Docs: Field by Color tantalizing but ultimately disappointing. Maybe we need some documentation

[martingaleh]

Why is this needed:

I'm trying to color bars based on values in a category. There's this color by field option that ultimately does nothing

What would you like to be added:

Maybe better documentation or maybe its just a bug

Who is this feature for?

Humans

Here's some more detail:
If you see this:
https://user-images.githubusercontent.com/37156449/159819209-d7d40ce8-f5bb-41c1-8a6a-f5adf51d8320.png
and read this:
#46866
It almost seems like you can change the color of a bar by field. But ultimately I failed doing what I would think a reasonable person would do. Thus, maybe we need better documentation to highlight the various overrides or intricacies of configuration necessary for this to work like say excel or tableau where supplying the color is enough to have the colors change.
Here's a picture of other failed attempts to highlight this.

[leeoniya]

hmm, yeah i don't think this is currently possible, since the x axis labels are not "values". the values are the vertical heights of the bars. the same way that Value mappings will not work in TimeSeries if you want to use the timestamps (the x axis).

it might make sense to add support for this in BarChart. however, since each label is effectively a "group", this will only really make sense in the single-series case like the one shown.