Returns exactly n colours. Priority order:
Details
Explicit
colorsargument - vector or palette name string.getOption("highdir.colors")- set viahd_set_theme().Built-in hdir rules:
n == 2 ->
"hdir2"two-colour teal/purple pairn <= 10 ->
"hdir"10-colour brand paletten > 10 -> viridis continuous scale
