HDA-branded continuous fill scale

A sequential or diverging colorspace HCL ramp, tuned and CVD-checked against protanopia, deuteranopia, and tritanopia in the Ramp Lab review (plans/ramp-lab/REVIEW.md).

Usage

scale_fill_hda_c(
  palette = c("sequential", "diverging"),
  direction = 1,
  na.value = .brands$hda$na_color,
  guide = "colorbar",
  ...
)

Arguments

palette

One of "sequential" (default) or "diverging"

direction

For palette = "sequential", 1 (default) maps higher values to darker colors; -1 reverses so higher values are lighter. For palette = "diverging", 1 (default) maps low values toward the first arm and high values toward the second, as constructed in the Ramp Lab review; -1 swaps which arm represents low vs. high.

na.value

Default color for NA values (#cfcfd0, HDA Light Gray)

guide

Legend representation for scale

...

Other arguments passed on to ggplot2::continuous_scale()

Value

A ggplot2::continuous_scale() object.

Diverging palette usage

7-class diverging maps built from these ramps lose sign distinction in their innermost class pair under protanopia (structural to the shared cream center) — always pair a palette = "diverging" map with a legend or direct labels. See plans/DECISIONS.md (2026-07-18).

HDA diverging is provisional

HDA's diverging ramp (Blue vs Coral) is a near-twin of PHA's (Dark Blue vs Red) and is pending a follow-up Ramp Lab pass to differentiate it before final adoption (see plans/DECISIONS.md, 2026-07-18). It ships now so the scale matrix is complete; treat it as subject to change.

Examples

library(ggplot2)
ggplot(mtcars, aes(wt, mpg, fill = disp)) +
  geom_point(shape = 21) +
  scale_fill_hda_c()