On Tue, Jul 3, 2018 at 8:24 AM, Steven D'Aprano <st...@pearwood.info> wrote:
> On Tue, Jul 03, 2018 at 09:23:07AM -0400, David Mertz wrote: > > > My problem with the second idea is that *I* find it very wrong to have > > something in itertools that does not return an iterator. It wrecks the > > combinatorial algebra of the module. > hmm -- that seems to be a pretty pedantic approach -- practicality beats purity, after all :-) I think we should first decide if a grouping() function is a useful addition to the standard library (after all: "not every two line function needs to in the stdlib"), and f so, then we can find a home for it. personally, I'm wondering if a "dicttools" or something module would make sense -- I imagine there are all sorts of other handy utilities for working with dicts that could go there. (though, yeah, we'd want to actually have a handful of these before creating a new module :-) ) > That said, it's easy to fix... and I believe independently useful. Just > > make grouping() a generator function rather than a plain function. This > > lets us get an incremental grouping of an iterable. > > We already have something which lazily groups an iterable, returning > groups as they are seen: groupby. > > What makes grouping() different from groupby() is that it accumulates > ALL of the subgroups rather than just consecutive subgroupings. well, yeah, but it wont actually get you those until you exhaust the iterator -- so while it's different than itertools.groupby, it is different than itertools.groupby(sorted(iterable))? In short, this wouldn't really solve the problems that itertools.groupby has for this sort of task -- so what's the point? > As for where it belongs, perhaps the collections module is the least worst fit. That depends some on whether we go with a simple function, in which case collections is a pretty bad fit (but maybe still the least worse). Personally I still like the idea of having this be special type of dict, rather than "just a function" -- and then it's really obvious where to put it :-) -CHB -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception chris.bar...@noaa.gov
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