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<li class="toctree-l2 current active"><a class="current reference internal" href="#">NEP 0 — Purpose and process</a></li>
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<li class="toctree-l2"><a class="reference internal" href="nep-0036-fair-play.html">NEP 36 — Fair play</a></li>
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<li class="toctree-l2"><a class="reference internal" href="nep-0041-improved-dtype-support.html">NEP 41 — First step towards a new datatype system</a></li>
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<li class="toctree-l2"><a class="reference internal" href="nep-0001-npy-format.html">NEP 1 — A simple file format for NumPy arrays</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0005-generalized-ufuncs.html">NEP 5 — Generalized universal functions</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0007-datetime-proposal.html">NEP 7 — A proposal for implementing some date/time types in NumPy</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0010-new-iterator-ufunc.html">NEP 10 — Optimizing iterator/UFunc performance</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0013-ufunc-overrides.html">NEP 13 — A mechanism for overriding Ufuncs</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0014-dropping-python2.7-proposal.html">NEP 14 — Plan for dropping Python 2.7 support</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0015-merge-multiarray-umath.html">NEP 15 — Merging multiarray and umath</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0018-array-function-protocol.html">NEP 18 — A dispatch mechanism for NumPy's high level array functions</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0019-rng-policy.html">NEP 19 — Random number generator policy</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0020-gufunc-signature-enhancement.html">NEP 20 — Expansion of generalized universal function signatures</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0022-ndarray-duck-typing-overview.html">NEP 22 — Duck typing for NumPy arrays – high level overview</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0027-zero-rank-arrays.html">NEP 27 — Zero rank arrays</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0028-website-redesign.html">NEP 28 — numpy.org website redesign</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0029-deprecation_policy.html">NEP 29 — Recommend Python and NumPy version support as a community policy standard</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0032-remove-financial-functions.html">NEP 32 — Remove the financial functions from NumPy</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0034-infer-dtype-is-object.html">NEP 34 — Disallow inferring ``dtype=object`` from sequences</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0035-array-creation-dispatch-with-array-function.html">NEP 35 — Array creation dispatching with __array_function__</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0038-SIMD-optimizations.html">NEP 38 — Using SIMD optimization instructions for performance</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0040-legacy-datatype-impl.html">NEP 40 — Legacy datatype implementation in NumPy</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0049-data-allocation-strategies.html">NEP 49 — Data allocation strategies</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0050-scalar-promotion.html">NEP 50 — Promotion rules for Python scalars</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0052-python-api-cleanup.html">NEP 52 — Python API cleanup for NumPy 2.0</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0055-string_dtype.html">NEP 55 — Add a UTF-8 variable-width string DType to NumPy</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0056-array-api-main-namespace.html">NEP 56 — Array API standard support in NumPy's main namespace</a></li>
</ul>
</details></li>
<li class="toctree-l1 has-children"><a class="reference internal" href="deferred.html">Deferred and Superseded NEPs</a><details><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul>
<li class="toctree-l2"><a class="reference internal" href="nep-0002-warnfix.html">NEP 2 — A proposal to build numpy without warning with a big set of warning flags</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0003-math_config_clean.html">NEP 3 — Cleaning the math configuration of numpy.core</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0004-datetime-proposal3.html">NEP 4 — A (third) proposal for implementing some date/time types in NumPy</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0006-newbugtracker.html">NEP 6 — Replacing Trac with a different bug tracker</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0008-groupby_additions.html">NEP 8 — A proposal for adding groupby functionality to NumPy</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0009-structured_array_extensions.html">NEP 9 — Structured array extensions</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0011-deferred-ufunc-evaluation.html">NEP 11 — Deferred UFunc evaluation</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0012-missing-data.html">NEP 12 — Missing data functionality in NumPy</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0021-advanced-indexing.html">NEP 21 — Simplified and explicit advanced indexing</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0024-missing-data-2.html">NEP 24 — Missing data functionality - alternative 1 to NEP 12</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0025-missing-data-3.html">NEP 25 — NA support via special dtypes</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0026-missing-data-summary.html">NEP 26 — Summary of missing data NEPs and discussion</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0030-duck-array-protocol.html">NEP 30 — Duck typing for NumPy arrays - implementation</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0031-uarray.html">NEP 31 — Context-local and global overrides of the NumPy API</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0037-array-module.html">NEP 37 — A dispatch protocol for NumPy-like modules</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0047-array-api-standard.html">NEP 47 — Adopting the array API standard</a></li>
