(50g) Removing Objects From Lists Quickly

[John Keith]

(01-09-2019 06:29 PM)DavidM Wrote:  Difference may need some clarification, though. Am I correct in assuming that the target here is what is described on this page as the "relative complement"? That would imply that order of arguments is important (ie. "difference" is not commutative).

There is definitely some confusing terminology in this area. "difference" as implemented by GoferLists as Diff and my difference program, is what Wikipedia refers to as "relative complement". Called Complement in Mathematica. Confusingly, the Prime's DIFFERENCE command implements symmetric difference, not complement.

You are correct that set difference aka complement is non-commutative.