Plot.groupX({filter: () => true})

[Fil]

follow-up on #499: using Plot.groupX({filter: () => true}…) creates empty points where there is no data

todo:

• the code is a bit ugly
• for feature parity with binX, the filter should receive the data, not just the index; and maybe the group too?
• use InternSet
• motivate with a meaningful example
• use filter: "all" as a shorthand for {filter: () => true}?
• optimize: we can probably sort once instead of sorting each group
• optimize: probably no need to loop through X × Y if there is no filter
• can probably do without sorting (ref. sort groups #414)

[mbostock]

Yeah, nice, this is what I was imagining with the Cartesian product idea. Not sure how urgently we should tackle this but I like the direction. 🙂

[Fil]

obsolete since v0.2!