothrainbow(range = c(0.25, 1))