Reorder fill and color scales to maximize perceptual contrast between adjacent segments

In stacked bar plots, ggplot2's default discrete palette assigns colors using level ordered (sometimes alphabetically), which often places perceptually similar colors next to each other. This function reassigns the same set of colors to factor levels so that visually adjacent segments receive maximally different colors. Both the fill and color scales are updated so that direct labels (e.g. from label_taxa = TRUE) stay in sync with the bars.

Usage

reorder_distinct_colors(
  p = NULL,
  alternate_lightness = FALSE,
  lightness_amount = 0.15,
  colorblind = FALSE
)

Arguments

p

A ggplot object that uses a discrete fill aesthetic. Can be omitted when using the + operator (e.g. p + reorder_distinct_colors()).

alternate_lightness

(logical, default FALSE) If TRUE, darken every other level to add a luminance alternation cue on top of hue differences.

lightness_amount

(numeric, default 0.15) Intensity of the lightness alternation (proportion to darken). Only used when alternate_lightness = TRUE.

colorblind

(logical, default FALSE) If TRUE, compute perceptual distances under simulated deuteranopia so that the reordering optimizes contrast for colorblind viewers.

Value

A new ggplot object with ggplot2::scale_fill_manual() and (if a color scale is present) ggplot2::scale_color_manual() replacing the original scales. When p is omitted, returns an object that can be added to a ggplot with +.

Author

Adrien Taudière

Examples

p <- tax_bar_pq(data_fungi_mini, taxa = "Class", fact = "Time")
reorder_distinct_colors(p)

reorder_distinct_colors(p, colorblind = TRUE)

p + reorder_distinct_colors(alternate_lightness = TRUE)


tax_bar_pq(data_fungi_mini, fact = "Height", taxa = "Order",
 nb_seq = FALSE, percent_bar = TRUE, label_taxa = TRUE,
 add_ribbon = TRUE, value_size=7, ribbon_alpha = .6,
 show_values=TRUE, label_size = 4, top_label_size = 8,
 minimum_value_to_show=0.05) |>
 reorder_distinct_colors(alternate_lightness=TRUE)