Symmetric difference for Set and IntSet
Hi all, I propose to add a new combining function to `Data.Set` and `Data.IntSet` with the following semantics (but better implementation): symmetricDifference :: Set a -> Set a -> Set a symmetricDifference x y = (x \\ y) <> (y \\ x) The context is that Federico (CC'ed) is working on a GSoC project about faster factorisation algorithms in `arithmoi` (http://hackage.haskell.org/package/arithmoi), and the symmetric difference is a basic building block for sparse linear algebra over GF(2) field. Best regards, Andrew
+1
Symmetric difference has previously briefly come up on the containers
issue tracker: https://github.com/haskell/containers/issues/162#issuecomment-222337552
David mentions the idea of a generalized merge API similarly to the
one for Map and IntMap there, which would be nice to have now. Not a
prerequisite for the addition though IMHO.
Am Mi., 17. Juni 2020 um 21:25 Uhr schrieb Andrew Lelechenko
Hi all,
I propose to add a new combining function to `Data.Set` and `Data.IntSet` with the following semantics (but better implementation):
symmetricDifference :: Set a -> Set a -> Set a symmetricDifference x y = (x \\ y) <> (y \\ x)
The context is that Federico (CC'ed) is working on a GSoC project about faster factorisation algorithms in `arithmoi` (http://hackage.haskell.org/package/arithmoi), and the symmetric difference is a basic building block for sparse linear algebra over GF(2) field.
Best regards, Andrew _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
On 17/06/2020 21.25, Andrew Lelechenko wrote:
Hi all,
I propose to add a new combining function to `Data.Set` and `Data.IntSet` with the following semantics (but better implementation):
symmetricDifference :: Set a -> Set a -> Set a symmetricDifference x y = (x \\ y) <> (y \\ x)
The context is that Federico (CC'ed) is working on a GSoC project about faster factorisation algorithms in `arithmoi` (http://hackage.haskell.org/package/arithmoi), and the symmetric difference is a basic building block for sparse linear algebra over GF(2) field.
+½. I think it's probably going to be useful, but I would suggest an algorithm which actually returns each of the terms here (as a tuple), i.e. The "added" bits The "removed" bits The "common" bits This may not be *that* useful for sets per se, but I've lost count of how often I've had to implement a similar thing for maps.
participants (3)
-
Andrew Lelechenko -
Bardur Arantsson -
Simon Jakobi