On Sun, Aug 2, 2020 at 2:34 AM Christopher Barker <python...@gmail.com> wrote: > > On Sat, Aug 1, 2020 at 2:28 AM Marco Sulla <marco.sulla.pyt...@gmail.com> > wrote: >> >> On Sat, 1 Aug 2020 at 03:00, Inada Naoki <songofaca...@gmail.com> wrote: >>> >>> Please teach me if you know any algorithm which has no hole, O(1) >>> deletion, preserving insertion order, and efficient and fast as array. > > > I would think the goal here would be to re-order once in a while to remove > the holes. But that would take time, of course, so you wouldn't want to do it > on every deletion. But when? > > One option: maybe too specialized, but it could re-pack the array when an > indexing operation is made -- since that operation is O(N) anyway. And that > would then address the issue of performance for multiple indexing operations > -- if you made a bunch of indexing operation in a row without deleting (which > would be the case, if this is an alternative to making a copy in a Sequence > first), then the first one would repack the internal array (presumably faster > than making a copy) and the rest would have O(1) access. >
Repacking is mutation, and mutating dict while iterating it breaks the iterator. But `d.items()[42]` don't looks like mutation. > Given that this use case doesn't appear to be very important, I doubt it's > worth it, but it seems it would be possible. > > Another thought -- could the re-packing happen whenever the entire dict is > iterated through? Though maybe there's no way to know when that's going to > happen -- all you get are the individual calls for the next one, yes? > You are right. it couldn't. -- Inada Naoki <songofaca...@gmail.com> _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/ED2GRWD4RARR2LGP45PK4M6R3MLTAF75/ Code of Conduct: http://python.org/psf/codeofconduct/
