Theme shortcuts: subtheme

Mix.install([
  {:giggly, path: Path.join(__DIR__, "..")},
  {:kino, "~> 0.19"}
  ])

alias Giggly.Plot

mtcars = Giggly.Datasets.mtcars()

render = fn plot ->
  plot
  |> Giggly.to_svg()
  |> IO.iodata_to_binary()
  |> Kino.Image.new(:svg)
end

About this notebook

This notebook follows the examples on ggplot2's reference page for theme_sub_axis(), which covers theme_sub_axis_x(), theme_sub_axis_y(), theme_sub_axis_bottom(), theme_sub_axis_top(), theme_sub_axis_left(), theme_sub_axis_right(), theme_sub_legend(), theme_sub_panel(), theme_sub_plot() and theme_sub_strip() too, in the order the page gives them. Each example shows ggplot2's code first and then Giggly's. An example Giggly cannot draw yet keeps its ggplot2 code and names what it is waiting for, so the page is also a list of what remains.

These functions are shortcuts for theme() with shorter argument names: each sets the elements of one part of the plot, so theme_sub_axis_bottom(title = ...) sets what theme(axis.title.x.bottom = ...) sets. There is one for all the axes, for both x axes, for both y axes and for each of the four, and one each for the legend, the panels, the whole plot and the facet strips. Giggly sets the same elements with Giggly.Plot.theme/2, but has none of these functions (theme_sub_axis_bottom()). A plot is described with Giggly.Plot and drawn with Giggly.to_svg/2, which returns an SVG document. The setup cell aliases Giggly.Plot, so the cells write Plot.new/2, and defines render, which draws a plot and shows it below the cell with Kino.Image. The data is Giggly.Datasets.mtcars/0, R's mtcars: 32 cars from the 1974 Motor Trend US magazine, which the setup cell binds to mtcars, R's name for it.

Styling the bottom axis with theme()

# A standard plot
p <- ggplot(mtcars, aes(disp, mpg, colour = drat)) +
  geom_point()

red_text <- element_text(colour = "red")
red_line <- element_line(colour = "red")

# The theme settings below:
p + theme(
  axis.title.x.bottom = red_text,
  axis.text.x.bottom  = red_text,
  axis.line.x.bottom  = red_line,
  axis.ticks.x.bottom = red_line
)

An element is a keyword list of its properties, so red_text and red_line are keyword lists.

p =
  mtcars
  |> Plot.new(%{x: :disp, y: :mpg, colour: :drat})
  |> Plot.geom_point()

red_text = [colour: "red"]
red_line = [colour: "red"]

p
|> Plot.theme(
  axis_title_x_bottom: red_text,
  axis_text_x_bottom: red_text,
  axis_line_x_bottom: red_line,
  axis_ticks_x_bottom: red_line
)
|> render.()

The same with theme_sub_axis_bottom()

# Are equivalent to these less verbose theme settings
p + theme_sub_axis_bottom(
  title = red_text,
  text  = red_text,
  line  = red_line,
  ticks = red_line
)

Not in Giggly yet: theme_sub_axis_bottom().