On Wed, Nov 30, 2022 at 10:39 AM Sebastian Berg <sebast...@sipsolutions.net> wrote: > > Hi all, > > there is a discussion about how `round(array)` should behave in: > > https://github.com/numpy/numpy/issues/6248 > > There is some discussion about object arrays which should probably be > fixed for `around()` in that ago. > > Otherwise, the is the question what to do about the fact that: > > * round(np.float64(2.**64)) -> 18446744073709551616 (a Python int) > * round(np.array([2., 3., 2.**64]) can only return float or integer > > The NumPy `np.round`/`np.around` (same function) functions always > return the same dtype. > > We can either ignore that discrepancy, or opt to raise an error, so > that: > > >>> round(np.array([2., 3.5])) > TypeError: Rounding a NumPy float array cannot return integers, > use `round(arr, ndigits=0)` or `round(arr, 0) to indicate that a > float result is desired. > > In the call today, I think we leaned a bit towards ignoring it, but if > I read Aaron correctly, he prefers the error and it may be the > conservative choice.
I guess I weakly prefer it, but I mostly just suggested it because it is the conservative option. Making ndigits=None just match ndigits=0 (so that round() works like around()) is also fine IMO. I don't think it would be too surprising for most people to have round() work that way on arrays. What I feel more strongly about is that there shouldn't be distinct behavior for scalars vs. arrays, and the output dtype shouldn't be value-based. Aaron Meurer > > We could of course do other things (i.e. return an integer `intp` > array) but that would probably require a hard error for overflows > (which is different from `np.rint(arr).astype(np.intp)`. > > Are there any small or big opinions on this? It seems useful to enable > `round()` and is a bit of a shame to get caught up on the detail, but I > am not sure what the right choice is :). > > - Sebastian > > _______________________________________________ > NumPy-Discussion mailing list -- numpy-discussion@python.org > To unsubscribe send an email to numpy-discussion-le...@python.org > https://mail.python.org/mailman3/lists/numpy-discussion.python.org/ > Member address: asmeu...@gmail.com _______________________________________________ NumPy-Discussion mailing list -- numpy-discussion@python.org To unsubscribe send an email to numpy-discussion-le...@python.org https://mail.python.org/mailman3/lists/numpy-discussion.python.org/ Member address: arch...@mail-archive.com
