A scale is a function from a domain (data values) to a range (pixels, radii or colors). It replaces Keyed Joins's hand-tuned constants, picks round tick values and runs backward with invert(); an axis draws its ticks as SVG.
A scale is a function from a domain (data values) to a range (pixels, radii or colors). It replaces Keyed Joins's hand-tuned constants, picks round tick values and runs backward with invert(); an axis draws its ticks as SVG.