Support ephemeral themes via `plt(..., theme = ...)`?

[grantmcdermott]

Currently, we require that users (un)set themes globally and in persistent fashion via

tinytheme("<theme>")

But there are also cases where it would be useful to set ephemeral themes that don't persist. (An example: For a package that calls tinyplot as a dependency, where they would like a particular styling for their plots, but not have to override the user's global settings.)

Perhaps we should enable this via an additional argument in the main function:

tinyplot(..., theme = "<theme>")

?

[zeileis]

That's a good idea, I like it. For modified themes, i.e., tinytheme("<theme>", ...) where ... contains further settings, one could use the syntax:

tinyplot(..., theme = list("<theme>", ...))

and then internally:

if (is.character(theme) && length(theme) == 1L) {
  tinytheme(theme)
} else if (is.list(theme)) {
  do.call("tinytheme", theme)
} else {
  stop("'theme' should either be a single character or a list")
}

I'm just wondering whether tpar() is sufficient to query the current setting and then restore it. For example in:

tinytheme("<theme1>", ...)
tinyplot(..., theme = "<theme2>")

we would first have to query the current setting inside tinyplot() and then restore it at the end. Is tpar() sufficient for that? I'm specifically thinking about the hooks which are used inside tinytheme(). But I haven't tried it out myself, yet.

[zeileis]

Playing around with this a bit, I came across an issue that might be related but maybe it needs to go into a separate issue. I tried:

tinyplot(dist ~ speed, data = cars)

tinytheme("clean2", pch = 17, cex = 3)
tinyplot(dist ~ speed, data = cars)

tinytheme()
tinyplot(dist ~ speed, data = cars)

First, I was surprised that cex = 3 appears to be expanded to various elements (main, axis, x/ylab) which isn't obvious to me from the documentation.

Second, and probably more importantly, I was surprised that reverting to the default theme does not unset this. Shouldn't the third panel look like the first panel?

[grantmcdermott]

Yep, that's definitely not the desired or expected behaviour. Thanks for flagging.