</ul>
</details></li>
<li class="toctree-l1 has-children"><a class="reference internal" href="rejected.html">Rejected and Withdrawn NEPs</a><details><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul>
<li class="toctree-l2"><a class="reference internal" href="nep-0016-abstract-array.html">NEP 16 — An abstract base class for identifying "duck arrays"</a></li>
<li class="toctree-l2"><a class="reference internal" href="nep-0017-split-out-maskedarray.html">NEP 17 — Split out masked arrays</a></li>
</ul>
</details></li>
</ul>
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<section id="nep-0-purpose-and-process">
<span id="nep00"></span><h1>NEP 0 — Purpose and process<a class="headerlink" href="#nep-0-purpose-and-process" title="Link to this heading">#</a></h1>
<dl class="field-list simple">
<dt class="field-odd">Author<span class="colon">:</span></dt>
<dd class="field-odd"><p>Jarrod Millman <<a class="reference external" href="mailto:millman%40berkeley.edu">millman<span>@</span>berkeley<span>.</span>edu</a>></p>
</dd>
<dt class="field-even">Status<span class="colon">:</span></dt>
<dd class="field-even"><p>Active</p>
</dd>
<dt class="field-odd">Type<span class="colon">:</span></dt>
<dd class="field-odd"><p>Process</p>
</dd>
<dt class="field-even">Created<span class="colon">:</span></dt>
<dd class="field-even"><p>2017-12-11</p>
</dd>
</dl>
<section id="what-is-a-nep">
<h2>What is a NEP?<a class="headerlink" href="#what-is-a-nep" title="Link to this heading">#</a></h2>
<p>NEP stands for NumPy Enhancement Proposal. A NEP is a design
document providing information to the NumPy community, or describing
a new feature for NumPy or its processes or environment. The NEP
should provide a concise technical specification of the feature and a
rationale for the feature.</p>
<p>We intend NEPs to be the primary mechanisms for proposing major new
features, for collecting community input on an issue, and for
documenting the design decisions that have gone into NumPy. The NEP
author is responsible for building consensus within the community and
documenting dissenting opinions.</p>
<p>Because the NEPs are maintained as text files in a versioned
repository, their revision history is the historical record of the
feature proposal <a class="footnote-reference brackets" href="#id3" id="id1" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a>.</p>
<section id="types">
<h3>Types<a class="headerlink" href="#types" title="Link to this heading">#</a></h3>
<p>There are three kinds of NEPs:</p>
<ol class="arabic simple">
<li><p>A <strong>Standards Track</strong> NEP describes a new feature or implementation
for NumPy.</p></li>
<li><p>An <strong>Informational</strong> NEP describes a NumPy design issue, or provides
general guidelines or information to the Python community, but does not
propose a new feature. Informational NEPs do not necessarily represent a
NumPy community consensus or recommendation, so users and implementers are
free to ignore Informational NEPs or follow their advice.</p></li>
<li><p>A <strong>Process</strong> NEP describes a process surrounding NumPy, or
proposes a change to (or an event in) a process. Process NEPs are
like Standards Track NEPs but apply to areas other than the NumPy
language itself. They may propose an implementation, but not to
NumPy’s codebase; they require community consensus. Examples include
procedures, guidelines, changes to the decision-making process, and
changes to the tools or environment used in NumPy development.
Any meta-NEP is also considered a Process NEP.</p></li>
</ol>
</section>
</section>
<section id="nep-workflow">
<h2>NEP workflow<a class="headerlink" href="#nep-workflow" title="Link to this heading">#</a></h2>
<p>The NEP process begins with a new idea for NumPy. It is highly
recommended that a single NEP contain a single key proposal or new
idea. Small enhancements or patches often don’t need
a NEP and can be injected into the NumPy development workflow with a
pull request to the NumPy <a class="reference external" href="https://github.com/numpy/numpy">repo</a>. The more focused the
NEP, the more successful it tends to be.
If in doubt, split your NEP into several well-focused ones.</p>
<p>Each NEP must have a champion—someone who writes the NEP using the style
and format described below, shepherds the discussions in the appropriate
forums, and attempts to build community consensus around the idea. The NEP
champion (a.k.a. Author) should first attempt to ascertain whether the idea is
suitable for a NEP. Posting to the numpy-discussion <a class="reference external" href="https://mail.python.org/mailman/listinfo/numpy-discussion">mailing list</a> is the best
way to go about doing this.</p>
<p>The proposal should be submitted as a draft NEP via a <a class="reference external" href="https://github.com/numpy/numpy/pulls">GitHub pull
request</a> to the <code class="docutils literal notranslate"><span class="pre">doc/neps</span></code> directory with the name <code class="docutils literal notranslate"><span class="pre">nep-<n>.rst</span></code>
where <code class="docutils literal notranslate"><span class="pre"><n></span></code> is an appropriately assigned four-digit number (e.g.,
<code class="docutils literal notranslate"><span class="pre">nep-0000.rst</span></code>). The draft must use the <a class="reference internal" href="nep-template.html"><span class="doc">NEP X — Template and instructions</span></a> file.</p>
<p>Once the PR for the NEP is in place, a post should be made to the
mailing list containing the sections up to “Backward compatibility”,
with the purpose of limiting discussion there to usage and impact.
