Feature request: label_number() can prepend '≤' and '≥' symbols

[teunbrand]

When plotting a scale with squished oob-handling, I often find it clearer to indicate this with the ≤ and ≥ symbols prepended to the first and last labels respectively. Currently, this requires manually setting breaks and labels.

library(ggplot2)
library(scales)

ggplot(faithful, aes(waiting, eruptions)) +
  geom_point() +
  scale_y_continuous(
    limits = c(2, 4),
    breaks = c(2, 2.5, 3, 3.5, 4),
    labels = c("≤2.0", "2.5", "3.0", "3.5", "≥4.0"),
    oob = oob_squish
  )

^{Created on 2022-11-05 by the reprex package (v2.0.1)}

I think it would be great if this could be an option in the label_number() function, for example with a squished argument taking a logical vector for the lower and upper limit respectively.

ggplot(faithful, aes(waiting, eruptions)) +
  geom_point() +
  scale_y_continuous(
    limits = c(2, 4),
    labels = scales::label_number(squished = c(TRUE, TRUE)),
    oob = oob_squish
  )

[thomasp85]

I don't think this sort of special behaviour fits into scales. It is pretty easy to wrap label_number() in a function that prepends this to the output if you need it often

ggplot(faithful, aes(waiting, eruptions)) +
    geom_point() +
    scale_y_continuous(
        limits = c(2, 4),
        labels = \(...) {l <- scales::label_number()(...); l[c(1, length(l))] <- paste0(c("≤","≥"), l[c(1, length(l))]); l},
        oob = oob_squish
    )