[issue27181] Add geometric mean to `statistics` module

Raymond Hettinger added the comment: Feel free to reopen this if something further needed to be changed or discussed. -- resolution: -> fixed stage: patch review -> resolved status: open -> closed ___ Python tracker

[issue27181] Add geometric mean to `statistics` module

Raymond Hettinger added the comment: New changeset 6463ba3061bd311413d2951dc83c565907e10459 by Raymond Hettinger in branch 'master': bpo-27181: Add statistics.geometric_mean() (GH-12638) https://github.com/python/cpython/commit/6463ba3061bd311413d2951dc83c565907e10459 --

[issue27181] Add geometric mean to `statistics` module

Raymond Hettinger added the comment: Steven, how does this look? https://patch-diff.githubusercontent.com/raw/python/cpython/pull/12638.diff -- ___ Python tracker ___

[issue27181] Add geometric mean to `statistics` module

Change by Raymond Hettinger : -- keywords: +patch pull_requests: +12570 ___ Python tracker ___ ___ Python-bugs-list mailing list

[issue27181] Add geometric mean to `statistics` module

Raymond Hettinger added the comment: > On the basis that something is better than nothing, go ahead. > We can discuss accuracy and speed issues later. Thanks. I'll put together a PR for your consideration. -- ___ Python tracker

[issue27181] Add geometric mean to `statistics` module

Change by STINNER Victor : -- nosy: -vstinner ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue27181] Add geometric mean to `statistics` module

Steven D'Aprano added the comment: > In the spirit of "perfect is the enemy of good", would it be > reasonable to start with a simple, fast implementation using > exp-mean-log? Then if someone wants to make it more accurate later, > they can do so. I think that is a reasonable idea. On

[issue27181] Add geometric mean to `statistics` module

Raymond Hettinger added the comment: Almost three years have passed. In the spirit of "perfect is the enemy of good", would it be reasonable to start with a simple, fast implementation using exp-mean-log? Then if someone wants to make it more accurate later, they can do so. In some quick

[issue27181] Add geometric mean to `statistics` module

Change by Ned Deily : -- nosy: -ned.deily ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue27181] Add geometric mean to `statistics` module

Raymond Hettinger added the comment: > Updating the version in case this wanted to be considered for 3.8. Yes. It would be nice to get this wrapped-up. -- ___ Python tracker

[issue27181] Add geometric mean to `statistics` module

Cheryl Sabella added the comment: Updating the version in case this wanted to be considered for 3.8. -- versions: +Python 3.8 -Python 3.7 ___ Python tracker ___

[issue27181] Add geometric mean to `statistics` module

Cheryl Sabella added the comment: I was wondering if this has been taken up again for 3.7? Thanks! -- nosy: +csabella ___ Python tracker ___

[issue27181] Add geometric mean to `statistics` module

Ned Deily added the comment: Thanks, Steven. Actually, we needed to remove geometric_mean from the 3.6 branch, not the default branch (which will become 3.7). I backported your removal patch to 3.6. Feel free to reapply geometric_mean to the default branch at your leisure. --

[issue27181] Add geometric mean to `statistics` module

Roundup Robot added the comment: New changeset de0fa478c22e by Steven D'Aprano in branch '3.6': Issue #27181 remove geometric_mean and defer for 3.7. https://hg.python.org/cpython/rev/de0fa478c22e -- ___ Python tracker

[issue27181] Add geometric mean to `statistics` module

Roundup Robot added the comment: New changeset 9dce0e41bedd by Steven D'Aprano in branch 'default': Issue #27181 remove geometric_mean and defer for 3.7. https://hg.python.org/cpython/rev/9dce0e41bedd -- ___ Python tracker

[issue27181] Add geometric mean to `statistics` module

Steven D'Aprano added the comment: I'm sorry to say that due to technical difficulties, geometric mean is not going to be in a fit state for beta 2 of 3.6, and so is going to be removed and delayed until 3.7. -- priority: release blocker -> versions: +Python 3.7 -Python 3.6

[issue27181] Add geometric mean to `statistics` module

Steven D'Aprano added the comment: On Mon, Sep 12, 2016 at 03:35:14PM +, Mark Dickinson wrote: > statistics.geometric_mean(0.7 for _ in range(5000)) I've raised a new ticket #28111 -- ___ Python tracker

[issue27181] Add geometric mean to `statistics` module

STINNER Victor added the comment: >>> statistics.geometric_mean([0.7 for _ in range(5000)]) Traceback (most recent call last): File "/Users/mdickinson/Python/cpython-git/Lib/statistics.py", line 362, in float_nroot isinfinity = math.isinf(x) OverflowError: int too large to convert to

[issue27181] Add geometric mean to `statistics` module

Mark Dickinson added the comment: Steven: any thoughts about the statistics.geometric_mean(0.7 for _ in range(5000)) failure? Should I open a separate bug report for that, or would you rather address it as part of this issue? -- ___ Python tracker

[issue27181] Add geometric mean to `statistics` module

Steven D'Aprano added the comment: As discussed with Ned by email, I'm currently unable to build 3.6 and won't have time to work on this before b1. As discussed on #27761 my tests here are too strict and should be loosened, e.g. from assertEqual to assertAlmostEqual. Ned wrote: "If you are

[issue27181] Add geometric mean to `statistics` module

Mark Dickinson added the comment: > self.assertEqual(self.nroot(x**12, 12), float(x)) > AssertionError: 1.1865 != 1.1868 That looks like a case where the test should simply be weakened to an `assertAlmostEqual` with a suitable tolerance; there's no strong reason to

[issue27181] Add geometric mean to `statistics` module

koobs added the comment: For posterity, the following failure was observed on all (9/10/11(current) FreeBSD buildbots: == FAIL: testFraction (test.test_statistics.Test_Nth_Root)

[issue27181] Add geometric mean to `statistics` module

STINNER Victor added the comment: I would like to use buildbots to check for regressions, but I see a lot of red buildbots, so buildbots became useless :-/ I skipped failing test_statistics tests, since failures are known. I put the priority to "release blocker". I suggest to either revert

[issue27181] Add geometric mean to `statistics` module

Roundup Robot added the comment: New changeset 54288b160243 by Victor Stinner in branch 'default': Issue #27181: Skip tests known to fail until a fix is found https://hg.python.org/cpython/rev/54288b160243 -- ___ Python tracker

[issue27181] Add geometric mean to `statistics` module

STINNER Victor added the comment: Failure on s390x Debian 3.x: http://buildbot.python.org/all/builders/s390x%20Debian%203.x/builds/1455/steps/test/logs/stdio == FAIL: testExactPowers (test.test_statistics.Test_Nth_Root) (i=29,

[issue27181] Add geometric mean to `statistics` module

Ned Deily added the comment: FTR, multiple platforms are failing in various ways, not just PPC64, so Issue27761 was expanded to cover them and has been marked as a "release blocker". -- nosy: +ned.deily ___ Python tracker

[issue27181] Add geometric mean to `statistics` module

Mark Dickinson added the comment: A failing case: >>> statistics.geometric_mean([0.7 for _ in range(5000)]) Traceback (most recent call last): File "/Users/mdickinson/Python/cpython-git/Lib/statistics.py", line 362, in float_nroot isinfinity = math.isinf(x) OverflowError: int too large

[issue27181] Add geometric mean to `statistics` module

Steven D'Aprano added the comment: I've created a new issue to track the loss of accuracy on PowerPC: http://bugs.python.org/issue27761 -- ___ Python tracker

[issue27181] Add geometric mean to `statistics` module

Mark Dickinson added the comment: > According to my testing, math.pow(x, 0.5) is no worse than sqrt. It certainly is worse than sqrt, both in terms of speed and accuracy. Whether the difference is enough to make it worth special-casing is another question, of course, and as you say, that can

[issue27181] Add geometric mean to `statistics` module

Steven D'Aprano added the comment: I thought about special-casing n=2 to math.sqrt, but as that's an implementation detail I can make that change at any time. According to my testing, math.pow(x, 0.5) is no worse than sqrt, so I'm not sure if there's any advantage to having yet another

[issue27181] Add geometric mean to `statistics` module

Mark Dickinson added the comment: What no patch for pre-commit review?! For computing nth roots, it may be worth special-casing the case n=2: for floats, `math.sqrt` is likely to be faster and more precise than an ad-hoc algorithm. (Indeed, I'd expect it to be perfectly correctly rounded on

[issue27181] Add geometric mean to `statistics` module

Martin Panter added the comment: Tests fail on a Power PC buildbot: http://buildbot.python.org/all/builders/PPC64LE%20Fedora%203.x/builds/1476/steps/test/logs/stdio == FAIL: testExactPowers (test.test_statistics.Test_Nth_Root)

[issue27181] Add geometric mean to `statistics` module

Ram Rachum added the comment: I meant the mathematical definition. -- ___ Python tracker ___ ___

[issue27181] Add geometric mean to `statistics` module

Steven D'Aprano added the comment: On Tue, Aug 09, 2016 at 06:44:22AM +, Ram Rachum wrote: > For `geometric_mean`, maybe I'd add one sentence that describes > how the geometric mean is calculated. What do you mean? As in, the mathematical definition of geometric mean? Or do you mean a one

