A better “label centroid” initializer? (polylabel)

The centroid of a geometry is sometimes outside of it, for example (but not exclusively) with a MultiPolygon such as France+Guyane. This can result in labels or interactive tips that are quite far off from the shape they identify.

A great solution is to use @mapbox/polylabel, which guarantees that the center is inside —and furthermore at an optimal position for a centered label. The dependency is less that 1kB over the wire, including tinyqueue. An alternative approach could be to add an option to Plot.centroid, to make it choose the centroid of the largest polygon when given a multipolygon. Subpar solution, but cheaper.

Prototype https://observablehq.com/@observablehq/plot-pole-of-inaccessibility-1587

Start at the Plot.centroid entry point and inspect the linked Observable prototype for the proposed pole-of-inaccessibility approach. Compare the @mapbox/polylabel dependency with the largest-polygon alternative, then confirm the chosen behavior keeps labels or interactive tips within the geometry.