Stack is not a generalized ufunc. It may behave similar to one in many ways, but implementation wise has nothing to do with ufuncs. Also ufuncs do not support an arbitrary number of operands. `vectorize` can indeed mimic generalized ufuncs, but (unfortunately) doesn't create them as such currently. - Sebastian On Tue, 2024-12-31 at 10:20 -0600, Jim Pivarski via NumPy-Discussion wrote:
I think you're right: the function `stack`, as you've defined it, is a gufunc.
Here's an implementation using np.vectorize < https://numpy.org/doc/stable/reference/generated/numpy.vectorize.html> (rather than nb.vectorize <https://numba.readthedocs.io/en/stable/user/vectorize.html>). Since the signature is not "()->()" or "(),()->()" (or similar with a different number of scalar inputs and scalar outputs), it's a generalized ufunc.
def stack(a, b):
... broadcasts = np.broadcast_arrays(a, b)
... return np.stack(broadcasts, axis=-1)
...
stacky = np.vectorize(stack, signature="(),()->(2)")
stacky(np.arange(5), np.arange(5))
array([[0, 0],
[1, 1],
[2, 2],
[3, 3],
[4, 4]])
stacky(np.arange(5), np.array([[1], [2], [3], [4], [5]]))
array([[[0, 1],
[1, 1],
[2, 1],
[3, 1],
[4, 1]],
[[0, 2],
[1, 2],
[2, 2],
[3, 2],
[4, 2]],
[[0, 3],
[1, 3],
[2, 3],
[3, 3],
[4, 3]],
[[0, 4],
[1, 4],
[2, 4],
[3, 4],
[4, 4]],
[[0, 5],
[1, 5],
[2, 5],
[3, 5],
[4, 5]]])
On Tue, Dec 31, 2024 at 2:44 AM john.a.dawson--- via NumPy-Discussion < numpy-discussion@python.org> wrote:
Is the function `stack` above a gufunc? _______________________________________________ NumPy-Discussion mailing list -- numpy-discussion@python.org To unsubscribe send an email to numpy-discussion-leave@python.org https://mail.python.org/mailman3/lists/numpy-discussion.python.org/ Member address: jpivarski@gmail.com
_______________________________________________ NumPy-Discussion mailing list -- numpy-discussion@python.org To unsubscribe send an email to numpy-discussion-leave@python.org https://mail.python.org/mailman3/lists/numpy-discussion.python.org/ Member address: sebastian@sipsolutions.net