viridis type for discrete scales ?

[Ahobert]

I noticed that scale_colour/fill_continuous has a type option specifying wheter to use gradient or viridis palettes. in order to enable color blindness friendly visualisation. Is there any particular reason why the same option is not (yet) implemented in scale_colour/fill_discrete or scale_colour/fill_hue, respectively?

[karawoo]

I think the main reason is that we changed the default behavior for continuous color scales to use viridis, but also kept the ability to use the previous default (gradient). For discrete scales, viridis is less often a good choice unless the number of categories is very small. But you can still use it with discrete data using scale_colour_viridis_d()/scale_fill_viridis_d().

[teunbrand]

I think this inconsistency falls under the umbrella of #2851, so I'll close this here in favour of that issue.