Provide hooks for ggplot2 gradient and discrete scales

[coatless]

Think about adding some hooks for ggplot2... (Package will have more dependencies though... )

[brianwdavis]

I'm writing a package that implements a particular discrete mapping of continuous color maps. In order to provide support for cetcolor I wrote a thin wrapper:

cet_discrete_pal <- function(...) {
  function(n) {
    cet_pal(n, ...)
  }
}

This returns a function that only takes argument n and returns a vector of colors. That way cet_discrete_pal behaves just like hue_pal, brewer_pal, and viridis_pal.

You can use it like so:

scale_color_cet <- function(guide = "legend", ...) {
  discrete_scale("colour", "cet", guide = guide, palette = cet_discrete_pal(...))
}

And then in use:

ggplot(diamonds, aes(clarity, price, color = clarity)) + 
  geom_boxplot() +
  scale_color_cet(name = "bgy")

Feel free to run with it, but it would be nice if cet_discrete_pal (or similarly named) would be in a future release, so it could be called in the same way using the discrete_scale API.

[coatless]

@brianwdavis thanks. To keep dependencies low, I may write a second package that hooks into cetcolor with the aforementioned ggplot2 support.

[coatless]

@brianwdavis, I forgot to ask, when do you need this by?

[brianwdavis]

I've not really got any timeframe. I will probably just include the cet_discrete_pal() and deprecate it later if you implement something similar.