Mailman 3 September 2019 - NumPy-Discussion

Code review for adding axis argument to permutation and shuffle function
by Kexuan Sun Sept. 13, 2019

Sept. 13, 2019

Hi, I would like to request a code review. The random.permutation and random.shuffle functions now can only shuffle along the first axis of a multi-dimensional array. I propose to add an axis argument for the functions and allow them to shuffle along a given axis. Here is the link to the PR (https://github.com/numpy/numpy/pull/13829). Thanks!

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Re: [Numpy-discussion] round / set_printoptions discrepancy
by Stefano Miccoli Sept. 13, 2019

Sept. 13, 2019

In my opinion the problem is that numpy floats break the Liskov substitution principle, >>> pyfloat = 16.055 >>> npfloat = np.float64(pyfloat) >>> isinstance(npfloat, float) True >>> round(pyfloat, 2) 16.05 >>> round(npfloat, 2) 16.06 Since numpy.float64 is a subclass of builtins.float I would expect that >>> round(x, j) == round(np.float64(x), j) is an invariant, but unfortunately this is not the case. Moreover the python3 semantics … [View More]

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NumPy Community Survey
by Inessa Pawson Sept. 12, 2019

Sept. 12, 2019

You know that NumPy is essential to the Python community. The NumPy team wants you to know that YOU, our user and developer community, are essential to us. That’s why we are putting together a team to create the inaugural NumPy Community Survey. We hope feedback will provide insights that will help us to guide better decision-making about the development of NumPy as software and community. For more information about the proposed survey please refer to github.com/numpy/numpy-surveys . *Call for … [View More]

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Using hypothesis in testing
by Matti Picus Sept. 11, 2019

Sept. 11, 2019

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NEP 32: Remove the financial functions from NumPy
by Warren Weckesser Sept. 11, 2019