Discussion on the pull request will have a broader scope, also including
details of implementation.</p>
<p>At the earliest convenience, the PR should be merged (regardless of
whether it is accepted during discussion). Additional PRs may be made
by the Author to update or expand the NEP, or by maintainers to set
its status, discussion URL, etc.</p>
<p>Standards Track NEPs consist of two parts, a design document and a
reference implementation. It is generally recommended that at least a
prototype implementation be co-developed with the NEP, as ideas that sound
good in principle sometimes turn out to be impractical when subjected to the
test of implementation. Often it makes sense for the prototype implementation
to be made available as PR to the NumPy repo (making sure to appropriately
mark the PR as a WIP).</p>
<section id="review-and-resolution">
<h3>Review and resolution<a class="headerlink" href="#review-and-resolution" title="Link to this heading">#</a></h3>
<p>NEPs are discussed on the mailing list. The possible paths of the
status of NEPs are as follows:</p>
<img alt="_images/nep-0000.png" src="_images/nep-0000.png" />
<p>All NEPs should be created with the <code class="docutils literal notranslate"><span class="pre">Draft</span></code> status.</p>
<p>Eventually, after discussion, there may be a consensus that the NEP
should be accepted – see the next section for details. At this point
the status becomes <code class="docutils literal notranslate"><span class="pre">Accepted</span></code>.</p>
<p>Once a NEP has been <code class="docutils literal notranslate"><span class="pre">Accepted</span></code>, the reference implementation must be
completed. When the reference implementation is complete and incorporated
into the main source code repository, the status will be changed to <code class="docutils literal notranslate"><span class="pre">Final</span></code>.</p>
<p>To allow gathering of additional design and interface feedback before
committing to long term stability for a language feature or standard library
API, a NEP may also be marked as “Provisional”. This is short for
“Provisionally Accepted”, and indicates that the proposal has been accepted for
inclusion in the reference implementation, but additional user feedback is
needed before the full design can be considered “Final”. Unlike regular
accepted NEPs, provisionally accepted NEPs may still be Rejected or Withdrawn
even after the related changes have been included in a Python release.</p>
<p>Wherever possible, it is considered preferable to reduce the scope of a
proposal to avoid the need to rely on the “Provisional” status (e.g. by
deferring some features to later NEPs), as this status can lead to version
compatibility challenges in the wider NumPy ecosystem.</p>
<p>A NEP can also be assigned status <code class="docutils literal notranslate"><span class="pre">Deferred</span></code>. The NEP author or a
core developer can assign the NEP this status when no progress is being made
on the NEP.</p>
<p>A NEP can also be <code class="docutils literal notranslate"><span class="pre">Rejected</span></code>. Perhaps after all is said and done it
was not a good idea. It is still important to have a record of this
fact. The <code class="docutils literal notranslate"><span class="pre">Withdrawn</span></code> status is similar—it means that the NEP author
themselves has decided that the NEP is actually a bad idea, or has
accepted that a competing proposal is a better alternative.</p>
<p>When a NEP is <code class="docutils literal notranslate"><span class="pre">Accepted</span></code>, <code class="docutils literal notranslate"><span class="pre">Rejected</span></code>, or <code class="docutils literal notranslate"><span class="pre">Withdrawn</span></code>, the NEP should be
updated accordingly. In addition to updating the status field, at the very
least the <code class="docutils literal notranslate"><span class="pre">Resolution</span></code> header should be added with a link to the relevant
thread in the mailing list archives.</p>
<p>NEPs can also be <code class="docutils literal notranslate"><span class="pre">Superseded</span></code> by a different NEP, rendering the
original obsolete. The <code class="docutils literal notranslate"><span class="pre">Replaced-By</span></code> and <code class="docutils literal notranslate"><span class="pre">Replaces</span></code> headers
containing references to the original and new NEPs, like
<code class="docutils literal notranslate"><span class="pre">:ref:`NEP#number`</span></code> should be added respectively.</p>
<p>Process NEPs may also have a status of <code class="docutils literal notranslate"><span class="pre">Active</span></code> if they are never
meant to be completed, e.g. NEP 0 (this NEP).</p>
</section>
