Back in September 2022 I submitted {PrettyCols}, an R package containing aesthetically pleasing colour palettes, to CRAN. If you missed it, you can read the blog post introducing the package!

Over a year after the last CRAN release, it was time for an update and this blog post will give you a brief overview of some of the new features and palettes! You can install {PrettyCols} using:

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install.packages("PrettyCols")

You can also install the development version from GitHub using:

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remotes::install_github("nrennie/PrettyCols")

Breaking changes

Previous versions of {PrettyCols} used the name argument in all of the {ggplot2} scale functions to define the name of the palette you wanted to use. Unfortunately, {ggplot2} uses name to define the name of the legend. This meant there was an inconsistency between {PrettyCols} and other {ggplot2} scale functions, and I wanted to fix that in this release. Now, the behaviour is more consistent.

• Change: the palette argument is now used to define the name of the colour palette you want to use.

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library(ggplot2)
ggplot(
 data = mtcars,
 mapping = aes(x = cyl, fill = as.factor(gear))
) +
 geom_bar() +
 scale_fill_pretty_d(palette = "Peppers")

For example, if you have previously scale_fill_manual(name = "Bright") to say you want to use the "Bright" palette, this will result in an error. Please use scale_fill_manual(palette = "Bright") instead. If you didn’t explicitly name the argument for the palette name, your code should still work.

Changing the legend name

To get around the problem above, earlier versions of {PrettyCols} added a legend_title argument to the scale_*_pretty_*() functions. The legend_title argument still works, but you will get a deprecation warning. To maintain consistency with other {ggplot2} scale functions, you should use name instead.

• Change: the name argument sets the legend (scale) name.

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ggplot(
 data = mtcars,
 mapping = aes(x = mpg, y = disp, colour = wt)
) +
 geom_point(size = 5) +
 scale_colour_pretty_c("Roses", name = "New Title")

Diverging scales

There were several diverging palettes already within {PrettyCols}, and in version 1.1.0 you can now use the palettes with diverging scales in {ggplot2} more easily.

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ggplot(
 data = mtcars,
 mapping = aes(x = mpg, y = disp, fill = wt)
) +
 geom_point(size = 5, pch = 21) +
 scale_fill_pretty_div(
 palette = "PurpleYellows",
 midpoint = mean(mtcars$wt)
 )

The following diverging scales functions now exist:

• scale_colour_pretty_div() and scale_color_pretty_div()
• scale_fill_pretty_div()

They work similarly to scale_*_gradient2().

More palettes!

The new release contains eight additional palettes, taking the total up to 40 palettes! You can see the complete list of available palettes by running view_all_palettes() or browsing the package vignette on available palettes.

Python support

A Python implementation of {PrettyCols} existed in previous releases, but Python support has now moved to a separate GitHub repository. See github.com/nrennie/PrettyPyCols.*

To end this post, here’s another couple of examples of these palettes being used for generative art!

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aRt::split_grid(
 col_palette = prettycols("Coast"),
 grid_col = prettycols("Coast")[3],
 n_x = 6,
 n_y = 6
)

aRt::window_boxes(
 col_palette = prettycols("Disco"),
 n_x = 20,
 n_y = 20
)

If you find that something in {PrettyCols} isn’t working, or if you’ve got an idea for more features, please raise a GitHub issue!