Sept. 11, 2019

Github issue 2880 ("Get financial functions out of main namespace", https://github.com/numpy/numpy/issues/2880) has been open since 2013. In a recent community meeting, it was suggested that we create a NEP to propose the removal of the financial functions from NumPy. I have submitted "NEP 32: Remove the financial functions from NumPy" in a pull request at https://github.com/numpy/numpy/pull/14399. A copy of the latest version of the NEP is below. According to the NEP process document, "… [View More]Once the PR is in place, the NEP should be announced on the mailing list for discussion (comments on the PR itself should be restricted to minor editorial and technical fixes)." This email is the announcement for NEP 32. The NEP includes a brief summary of the history of the financial functions, and has links to several relevant mailing list threads, dating back to when the functions were added to NumPy in 2008. I recommend reviewing those threads before commenting here. Warren ----- ================================================== NEP 32 — Remove the financial functions from NumPy ================================================== :Author: Warren Weckesser <warren.weckesser(a)gmail.com> :Status: Draft :Type: Standards Track :Created: 2019-08-30 Abstract -------- We propose deprecating and ultimately removing the financial functions [1]_ from NumPy. The functions will be moved to an independent repository, and provided to the community as a separate package with the name ``numpy_financial``. Motivation and scope -------------------- The NumPy financial functions [1]_ are the 10 functions ``fv``, ``ipmt``, ``irr``, ``mirr``, ``nper``, ``npv``, ``pmt``, ``ppmt``, ``pv`` and ``rate``. The functions provide elementary financial calculations such as future value, net present value, etc. These functions were added to NumPy in 2008 [2]_. In May, 2009, a request by Joe Harrington to add a function called ``xirr`` to the financial functions triggered a long thread about these functions [3]_. One important point that came up in that thread is that a "real" financial library must be able to handle real dates. The NumPy financial functions do not work with actual dates or calendars. The preference for a more capable library independent of NumPy was expressed several times in that thread. In June, 2009, D. L. Goldsmith expressed concerns about the correctness of the implementations of some of the financial functions [4]_. It was suggested then to move the financial functions out of NumPy to an independent package. In a GitHub issue in 2013 [5]_, Nathaniel Smith suggested moving the financial functions from the top-level namespace to ``numpy.financial``. He also suggested giving the functions better names. Responses at that time included the suggestion to deprecate them and move them from NumPy to a separate package. This issue is still open. Later in 2013 [6]_, it was suggested on the mailing list that these functions be removed from NumPy. The arguments for the removal of these functions from NumPy: * They are too specialized for NumPy. * They are not actually useful for "real world" financial calculations, because they do not handle real dates and calendars. * The definition of "correctness" for some of these functions seems to be a matter of convention, and the current NumPy developers do not have the background to judge their correctness. * There has been little interest among past and present NumPy developers in maintaining these functions. The main arguments for keeping the functions in NumPy are: * Removing these functions will be disruptive for some users. Current users will have to add the new ``numpy_financial`` package to their dependencies, and then modify their code to use the new package. * The functions provided, while not "industrial strength", are apparently similar to functions provided by spreadsheets and some calculators. Having them available in NumPy makes it easier for some developers to migrate their software to Python and NumPy. It is clear from comments in the mailing list discussions and in the GitHub issues that many current NumPy developers believe the benefits of removing the functions outweigh the costs. For example, from [5]_:: The financial functions should probably be part of a separate package -- Charles Harris If there's a better package we can point people to we could just deprecate them and then remove them entirely... I'd be fine with that too... -- Nathaniel Smith +1 to deprecate them. If no other package exists, it can be created if someone feels the need for that. -- Ralf Gommers I feel pretty strongly that we should deprecate these. If nobody on numpy’s core team is interested in maintaining them, then it is purely a drag on development for NumPy. -- Stephan Hoyer And from the 2013 mailing list discussion, about removing the functions from NumPy:: I am +1 as well, I don't think they should have been included in the first place. -- David Cournapeau But not everyone was in favor of removal:: The fin routines are tiny and don't require much maintenance once written. If we made an effort (putting up pages with examples of common financial calculations and collecting those under a topical web page, then linking to that page from various places and talking it up), I would think they could attract users looking for a free way to play with financial scenarios. [...] So, I would say we keep them. If ours are not the best, we should bring them up to snuff. -- Joe Harrington For an idea of the maintenance burden of the financial functions, one can look for all the GitHub issues [7]_ and pull requests [8]_ that have the tag ``component: numpy.lib.financial``. One method for measuring the effect of removing these functions is to find all the packages on GitHub that use them. Such a search can be performed with the ``python-api-inspect`` service [9]_. A search for all uses of the NumPy financial functions finds just eight repositories. (See the comments in [5]_ for the actual SQL query.) Implementation -------------- * Create a new Python package, ``numpy_financial``, to be maintained in the top-level NumPy github organization. This repository will contain the definitions and unit tests for the financial functions. The package will be added to PyPI so it can be installed with ``pip``. * Deprecate the financial functions in the ``numpy`` namespace, beginning in NumPy version 1.18. Remove the financial functions from NumPy version 1.20. Backward compatibility ---------------------- The removal of these functions breaks backward compatibility, as explained earlier. The effects are mitigated by providing the ``numpy_financial`` library. Alternatives ------------ The following alternatives were mentioned in [5]_: * *Maintain the functions as they are (i.e. do nothing).* A review of the history makes clear that this is not the preference of many NumPy developers. A recurring comment is that the functions simply do not belong in NumPy. When that sentiment is combined with the history of bug reports and the ongoing questions about the correctness of the functions, the conclusion is that the cleanest solution is deprecation and removal. * *Move the functions from the ``numpy`` namespace to ``numpy.financial``.* This was the initial suggestion in [5]_. Such a change does not address the maintenance issues, and doesn't change the misfit that many developers see between these functions and NumPy. It causes disruption for the current users of these functions without addressing what many developers see as the fundamental problem. Discussion ---------- Links to past mailing list discussions, and to relevant GitHub issues and pull requests, have already been given. References and footnotes ------------------------ .. [1] Financial functions, https://numpy.org/doc/1.17/reference/routines.financial.html .. [2] Numpy-discussion mailing list, "Simple financial functions for NumPy", https://mail.python.org/pipermail/numpy-discussion/2008-April/032353.html .. [3] Numpy-discussion mailing list, "add xirr to numpy financial functions?", https://mail.python.org/pipermail/numpy-discussion/2009-May/042645.html .. [4] Numpy-discussion mailing list, "Definitions of pv, fv, nper, pmt, and rate", https://mail.python.org/pipermail/numpy-discussion/2009-June/043188.html .. [5] Get financial functions out of main namespace, https://github.com/numpy/numpy/issues/2880 .. [6] Numpy-discussion mailing list, "Deprecation of financial routines", https://mail.python.org/pipermail/numpy-discussion/2013-August/067409.html .. [7] ``component: numpy.lib.financial`` issues, https://github.com/numpy/numpy/issues?utf8=%E2%9C%93&q=is%3Aissue+label%3A%… .. [8] ``component: numpy.lib.financial`` pull request, https://github.com/numpy/numpy/pulls?utf8=%E2%9C%93&q=is%3Apr+label%3A%22co… .. [9] Quansight-Labs/python-api-inspect, https://github.com/Quansight-Labs/python-api-inspect/ Copyright --------- This document has been placed in the public domain. [View Less]

