A pointy-top hex lattice in data units: points are assigned to the
nearest centre via cube rounding, so bins are fixed by (w, h, origin)
alone — unlike floor-binned rectangles, they don’t move when the data
extent changes.
Hexagonal binning on a fixed hex lattice (data units), unlike the
floor-binned staggered rectangles this replaces (see the 0.20.0
CHANGELOG). Output: x, y (hex centres), count, density, ncount,
ndensity, width, height, fill (= count, back-compat), n
(unweighted point count), q, r.