feat: Adds 4 missing carbon themes, provide autocomplete

[dangotbanned]

Related

• feat: add all 4 carbon themes vega-themes#587
• feat(python!): Use Altair in DataFrame.plot pola-rs/polars#17995 (comment)

Examples

• https://vega.github.io/vega-themes/?theme=carbonwhite
• https://vega.github.io/vega-themes/?theme=carbong10
• https://vega.github.io/vega-themes/?theme=carbong90
• https://vega.github.io/vega-themes/?theme=carbong100

Bonus

Support autocomplete for themes.enable(name).

[binste]

Thanks! And great to have autocomplete on this :) Added one suggestion

[binste]

Instead of defining the theme names twice, I think you could specify _ThemeName as you've done here and then VEGA_THEMES could become typing.get_args(_ThemeName). See https://docs.python.org/3/library/typing.html#typing.get_args

[dangotbanned]

Thanks @binste for the review!

I think I could rework this to use typing.get_args, but wanted to note some things first that led to my duplication here.

---

I'm viewing _ThemeName as a short-term solution:

• Explicitly marking it "private"
• Defining within a TYPE_CHECKING block to prevent it existing at runtime.

I don't think I've used this pattern anywhere in altair before, but some examples in other projects (for their own reasons):

Examples

• https://github.com/pytest-dev/pytest/blob/dc756f4117f7cbabbe0866bab1fe562ac287cc03/src/_pytest/mark/structures.py#L428-L482
• https://github.com/pytest-dev/pytest/blob/dc756f4117f7cbabbe0866bab1fe562ac287cc03/src/_pytest/mark/structures.py#L501-508
• https://github.com/narwhals-dev/narwhals/blob/6fcc6a6ab3b3a5831db14d0e7e18fc45c43a0594/narwhals/schema.py#L13-L19
• https://github.com/narwhals-dev/narwhals/blob/6fcc6a6ab3b3a5831db14d0e7e18fc45c43a0594/narwhals/typing.py#L9-L32

IIRC, I'd need to move _ThemeName out of that block or use typing.get_type_hints

I'd also need to remove "default", "opaque" in the def of _ThemeName or later during iteration:

Registration source

altair/altair/vegalite/v5/theme.py

Lines 45 to 61 in c12ca27

	themes.register(
	"default",
	lambda: {"config": {"view": {"continuousWidth": 300, "continuousHeight": 300}}},
	)
	themes.register(
	"opaque",
	lambda: {
	"config": {
	"background": "white",
	"view": {"continuousWidth": 300, "continuousHeight": 300},
	}
	},
	)
	themes.register("none", dict)
	for theme in VEGA_THEMES:
	themes.register(theme, VegaTheme(theme))

---

For a long-term solution, I'd want to:

• Extract the names directly from source as (VegaThemes: Literal[...])
• Define altair themes as (AltairThemes: Literal["opaque", ...)
  • Your comment which was what sparked this PR 😄
  • changing-the-theme which states a plan to add more in the future
• _ThemeName -> DefaultThemes: TypeAlias = AltairThemes | VegaThemes
• Annotate themes.enable(name: DefaultThemes)
• Revisit the need for defining this across two theme.py modules, as part of Flatten the package structure #3337

---

Essentially I want to keep this as flexible as possible for now.

Planning to open another issue to discuss themes more generally.
There are other ideas I've had and I got the impression you might also have some of your own 🤝

[binste]

Steps re long-term solution sound great! We could probably keep it simple and just fetch the themes from the latest source file in vega-themes which you linked. Or the file which was part of the latest release.

Let's continue the discussion in a new issue as you suggested, thanks for bringing it up! :) I have some notes on providing a better default theme and additional documentation around customization (advanced legend manipulation, vertical y-axis titles, y-axis on the right side with tick labels on top of the ticks, ...)

[binste]

I've added 2 comments to mention that these two variables need to be kept in sync for now. Just in case we don't get to an improved solution for a while.

[dangotbanned]

Steps re long-term solution sound great! We could probably keep it simple and just fetch the themes from the latest source file in vega-themes which you linked. Or the file which was part of the latest release.

Let's continue the discussion in a new issue as you suggested, thanks for bringing it up! :) I have some notes on providing a better default theme and additional documentation around customization (advanced legend manipulation, vertical y-axis titles, y-axis on the right side with tick labels on top of the ticks, ...)

Perfect, thanks again @binste