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NumPy Community Meeting Wednesday, Sep. 11
by Sebastian Berg Sept. 10, 2019

Sept. 10, 2019

Hi all, There will be a NumPy Community meeting Wednesday September 11 at 11 am Pacific Time. Everyone is invited to join in and edit the work-in- progress meeting topics and notes: https://hackmd.io/76o-IxCjQX2mOXO_wwkcpg?both Best wishes Sebastian

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[JOB] Principal Software Engineer position at IHME
by Chun-Wei Yuan Sept. 10, 2019

Sept. 10, 2019

*The Institute for Health Metrics and Evaluation (IHME) *has an outstanding opportunity for a full-time *Principal Software Engineer *on our Forecasting/Future Health Scenarios (FHS) team*.* The development arm of the team is responsible for the design and implementation of software to support this effort, and the Principal Software Engineer will lead the development work and supervise engineers on that team. IHME’s aim within the FHS portfolio is to create an analytic engine that can model the … [View More]

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shipping sdists without generated C sources from Cython code
by Ralf Gommers Sept. 8, 2019

Sept. 8, 2019

Hi all, There are several open issues about people not being able to compile the latest release with Python 3.8 betas due to our release containing generated C code with a too old version of Cython. This happened for Python 3.7 as well. With the Python packaging system having improved that build dependencies are no longer insane, I think we should stop shipping the generated C sources. We've discussed this a couple of times before on GitHub, but I've now opened a PR for this (https://github.… [View More]

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NumPy 1.17.2 released.
by Charles R Harris Sept. 6, 2019

Sept. 6, 2019

Hi All, On behalf of the NumPy team I am pleased to announce that NumPy 1.17.2 has been released. This release contains fixes for bugs reported against NumPy 1.17.1 along with some documentation improvements. The most important fix is for lexsort when the keys are of type (u)int8 or (u)int16. If you are currently using 1.17 you should upgrade. The Python versions supported in this release are 3.5-3.7, Python 3.8b4 should work with the released source packages, but there are no future … [View More]

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Proposal to accept NEP #29: Recommend Python and Numpy version support as a community policy standard
by Thomas Caswell Sept. 6, 2019

Sept. 6, 2019

https://numpy.org/neps/nep-0029-deprecation_policy.html The outstanding concern in https://github.com/numpy/numpy/pull/14086 was that some projects want to continue to support additional versions of Python and numpy outside of the minimum support windows. The language has been changed to specify that these are _minimum_ support windows and that projects _should_ not _will_ drop support as they can. There is one trivial wording change PR open ( https://github.com/numpy/numpy/pull/14444). If … [View More]

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1.17.2 release.
by Charles R Harris Sept. 5, 2019

Sept. 5, 2019

Hi All, I'm planning to make a 1.17.2 release Friday or Saturday in order to fix some newly reported regressions. If there is anything that you think absolutely needs to be in that release, please yell. Chuck

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Integer array indexing (numpy.take) as function composition
by Jim Pivarski Sept. 5, 2019

Sept. 5, 2019

Hi, I'm a long-time user of Numpy; I had a question and I didn't know where else to ask. (It's not a bug—otherwise I would have posted it at https://github.com/numpy/numpy/issues). Has anyone noticed that indexing an array with integer arrays (i.e. numpy.take) is a function composition? For example, suppose you have any two non-negative functions of integers: def f(x): return x**2 - 5*x + 10 def g(y): return max(0, 2*y - 10) + 3 and you sample them as arrays, as well as their … [View More]

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Re: [Numpy-discussion] NEP 32: Remove the financial functions from NumPy
by Martin.Gfeller＠swisscom.com Sept. 4, 2019

Sept. 4, 2019

Dear all As a user of Numpy in finance, I'm absolutely in favour of removing these functions. They're too domain-specific, not flexible and general enough for widespread use, and probably not easy to maintain. Best regards Martin

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NumPy Community Meeting Wednesday, Sep. 4
by Sebastian Berg Sept. 3, 2019

Sept. 3, 2019

Hi all, There will be a NumPy Community meeting Wednesday September 4 at 11 am Pacific Time. Everyone is invited to join in and edit the work-in- progress meeting topics and notes: https://hackmd.io/76o-IxCjQX2mOXO_wwkcpg?both Best wishes Sebastian

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Allowing Dependabot access to the numpy repo
by Matti Picus Sept. 1, 2019

Sept. 1, 2019

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