
Paul Tol's smooth rainbow Sequential Colour Scheme
Source:R/scale_colour_tol.R
scale_tol_smoothrainbow.Rd
Paul Tol's smooth rainbow Sequential Colour Scheme
Usage
scale_colour_smoothrainbow(
...,
reverse = FALSE,
range = c(0, 1),
discrete = FALSE,
aesthetics = "colour"
)
scale_color_smoothrainbow(
...,
reverse = FALSE,
range = c(0, 1),
discrete = FALSE,
aesthetics = "colour"
)
scale_fill_smoothrainbow(
...,
reverse = FALSE,
range = c(0, 1),
discrete = FALSE,
aesthetics = "fill"
)
scale_edge_colour_smoothrainbow(
...,
reverse = FALSE,
range = c(0, 1),
discrete = FALSE,
aesthetics = "edge_colour"
)
scale_edge_color_smoothrainbow(
...,
reverse = FALSE,
range = c(0, 1),
discrete = FALSE,
aesthetics = "edge_colour"
)
scale_edge_fill_smoothrainbow(
...,
reverse = FALSE,
range = c(0, 1),
discrete = FALSE,
aesthetics = "edge_fill"
)
Arguments
- ...
Arguments passed to
ggplot2::continuous_scale()
.- reverse
A
logical
scalar. Should the resulting vector of colors be reversed?- range
A length-two
numeric
vector specifying the fraction of the scheme's colour domain to keep.- discrete
A
logical
scalar: should the colour scheme be used as a discrete scale? IfTRUE
, it is a departure from Paul Tol's recommendations and likely a very poor use of colour.- aesthetics
A
character
string or vector of character strings listing the name(s) of the aesthetic(s) that this scale works with.
Value
A continuous scale.
Interpolation
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 ggplot2::continuous_scale()
.
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:
discreterainbow
This scheme must not be interpolated.
smoothrainbow
This scheme does not have to be used over the full range.
References
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
See also
Other sequential colour schemes:
scale_crameri_acton
,
scale_crameri_bamako
,
scale_crameri_batlowK
,
scale_crameri_batlowW
,
scale_crameri_batlow
,
scale_crameri_bilbao
,
scale_crameri_buda
,
scale_crameri_davos
,
scale_crameri_devon
,
scale_crameri_grayC
,
scale_crameri_hawaii
,
scale_crameri_imola
,
scale_crameri_lajolla
,
scale_crameri_lapaz
,
scale_crameri_nuuk
,
scale_crameri_oslo
,
scale_crameri_tokyo
,
scale_crameri_turku
,
scale_tol_YlOrBr
,
scale_tol_discreterainbow
,
scale_tol_iridescent
Other Paul Tol's colour schemes:
scale_tol_BuRd
,
scale_tol_PRGn
,
scale_tol_YlOrBr
,
scale_tol_bright
,
scale_tol_dark
,
scale_tol_discreterainbow
,
scale_tol_highcontrast
,
scale_tol_iridescent
,
scale_tol_light
,
scale_tol_mediumcontrast
,
scale_tol_muted
,
scale_tol_pale
,
scale_tol_sunset
,
scale_tol_vibrant
Examples
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))