How to mix optimally a color palette (n=5) with a second color palette (n=4) plus a luminance variable (n=4) in a matrix (total 5*4*4=80 colors)

Question

Using R, would there be a way, whatever it is, to mix a red palette (n=5 levels) with an orange palette (n=4 levels), and to mix each the 5x4 resulting colors according to a luminance (or transparency/opacity) variable (n=4 levels) so that the 5x4x4=80 colors are optimally distinct from each other (i.e., evenly distributed), and then get the corresponding colors hexadecimal codes?

Below, an excel overview of the colors/luminance matrix to mix.

Thanks a lot

Answer 1

I did not find an appropriate way/function to mix evenly the red and orange palettes. Hence I looked for the best mixes, one by one, thanks to the excellent website trycolors.com/custom). Then, I adjusted the 4 contrast levels using the swatchplot function (darken option) from the colorspace package, as follows:

# select your gradient colors (hexadecimal codes) and optimize them: https://trycolors.com/custom/
library(colorspace)
# better visualization for comparison of color shades with this layout:
a0_hex <- c(
  "#ffffdd","#fdf3be","#ffea90","#fbdb7a",
  "#f9ceca","#fdc2ae","#ffa98a","#f99662",
  "#fb9991","#f58473","#ef6e44","#e56223",
  "#f15854","#ef3418","#dd3818","#cc3a01",
  "#d70303","#ca0303","#ba0808","#a60505")

# darken (or lighten) colors: https://colorspace.r-forge.r-project.org/reference/lighten.html
a1_dark <-
  swatchplot(
    "  0%" = a0_hex,
    " 10%" =  darken(a0_hex, 0.1),
    " 20%" =  darken(a0_hex, 0.2),
    " 30%" =  darken(a0_hex, 0.3),
    nrow = 4, off = c(0, 0))

a2_dark <- as.data.frame(a1_dark)
a2_dark

# rearrange the order of colors as required
library(tidyr)  # From long to wide table: https://mgimond.github.io/ES218/Week03b.html
a3_red_0 <- a2_dark %>% select(1:4) %>% pivot_longer(cols=1:4, names_to = "col", values_to = "hex")
a3_red_1 <- a2_dark %>% select(5:8) %>% pivot_longer(cols=1:4, names_to = "col", values_to = "hex")
a3_red_2 <- a2_dark %>% select(9:12) %>% pivot_longer(cols=1:4, names_to = "col", values_to = "hex")
a3_red_3 <- a2_dark %>% select(13:16) %>% pivot_longer(cols=1:4, names_to = "col", values_to = "hex")
a3_red_4 <- a2_dark %>% select(17:20) %>% pivot_longer(cols=1:4, names_to = "col", values_to = "hex")

# join and get all hex codes in one single column
a3_red_all <- rbind(a3_red_0, a3_red_1, a3_red_2, a3_red_3, a3_red_4) %>% select(!col)

# show the 5x4x4 = 80 colors
windows(200, 1800, pointsize = 12, xpos = 650, ypos = 25)
swatchplot(a3_red_all, nrow = 80, off = c(0, 0))