colorspace: divergingx_hcl – R documentation

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divergingx_hcl

(More) Flexible Diverging HCL Palettes

Description

Diverging HCL color palettes generated through combination of two fully flexible (and possibly unbalanced) multi-hue sequential palettes.

Usage

divergingx_hcl(
  n,
  palette = "Geyser",
  ...,
  fixup = TRUE,
  alpha = 1,
  rev = FALSE,
  h1,
  h2,
  h3,
  c1,
  c2,
  c3,
  l1,
  l2,
  l3,
  p1,
  p2,
  p3,
  p4,
  cmax1,
  cmax2
)

divergingx_palettes(palette = NULL, plot = FALSE, n = 7L, ...)

Arguments

`n`	the number of colors (>= 1) to be in the palette.
`palette`	character with the name (see details).
`...`	arguments passed to `hex`.
`fixup`	logical. Should the color be corrected to a valid RGB value?
`alpha`	numeric vector of values in the range `[0, 1]` for alpha transparency channel (0 means transparent and 1 means opaque).
`rev`	logical. Should the palette be reversed?
`h1`	numeric. Starting hue coordinate.
`h2`	numeric. Center hue coordinate.
`h3`	numeric. Ending hue coordinate.
`c1`	numeric. Chroma coordinate corresponding to `h1`.
`c2`	numeric. Chroma coordinate corresponding to `h2` (if `NA`, set to 0).
`c3`	numeric. Chroma coordinate corresponding to `h3`.
`l1`	numeric. Luminance coordinate corresponding to `h1`.
`l2`	numeric. Luminance coordinate corresponding to `h2`.
`l3`	numeric. Luminance coordinate corresponding to `h3` (if `NA`, `l1` is used).
`p1`	numeric. Power parameter for chroma coordinates in first sequential palette.
`p2`	numeric. Power parameter for luminance coordinates in first sequential palette (if `NA`, `p1` is used).
`p3`	numeric. Power parameter for chroma coordinates in second sequential palette (if `NA`, `p1` is used).
`p4`	numeric. Power parameter for luminance coordinates in second sequential palette (if `NA`, `p3` is used).
`cmax1`	numeric. Maximum chroma coordinate in first sequential palette (not used if `NA`).
`cmax2`	numeric. Maximum chroma coordinate in second sequential palette (if `NA`, `cmax1` is used).
`plot`	logical. Should the selected HCL color palettes be visualized?

Details

The divergingx_hcl function simply calls sequential_hcl twice with a prespecified set of hue, chroma, and luminance parameters. This is similar to diverging_hcl but allows for more flexibility: diverging_hcl employs two single-hue sequential palettes, always uses zero chroma for the neutral/central color, and restricts the chroma/luminance path to be the same in both “arms” of the palette. In contrast, divergingx_hcl relaxes this to two full multi-hue palettes that can thus go through a non-gray neutral color (typically light yellow). Consequently, the chroma/luminance paths can be rather unbalanced between the two arms.

With this additional flexibility various diverging palettes suggested by https://ColorBrewer2.org/ and CARTO (https://carto.com/carto-colors/), can be emulated along with the Zissou 1 palette from wesanderson, Cividis from viridis, and Roma from scico.

Available CARTO palettes: ArmyRose, Earth, Fall, Geyser, TealRose, Temps, and Tropic (with Tropic also available in diverging_hcl).

Available ColorBrewer.org palettes: PuOr, RdBu, RdGy, PiYG, PRGn, BrBG, RdYlBu, RdYlGn, Spectral.

Value

A character vector with (s)RGB codings of the colors in the palette.

References

Zeileis A, Fisher JC, Hornik K, Ihaka R, McWhite CD, Murrell P, Stauffer R, Wilke CO (2020). “colorspace: A Toolbox for Manipulating and Assessing Colors and Palettes.” Journal of Statistical Software, 96(1), 1–49. doi: 10.18637/jss.v096.i01

Examples

## show emulated CARTO/ColorBrewer.org palettes
divergingx_palettes(plot = TRUE)

## compared to diverging_hcl() the diverging CARTO palettes are typically warmer
## but also less balanced with respect to chroma/luminance, see e.g.,
specplot(divergingx_hcl(7, "ArmyRose"))

colorspace

A Toolbox for Manipulating and Assessing Colors and Palettes

v2.0-1

BSD_3_clause + file LICENSE

Authors

Ross Ihaka [aut], Paul Murrell [aut] (<https://orcid.org/0000-0002-3224-8858>), Kurt Hornik [aut] (<https://orcid.org/0000-0003-4198-9911>), Jason C. Fisher [aut] (<https://orcid.org/0000-0001-9032-8912>), Reto Stauffer [aut] (<https://orcid.org/0000-0002-3798-5507>), Claus O. Wilke [aut] (<https://orcid.org/0000-0002-7470-9261>), Claire D. McWhite [aut] (<https://orcid.org/0000-0001-7346-3047>), Achim Zeileis [aut, cre] (<https://orcid.org/0000-0003-0918-3766>)

Initial release

2021-05-03