[issue27181] Add geometric mean to `statistics` module

Ram Rachum added the comment: Also... I like the detailed docstrings with the real-life examples! That stuff helps when coding and using an unfamiliar function (since I see the docs in a panel of my IDE), so I wish I'd see more detailed docstrings like these ones in the standard library. For

[issue27181] Add geometric mean to `statistics` module

Ram Rachum added the comment: Thanks for the patch Steven! I won't comment about the code because I don't know enough about these algorithms, but I'm thinking, since you also did a refactoring of the statistics module, maybe these should be two separate patches/commits so it'll be easy to see

[issue27181] Add geometric mean to `statistics` module

Roundup Robot added the comment: New changeset 9eb5edfcf604 by Steven D'Aprano in branch 'default': Issue27181 add geometric mean. https://hg.python.org/cpython/rev/9eb5edfcf604 -- nosy: +python-dev ___ Python tracker

[issue27181] Add geometric mean to `statistics` module

Mark Dickinson added the comment: > I would like to see them spelled-out: geometric_mean and harmonic_mean +1 -- ___ Python tracker ___

[issue27181] Add geometric mean to `statistics` module

Raymond Hettinger added the comment: I would like to see them spelled-out: geometric_mean and harmonic_mean -- ___ Python tracker ___

[issue27181] Add geometric mean to `statistics` module

Steven D'Aprano added the comment: Does anyone have any strong feeling about the name for these functions? gmean and hmean; geometric_mean and harmonic_mean And "subcontrary_mean" is not an option :-) -- ___ Python tracker

[issue27181] Add geometric mean to `statistics` module

Mark Dickinson added the comment: > Hmm, well, I don't have SciPy installed, but I've found that despite > their (well-deserved) reputation, numpy (and presumably scipy) often > have rather naive algorithms that can lose accuracy rather > spectacularly. Agreed. And as Ram Rachum hinted,

[issue27181] Add geometric mean to `statistics` module

Steven D'Aprano added the comment: On Thu, Jun 09, 2016 at 09:24:04AM +, Mark Dickinson wrote: > On the other hand, apparently `exp(mean(log(...)))` is good enough for SciPy: Hmm, well, I don't have SciPy installed, but I've found that despite their (well-deserved) reputation, numpy (and

[issue27181] Add geometric mean to `statistics` module

Mark Dickinson added the comment: On the other hand, apparently `exp(mean(log(...)))` is good enough for SciPy: its current implementation looks like this: def gmean(a, axis=0): a, axis = _chk_asarray(a, axis) log_a = ma.log(a) return ma.exp(log_a.mean(axis=axis)) --

[issue27181] Add geometric mean to `statistics` module

Mark Dickinson added the comment: Choice of algorithm is a bit tricky here. There are a couple of obvious algorithms that work mathematically but result in significant accuracy loss in an IEEE 754 floating-point implementation: one is `exp(mean(map(log, my_numbers)))`, where the log calls can

[issue27181] Add geometric mean to `statistics` module

Ram Rachum added the comment: And of course, if the goal of the `statistics` module is to be comprehensive, one should ask himself what should be the difference between this new module and a mature statistics module like `scipy.stats`, and whether we should try to copy the features of off

[issue27181] Add geometric mean to `statistics` module

Ram Rachum added the comment: To complicate things further... I implemented a geometric mean on my own, and then I figured out what I really want is a *weighted* geometric mean, so I implemented that for myself. If you'd want to include that, that'll be cool. Actually I'm not sure if the goal

[issue27181] Add geometric mean to `statistics` module

Steven D'Aprano added the comment: On Thu, Jun 02, 2016 at 09:04:54PM +, Raymond Hettinger wrote: > Steven, this seems like a reasonable suggestion (though I would expect > someone else will immediately suggest a harmonic mean as well). Is > this within the scope of what you were trying

[issue27181] Add geometric mean to `statistics` module

New submission from Raymond Hettinger: Steven, this seems like a reasonable suggestion (though I would expect someone else will immediately suggest a harmonic mean as well). Is this within the scope of what you were trying to do with the statistics module? -- assignee: ->

[issue27181] Add geometric mean to `statistics` module

Changes by Xiang Zhang : -- nosy: +steven.daprano ___ Python tracker ___ ___

[issue27181] Add geometric mean to `statistics` module

Changes by Ram Rachum : -- components: Library (Lib) nosy: cool-RR priority: normal severity: normal status: open title: Add geometric mean to `statistics` module type: enhancement versions: Python 3.6 ___ Python tracker