Make individual colors from Vega color schemes accessible from Altair #2617
Comments
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@joelostblom I'm adding some context for what is going on in your script, and linking docs for Vega/Color Schemes The
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Yes, I agree that this is the better option |
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@joelostblom something that might help push this forward is an example that would benefit from more granular access to the color palettes. It could be an existing Maybe even adapting some of the code from @mattijn's work in doc/user_guide/color_usage.rst. |
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cc @hydrosquall regarding #2617 (comment) Wondering if you had any thoughts how we could expose the colors within a scheme from I feel like this would be simpler than vega/vega#1938 |
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I think vega/vega#1938 might not help with this issue, since Vega expressions do not have knowledge of color palettes. A naive Altair question as I haven't changed it before - do you have the ability to Altair's Python code ask Vega JS runtime for a response, so Vega can be an input to Python rather than just an output? If you can't do it at runtime, you could write a json file into Altair in a CI step. The schemes are queryable through the same API used to add new schemes, so you wouldn't have to do parsing of a JS file from a URL (though that approach is very ingenious). |
Clarification
Apologies @hydrosquall, the link I was drawing between these issues wasn't very clear (my bad). What they have in common is that resolving either could result in new So if that was the goal here, I think we'd be able to get there with less effort than (vega/vega#1938). Re
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Hi @dangotbanned , thanks very much for the clarifications and helpful links around expr evaluation and theme testing. I was thinking that when altair runs in jupyter it could communicate with Vega via the Jupyter widgets API (as we did in this streamlit POC ), but since altair can run without jupyter, this isn't a global solution. I think I see the connection you're drawing between the projects now - if there was a structured (JSON) representation of some Stepping from the code I'm curious about the end goal. If users are able to access the color definitions in python, what would they use it for? Would they be passed directly back into an One alternative devtool if they're not planning to use the colors right away would be to offer this info via a devtool page where you can
Alternately, we could augment the docs so clicking on a color block copies the hex code for that color to clipboard or displays in a tooltip, similar to how other color / design system sites work (e.g. material) |
Ah good find, it looks like those color scheme names originates in 
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Tasks
Description
I think it would be valuable to make all the individual colors from Vega schemes accessible programmatically from Altair. Since Vega stores them in a single file, we could parse that and create a Python dictionary that could be used to access single colors from each color scheme. Something like this:
Code block
{'blues': [ '#cfe1f2', '#bed8ec', '#a8cee5', '#8fc1de', '#74b2d7', '#5ba3cf', '#4592c6', '#3181bd', '#206fb2', '#125ca4', '#0a4a90'], 'greens': [ '#d3eecd', '#c0e6ba', '#abdda5', '#94d391', '#7bc77d', '#60ba6c', '#46ab5e', '#329a51', '#208943', '#0e7735', '#036429'] ...The text was updated successfully, but these errors were encountered: