ENH: Increase np.atleast_2d and np.atleast_3d performance - #30880

I've got the results for the benchmark! 👍

Script: numpytest.py

import pyperf

runner = pyperf.Runner()

setup="""
import numpy as np
from numpy.polynomial import Polynomial

x = np.array([2, 3, 4])
y = np.array([2, 3])

p = Polynomial([1, 2, 3.])
"""   
runner.timeit(name=f"atleast_2d(1)", stmt=f"np.atleast_2d(1)", setup=setup)
runner.timeit(name=f"atleast_2d(x)", stmt=f"np.atleast_2d(x)", setup=setup)
runner.timeit(name=f"atleast_2d(1, x )", stmt=f"np.atleast_2d(1, x )", setup=setup)

runner.timeit(name=f"atleast_3d(1)", stmt=f"np.atleast_3d(1)", setup=setup)
runner.timeit(name=f"atleast_3d(x)", stmt=f"np.atleast_3d(x)", setup=setup)
runner.timeit(name=f"atleast_3d(1, x )", stmt=f"np.atleast_3d(1, x )", setup=setup)

runner.timeit(name=f"polyadd", stmt=f"np.polyadd(x, y)", setup=setup)

(Credits to @eendebakpt for the great script👍)

Results:

Old (numpy original):

atleast_2d(1): Mean +- std dev: 728 ns +- 21 ns
atleast_2d(x): Mean +- std dev: 575 ns +- 25 ns
atleast_2d(1, x ): Mean +- std dev: 1.16 us +- 0.07 us

atleast_3d(1): Mean +- std dev: 761 ns +- 42 ns
atleast_3d(x): Mean +- std dev: 635 ns +- 63 ns
atleast_3d(1, x ): Mean +- std dev: 1.17 us +- 0.04 us

polyadd: Mean +- std dev: 2.88 us +- 0.13 us

New (numpy by Benedikt Johannes):

atleast_2d(1): Mean +- std dev: 662 ns +- 43 ns
atleast_2d(x): Mean +- std dev: 488 ns +- 22 ns
atleast_2d(1, x ): Mean +- std dev: 1.12 us +- 0.05 us

atleast_3d(1): Mean +- std dev: 671 ns +- 22 ns
atleast_3d(x): Mean +- std dev: 512 ns +- 24 ns
atleast_3d(1, x ): Mean +- std dev: 1.15 us +- 0.06 us

polyadd: Mean +- std dev: 2.80 us +- 0.08 us

Test failure is unrealted (can't install build environment)

Should I write release notes 2.5 for this change, @ngoldbaum? Or is this done by the team? I only know this from CPython.

Because it says:

Beyond changes to a functions docstring and possible description in the general documentation, if your change introduces any user-facing modifications they may need to be mentioned in the release notes. To add your change to the release notes, you need to create a short file with a summary and place it in doc/release/upcoming_changes. The file doc/release/upcoming_changes/README.rst details the format and filename conventions.

And the change is kind of user facing in my opinion because the performance is changed and users might notice this (and the latest news document also includes performance improvements).

minor performance improvements like this don't need a release note

All checks pass, do I need to use any command like /merge?

So without the unrelated one

Please be patient, I added the milestone so this won't get lost before the next major release this summer.

Thank you!

But one question: Is everything finished that I got to do? So can I just wait for the summer without doing anything for this?

Maybe sooner, this PR has only been open for a day or so. The project doesn't move terribly quickly and people do code review as their time and interest permits.

I was also planning to look closer at this at some point. Usually we like to leave PRs that make performance improvements and add new features open for at least a few days.

Also, IMO this PR shouldn't be backported, so in practice very few people will be able to use this until NumPy 2.5 comes out this summer.

Ah, okay, thank you very much for the Information! Don’t feel stressed about it!

It's been seven months so it might make sense to make a new PR if the OP has gone on to other projects.

@ngoldbaum @eendebakpt I‘m still here 🙂👍 I always wanted to get this done and merged, it’s just that I didn’t Post anything here anymore because You Said I should not be so pushy, so no Problem, we can add this Suggestion by @eendebakpt, thank you by the way for the good idea

@eendebakpt thanks for the Like, but I think you didn’t See the comment above concerning my question to your Suggestion

@eendebakpt which axis should be -1 in 3d then? I‘m sorry, Im Not quite sure about your Suggestion, so Could you maybe do This Addition in a seperate PR then and get this merged at First because its a Bit offtopic or could you maybe explain a Bit why this change is correct in 2d and in what Form it could be correct for 3d? Thanks!

@eendebakpt which axis should be -1 in 3d then? I‘m sorry, Im Not quite sure about your Suggestion, so Could you maybe do This Addition in a seperate PR then and get this merged at First because its a Bit offtopic or could you maybe explain a Bit why this change is correct in 2d and in what Form it could be correct for 3d? Thanks!

Lets keep the changes out for this PR (I did not check the 3d case, maybe that is not so easy as the 2d case)

Perfect, thanks, then ready for merge

@ngoldbaum this PR is Open since 7 months, do you think that it’s maybe possible to get this merged soon, please?

And ready for Review

I'm on vacation this week.

If you'd like to get maintainer attention, I invite you to come to one of our weekly video calls
or to send a message to the mailing list.

Oh, sorry @ngoldbaum, didnt want to interrupt you! Thanks for the Information and have a Nice vacation!