Color Palettes in stemtool

stemtool provides a set of color palettes for plotting. There are three types of palettes:

• Diverging - used for variables where low values are the opposite of high values. Typically likert items, where low values signify agreement and high values signify disagreement.

  • Available diverging palettes: modern, gruvbox_div.

• Nominal - used for variables where categories have no set order. Typically gender, countries of origin or occupation.

  • Available nominal palettes: gruvbox.

• Sequential - used for variables where higher values indicate higher frequency/concentration of something. Typically level of unemployment, number of people with tertiary education or socioeconomic class.

  • Available sequential palettes: none (for now).

Accesing stemtool palettes

Color codes from palettes can accessed using stem_palettes() function. The function expects palette name (see above) and optionally the number of colors to extract. By default, all colors are extracted. Palettes can be visually inspected with show_col() function from scales package:

stem_palettes(palette = "modern", n = 5)
#> [1] "#35978F" "#80CDC1" "#B0C89F" "#DFC27D" "#BF812D"
show_col(stem_palettes(palette = "modern"))

Using palettes in ggplot2

Palettes can be used in ggplot2 figures by using functions scale_color_stem() and scale_fill_stem(). Specific palette can be chosen by palette argument, using direction = -1 can be used to reverse the order of colors. Note that for diverging palettes, colors are used from both ends of the palette in an alternating pattern.

mtcars |> 
  within(gear <- as.factor(gear)) |> 
  ggplot(aes(x = mpg,
             y = hp,
             color = gear)) +
  geom_point(size = 3) +
  scale_color_stem(palette = "modern")