[Numpy-discussion] Re: Add a bit_width function
Hi all, I am not as such against adding more bit-wise functions. But, I think if we do, we probably need to discuss namespaces. (because adding this is a slippery slope to also adding countr/countl, etc. Unless we can just decide now to add all and those are actually few.) True, `bitwise_` naming convention is similar, but there is always concern about the main namespace being too big to add functions that don't have wide application. (Or in other words maybe: Without that, there may need to be a strong argument that this function will be used enough to be worthwhile.) (There was some old discussion around this when we added `bitwise_count`, but may be old enough to not be all that interesting anymore.) Also always good to mention that it is very easy to create a small package with a family of bitwise functions outside of NumPy, like e.g. `ufunclab` [1]. (And the numpy docs could link to it in the "See also" section for example.) - Sebastian [1] https://github.com/WarrenWeckesser/ufunclab On Thu, 2025-03-06 at 18:08 +, Carlos Martin wrote: > Feature request: Add a `bit_width` function to NumPy's [bit-wise > operations]( > https://numpy.org/doc/stable/reference/routines.bitwise.html) that > computes the [bit-width](https://en.wikipedia.org/wiki/Bit-width) > (also called bit-length) of an input. > > For an example, see C++'s > [`bit_width`](https://en.cppreference.com/w/cpp/numeric/bit_width) > function. > ___ > 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: sebast...@sipsolutions.net > ___ 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
[Numpy-discussion] Re: Add a bit_width function
On Thu, 6 Mar 2025 at 18:12, Carlos Martin wrote: > > Feature request: Add a `bit_width` function to NumPy In Python this is called bit_length: >>> (7).bit_length() 3 ___ 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
[Numpy-discussion] Re: Add a bit_width function
Hi Stefan, It should work on unsigned integer types and use exact computation (not floating-point computations like np.log2). For an example, see https://graphics.stanford.edu/~seander/bithacks.html#IntegerLogDeBruijn. ___ 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
[Numpy-discussion] Add a bit_width function
Feature request: Add a `bit_width` function to NumPy's [bit-wise operations](https://numpy.org/doc/stable/reference/routines.bitwise.html) that computes the [bit-width](https://en.wikipedia.org/wiki/Bit-width) (also called bit-length) of an input. For an example, see C++'s [`bit_width`](https://en.cppreference.com/w/cpp/numeric/bit_width) function. ___ 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
[Numpy-discussion] Re: Add a bit_width function
Hi Carlos, On Thu, Mar 6, 2025, at 10:08, Carlos Martin wrote: > Feature request: Add a `bit_width` function to NumPy's [bit-wise > operations](https://numpy.org/doc/stable/reference/routines.bitwise.html) > that computes the [bit-width](https://en.wikipedia.org/wiki/Bit-width) > (also called bit-length) of an input. I'm curious, would this be roughly: def bit_width(x): y = np.zeros(len(x), dtype=float) mask = (x != 0) y[mask] = 1 + np.floor(np.log2(x[mask])) return y plus some error checking to ensure you don't run it on unsigned or floating point types? Stéfan ___ 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
