stat_color: Calculate colours from wavelength.

In ggspectra: Extensions to 'ggplot2' for Radiation Spectra

Calculate colours from wavelength.

Description

stat_color computes colour definitions according to human vision.

Usage

stat_color(
  mapping = NULL,
  data = NULL,
  geom = "point",
  position = "identity",
  ...,
  chroma.type = "CMF",
  x.colour.transform = function(x) {
     x
 },
  na.rm = FALSE,
  show.legend = FALSE,
  inherit.aes = TRUE
)

Arguments

mapping	The aesthetic mapping, usually constructed with aes or aes_. Only needs to be set at the layer level if you are overriding the plot defaults.
data	A layer specific dataset - only needed if you want to override the plot defaults.
geom	The geometric object to use display the data
position	The position adjustment to use for overlapping points on this layer
...	other arguments passed on to layer. This can include aesthetics whose values you want to set, not map. See layer for more details.
chroma.type	character one of "CMF" (color matching function) or "CC" (color coordinates) or a chroma_spct object.
x.colour.transform	function Applied to x values before computing matching colours.
na.rm	a logical value indicating whether NA values should be stripped before the computation proceeds.
show.legend	logical. Should this layer be included in the legends? NA, the default, includes if any aesthetics are mapped. FALSE never includes, and TRUE always includes.
inherit.aes	If FALSE, overrides the default aesthetics, rather than combining with them. This is most useful for helper functions that define both data and aesthetics and shouldn't inherit behaviour from the default plot specification, e.g. borders.

Details

For each row in data a colour definition is computed assuming that after transformation with x.colour.transform() the values in x are wavelengths expressed in nanometres.

Value

The original data frame with variable wl.color containing colour definitions added.

Computed variable

wl.color

color corresponding to x-value giving wavelength in nanometres.

Default aesthetics

Set by the statistic and available to geoms.

color

after_stat(wl.color)

fill

after_stat(wl.color)

Required aesthetics

Required by the statistic and need to be set with aes().

x

numeric, wavelength in nanometres

y

numeric, a spectral quantity

See Also

color_of, which is used internally.

Other stats functions: stat_find_qtys(), stat_find_wls(), stat_label_peaks(), stat_peaks(), stat_spikes(), stat_wb_box(), stat_wb_column(), stat_wb_contribution(), stat_wb_hbar(), stat_wb_irrad(), stat_wb_label(), stat_wb_mean(), stat_wb_relative(), stat_wb_sirrad(), stat_wb_total(), stat_wl_strip(), stat_wl_summary()

Examples

ggplot(sun.spct) +
  geom_line() +
  stat_color() +
  scale_color_identity()

ggplot(sun.spct) +
  geom_line() +
  stat_color(x.colour.transform = function(x) {-x}) +
  scale_color_identity() +
  scale_x_reverse()

ggplot(sun.spct) +
  geom_line() +
  stat_color(x.colour.transform = function(x) {10^x}) +
  scale_color_identity() +
  scale_x_log10()

ggspectra documentation built on March 18, 2026, 1:06 a.m.