Feature request: could the `scale_colour_gradientn` `values` argument allow the user to supply a function?

[davidhodge931]

It'd be cool if scale_colour_gradientn and scale_colour_stepsn values argument would accept a function like breaks does, as it would enable less hardcoding..

[teunbrand]

I'm not sure I understand how this would work. What would be the input to the values function? For context: the values argument is used immediately in scale construction, so it wouldn't have any access to anything that the scale can compute, since the scale hasn't been trained on the data yet.

[davidhodge931]

Oh ok, I'm not aware of how the underlying code works. If this is technically impossible, it can be closed. I just thought that this would be a super useful feature

[teunbrand]

Well it is technically challenging, I wouldn't say impossible. Is there a specific use-case that you have in mind for this that would be annoying to solve with the current options? I'm still not quite sure what should theoretically be used as input to the function.