Show counts in coloring legend

[corneliusroemer]

Context

Sometimes I apply colorings to get an idea of how common various category options are. Examples:

• I add genotypes to see which genotypes are how common, when looking at the SARS-CoV-2 reference tree to see if something is a common combination of mutations
• I select country coloring when pango designating, to see which countries are most common for a particular subtree I'm currently looking at

In those circumstances I actually don't really care so much about where on the tree the dots fall, more about how often they appear. I.e. what I really want is a quick frequency table for the current selection of tips.

It would be amazing if this could be (optionally) be offered somehow. I was just thinking it might be displayed next to the colorings legend. This might be super ugly and there might be better ways of doing this. But given how much white space we have, it might be something fun to play with.

Consider this (actual) use case that made me realize this would be a cool feature (the feature would be the red text)

This might be a bit too much for some people but I could see it as a power user feature that should not be too hard to implement and enrich Auspice further.

[joverlee521]

Oh interesting idea! I wonder if this is something we could support via the scatterplot view.

This is displaying the node ordering on the y-axis, but maybe we could add node count?

[jameshadfield]

From #1974,

hovering over the legend swatch [of a continuous trait] highlights the tips whose values fall into the corresponding bin, but we don't actually convey the range of the bin but we probably should (e.g. via a small pop-up over the legend)

I wonder if adding on-hover boxes for the legend more generally would be useful, and one of the things they can convey is the counts of each value?