"n sorted thresholds for n+1 bins" should read "n+1 sorted thresholds for n bins" ?

No, n thresholds produces n + 1 bins as written. The first and last bin are bounded by the domain.

I am finding that inset=0 sometimes leaves thin gaps.

Those gaps are antialiasing artifacts in most SVG implementations. You can avoid them either by setting a small negative inset so that the bars overlap, or by setting round: true on the scale so that the positions are rounded to the nearest pixel and drawn crisply.

You can also set shapeRendering: "crispEdges".

The last sentence can be updated since we have color legends now :)

true! thanks

I don't understand how to form the object for specifying separate thresholds for x and y. An example would be greatly appreciated.

for example: Plot.bin( {fill: "count"}, {x: {thresholds: 20, value: "weight"}, y: {thresholds: 5, value: "height"}} )

Thank you very much!