On Mon, Nov 6, 2017 at 4:28 PM, Stephan Hoyer <sho...@gmail.com> wrote:
> >> What's needed, though, is not just a single ABC. Some thought and design >> needs to go into segmenting the ndarray API to declare certain behaviors, >> just like was done for collections: >> >> https://docs.python.org/3/library/collections.abc.html >> >> You don't just have a single ABC declaring a collection, but rather "I am >> a mapping" or "I am a mutable sequence". It's more of a pain for developers >> to properly specify things, but this is not a bad thing to actually give >> code some thought. >> > > I agree, it would be nice to nail down a hierarchy of duck-arrays, if > possible. Although, there are quite a few options, so I don't know how > doable this is. > Exactly -- there are an exponential amount of options... > Well, to get the ball rolling a bit, the key thing that matplotlib needs > to know is if `shape`, `reshape`, 'size', broadcasting, and logical > indexing is respected. So, I see three possible abc's here: one for > attribute access (things like `shape` and `size`) and another for shape > manipulations (broadcasting and reshape, and assignment to .shape). I think we're going to get into an string of ABCs: ArrayLikeForMPL_ABC etc, etc..... > And then a third abc for indexing support, although, I am not sure how > that could get implemented... This is the really tricky one -- all ABCs really check is the existence of methods -- making sure they behave the same way is up to the developer of the ducktype. which is K, but will require discipline. But indexing, specifically fancy indexing, is another matter -- I'm not sure if there even a way with an ABC to check for what types of indexing are support, but we'd still have the problem with whether the semantics are the same! For example, I work with netcdf variable objects, which are partly duck-typed as ndarrays, but I think n-dimensional fancy indexing works differently... how in the world do you detect that with an ABC??? For the shapes and reshaping, I wrote an ShapedLikeNDArray mixin/ABC > for astropy, which may be a useful starting point as it also provides > a way to implement the methods ndarray uses to reshape and get > elements: see > https://github.com/astropy/astropy/blob/master/astropy/utils/misc.py#L863 Sounds like a good starting point for discussion. -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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