I think you all should get together and come up with a good implementation, and then petition Raymond Hettinger. Or maybe there is an existing open source 3rd party project that has code you can copy? I don’t recall if random has a C accelerator, but if it does, you should come up with C code as well.
—Guido On Mon, Jul 13, 2020 at 05:40 David Mertz <me...@gnosis.cx> wrote: > If we get this function (which I would like), the version with k items > (default 1) is much better. Some iterators cannot be repeated at all, so > not only is it slower to call multiple times if you need k>1, it's > impossible. > > On Mon, Jul 13, 2020, 8:37 AM David Mertz <me...@gnosis.cx> wrote: > >> This is an inefficient reservoir sampling. The optimized version does not >> need to call a random inclusion switch on every element, but can skip a >> geometrically ordered collection of (random) skip lengths to avoid most >> random inclusion decisions. >> >> Obviously, all items must be iterated over no matter what, but if >> randrange() is significant compared to the cost of next(), the >> skip-then-decide version is much preferred, especially as size grows. >> >> On Mon, Jul 13, 2020, 7:53 AM Oscar Benjamin <oscar.j.benja...@gmail.com> >> wrote: >> >>> I posted this in the thread about indexing dict items but it seems to >>> have been buried there so I'm starting a new thread. >>> >>> Maybe there could be a function in the random module for making a >>> random choice from an arbitrary (finite) iterable. This implementation >>> can choose a random element from an iterable by fully iterating over >>> it so is O(N) in terms of CPU operations but O(1) for memory usage: >> >> [,,,] > >>> -- --Guido (mobile)
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