auto-generate a legend for Kyrix layers

[asah]

For high-dimensional data this gets esp interesting... think subway maps for NYC/London/Tokyo - they have an "example station" and then label it.

I doubt this is fully automatic, but then what's the right toolkit/API for making this easier for developers?

For example, if you turn on/off layers in a canvas how does the legend adjust itself?

[tracyhenry]

probably relevant: https://d3-legend.susielu.com/

[tracyhenry]

potentially useful: https://observablehq.com/@d3/color-legend