More configurable continuous colorscale defaults

[cpsievert]

scale_[fill/colour]_[continuous/binned] have a type argument which provides an entrypoint for customizing the scale's default. Currently, type only supports gradient and viridis. It seems reasonable that it could also support an arbitrary function, which would make the default much more configurable. For example:

library(ggplot2)
scale_colour_custom <- function(...) {
  scale_colour_gradient(..., low = "white", high = "green")
}
options(ggplot2.continuous.colour = scale_colour_custom)
qplot(1:10, 1:10, color = 1:10)

[cpsievert]

Done in #3828

[fcecinati]

The issue has been closed, but the example above is still not working with the provided syntax in my session (R4.0 ggplot2 3.3.1), returning the followign error:

> library(ggplot2)
> scale_colour_custom <- function(...) {
+   scale_colour_gradient(..., low = "white", high = "green")
+ }
> options(ggplot2.continuous.colour = scale_colour_custom)
> qplot(1:10, 1:10, color = 1:10)
Error in switch(type, gradient = scale_colour_gradient(...), viridis = scale_colour_viridis_c(...),  : 
  EXPR must be a length 1 vector

If a different syntax is needed, could you please provide an example?

Screenshot of my sessionInfo()