Simplify creation of style sets with defaults

[clauswilke]

I think the most common use case for style sets in practice is one where we want to use something like classic style but add a few customizations. This is a bit cumbersome with the current functions. See reprex:

library(ggplot2)
library(marquee)

colors <- c(setosa = '#93263E', virginica = '#3947A4', versicolor = '#C6A634')

# set up styling
iris_styles <- classic_style() |>
  modify_style("setosa", style(color = colors["setosa"])) |>
  modify_style("virginica", style(color = colors["virginica"])) |>
  modify_style("versicolor", style(color = colors["versicolor"]))

ggplot(iris) +
  geom_point(aes(Sepal.Length, Sepal.Width, color = Species)) +
  scale_color_manual(
    values = colors,
    guide = guide_marquee("{.setosa *I. setosa*} - {.versicolor *I. versicolor*} - {.virginica *I. virginica*}")
  )

I see at least three options to simplify this, not mutually exclusive.

1. Add a function modify_style_set()

This function would work similarly to modify_style() but enable modification of multiple styles at once. Something like this:

iris_styles <- classic_style() |>
  modify_style_set(
    setosa = style(color = colors["setosa"]),
    virginica = style(color = colors["virginica"]),
    versicolor = style(color = colors["versicolor"])
  )

2. Create style sets with default

This would modify the style_set() function to enable a default option.

iris_styles <- style_set(
  setosa = style(color = colors["setosa"]),
  virginica = style(color = colors["virginica"]),
  versicolor = style(color = colors["versicolor"]),
  .defaults = classic_style()
)

3. Provide an option to update/merge style sets

A function update_style_set() could work similarly to ggplot2:::defaults(), but with the order of arguments reversed.

custom_styles <- style_set(
  setosa = style(color = colors["setosa"]),
  virginica = style(color = colors["virginica"]),
  versicolor = style(color = colors["versicolor"]),
)

iris_styles <- update_style_set(classic_style(), custom_styles)

I'm happy to put in some work to implement this. My suggestion is to start with option 3 and then use it to implement option 1. I'm less sure about option 2 and would leave that aside for now.

[teunbrand]

As a small aside: guide_marquee() works without having to define iris_styles. The rest seems like a good idea to me too.

[clauswilke]

Yes, I noticed today browsing the code that guide_marquee() apparently can do all sorts of things I'm not aware of. I need to read the documentation.