feat: Adds vega-themes.json using vl_convert

[dangotbanned]

#3519 (comment)

Provides inline definitions from vega-themes.

Thought this made more sense as .json, rather than a dict within a module.

Eventually these could each be read into a Theme/Config TypedDict as mentioned in #3519

[dangotbanned]

@jonmmease Seem to have resolved in 4c3b189 (#3523) by pruning my envs.

I don't quite understand how my vl_convert version wouldn't have included the newer themes #3523 (comment), but all good now

[dangotbanned]

@jonmmease we could keep this PR atomic and just merge as-is.

I did some playing around with alt.Config yesterday, but I think it might be some time before I've got a clean solution to recursively build a TypedDict and (str|float|list) equivalent hierarchy.

What do you think?

[jonmmease]

Yeah, it's not a very large file, so I think it's fine to merge without being used. And I think someone could technically load the json file directly using importlib.resources if they really wanted to.

Let's leave it open another day to see if there are any other opinions. Feel free to ping me in 24 hrs if we haven't heard anything and I'll merge it.

[dangotbanned]

Sounds good to me @jonmmease

And I think someone could technically load the json file directly using importlib.resources if they really wanted to.

This was the shortest I came up with:

diff --git a/altair/vegalite/v5/theme.py b/altair/vegalite/v5/theme.py
index a3c62165..097e7b30 100644
--- a/altair/vegalite/v5/theme.py
+++ b/altair/vegalite/v5/theme.py
@@ -53,6 +53,15 @@ VEGA_THEMES = [
 ]
 
 
+def _load_themes():
+    import json
+    from pathlib import Path
+
+    from altair.vegalite.v5 import schema
+
+    return json.loads((Path(*schema.__path__) / "vega-themes.json").read_text())
+
+
 class VegaTheme:
     """Implementation of a builtin vega theme."""
 

I'd prefer leaving it out for now, since there is quite a lot of variation between the themes.
Navigating them in an ipython environment is fine, but statically this alone isn't much help IMO

[jonmmease]

Sorry I wasn't very clear there. I wasn't suggesting we provide a function to do this. Just pointing our that an end-user could do this if they needed to for some reason.

[dangotbanned]

FYI @binste this combines both of our comments #3516 (comment)

[dangotbanned]

Let's leave it open another day to see if there are any other opinions. Feel free to ping me in 24 hrs if we haven't heard anything and I'll merge it.

@jonmmease if you're available to merge

[binste]

LGMT! Agree that with 24kb it's small enough to include directly. Merging as Jon has indicated that he's ok with it as well.