`guide_axis_nested()` : `pad_discrete=0`

[DanChaltiel]

Hi,

Thank you for this incredible package.

I'm building a rather large plot with a nested categorical x-axis.
My X labels are long and tend to overwrite each other, so I want to add a 30°angle on the top level.
However, this caused several alignment problems I couldn't solve using the available documentation.

library(tidyverse)
library(legendry)

p = mpg |>
  filter(class %in% c("compact", "minivan")) |>
  mutate(cyl = str_replace(cyl, "4", "four"),
         cyl = str_replace(cyl, "5", "five"),
         cyl = str_replace(cyl, "6", "six"),
         cyl = str_replace(cyl, "8", "eight")) |>
  ggplot() +
  aes(interaction(cyl, class), hwy) +
  geom_boxplot() +
  labs(x=NULL)

Default behaviour (for comparison)

This is very nice!

p +
  guides(
    x = legendry::guide_axis_nested()
  )

Angle on top level

With an angle on the top level, the alignment is OK, but the brackets shrink due to pad_discrete=0.
Unfortunately, removing it causes the alignment to be very bad.

levels_text = list(element_text(angle = 30, hjust = 1, vjust = 1), 
                   element_text(angle = 0, hjust = 0.5, vjust = 1))
p +
  guides(
    x = legendry::guide_axis_nested(levels_text=levels_text, pad_discrete=0)
  )

Is there a way to get the best of the two worlds?

My first guess would be to state pad_discrete=c(0, NA) to have 0 for the top level and waiver() for the bottom level.

PS: I couldn't get reprex to work with legendry, I get crashes every times.

[teunbrand]

Hi Dan,

There is a way to get this roughly to how you describe it.
First, we use a fixed angle for the bottom text (0) so it stays horizontal.
Then we use the guide's angle argument to simultaneously control the text angle and its justification.
There will be no need to tweak pad_discrete in this case.

library(tidyverse)
library(legendry)

p = mpg |>
  filter(class %in% c("compact", "minivan")) |>
  mutate(cyl = str_replace(cyl, "4", "four"),
         cyl = str_replace(cyl, "5", "five"),
         cyl = str_replace(cyl, "6", "six"),
         cyl = str_replace(cyl, "8", "eight")) |>
  ggplot() +
  aes(interaction(cyl, class), hwy) +
  geom_boxplot() +
  labs(x=NULL)

# Here NULL will substitute default text
levels_text = list(NULL, element_text(angle = 0))

p +
  guides(
    x = legendry::guide_axis_nested(levels_text = levels_text, angle = 30)
  )

^{Created on 2025-03-31 with reprex v2.1.1}

EDIT:
To also get the 'compact'/'minivan' labels correct, you can use element_text(angle = 0, hjust = 0.5).