<section id="how-a-nep-becomes-accepted">
<h3>How a NEP becomes accepted<a class="headerlink" href="#how-a-nep-becomes-accepted" title="Link to this heading">#</a></h3>
<p>A NEP is <code class="docutils literal notranslate"><span class="pre">Accepted</span></code> by consensus of all interested contributors. We
need a concrete way to tell whether consensus has been reached. When
you think a NEP is ready to accept, send an email to the
numpy-discussion mailing list with a subject like:</p>
<blockquote>
<div><p>Proposal to accept NEP #<number>: <title></p>
</div></blockquote>
<p>In the body of your email, you should:</p>
<ul class="simple">
<li><p>link to the latest version of the NEP,</p></li>
<li><p>briefly describe any major points of contention and how they were
resolved,</p></li>
<li><p>include a sentence like: “If there are no substantive objections
within 7 days from this email, then the NEP will be accepted; see
NEP 0 for more details.”</p></li>
</ul>
<p>For an example, see: <a class="reference external" href="https://mail.python.org/pipermail/numpy-discussion/2018-June/078345.html">https://mail.python.org/pipermail/numpy-discussion/2018-June/078345.html</a></p>
<p>After you send the email, you should make sure to link to the email
thread from the <code class="docutils literal notranslate"><span class="pre">Discussion</span></code> section of the NEP, so that people can
find it later.</p>
<p>Generally the NEP author will be the one to send this email, but
anyone can do it – the important thing is to make sure that everyone
knows when a NEP is on the verge of acceptance, and give them a final
chance to respond. If there’s some special reason to extend this final
comment period beyond 7 days, then that’s fine, just say so in the
email. You shouldn’t do less than 7 days, because sometimes people are
travelling or similar and need some time to respond.</p>
<p>In general, the goal is to make sure that the community has consensus,
not provide a rigid policy for people to try to game. When in doubt,
err on the side of asking for more feedback and looking for
opportunities to compromise.</p>
<p>If the final comment period passes without any substantive objections,
then the NEP can officially be marked <code class="docutils literal notranslate"><span class="pre">Accepted</span></code>. You should send a
followup email notifying the list (celebratory emoji optional but
encouraged 🎉✨), and then update the NEP by setting its <code class="docutils literal notranslate"><span class="pre">:Status:</span></code>
to <code class="docutils literal notranslate"><span class="pre">Accepted</span></code>, and its <code class="docutils literal notranslate"><span class="pre">:Resolution:</span></code> header to a link to your
followup email.</p>
<p>If there <em>are</em> substantive objections, then the NEP remains in
<code class="docutils literal notranslate"><span class="pre">Draft</span></code> state, discussion continues as normal, and it can be
proposed for acceptance again later once the objections are resolved.</p>
<p>In unusual cases, the <a class="reference external" href="https://docs.scipy.org/doc/numpy/dev/governance/governance.html">NumPy Steering Council</a> may be asked to decide
whether a controversial NEP is <code class="docutils literal notranslate"><span class="pre">Accepted</span></code>.</p>
</section>
<section id="maintenance">
<h3>Maintenance<a class="headerlink" href="#maintenance" title="Link to this heading">#</a></h3>
<p>In general, Standards track NEPs are no longer modified after they have
reached the Final state as the code and project documentation are considered
the ultimate reference for the implemented feature.
However, finalized Standards track NEPs may be updated as needed.</p>
<p>Process NEPs may be updated over time to reflect changes
to development practices and other details. The precise process followed in
these cases will depend on the nature and purpose of the NEP being updated.</p>
</section>
</section>
<section id="format-and-template">
<h2>Format and template<a class="headerlink" href="#format-and-template" title="Link to this heading">#</a></h2>
<p>NEPs are UTF-8 encoded text files using the <a class="reference external" href="http://docutils.sourceforge.net/rst.html">reStructuredText</a> format. Please
see the <a class="reference internal" href="nep-template.html"><span class="doc">NEP X — Template and instructions</span></a> file and the <a class="reference external" href="http://www.sphinx-doc.org/en/stable/rest.html">reStructuredTextPrimer</a> for more
information. We use <a class="reference external" href="http://www.sphinx-doc.org/en/stable/">Sphinx</a> to convert NEPs to HTML for viewing on the web
<a class="footnote-reference brackets" href="#id4" id="id2" role="doc-noteref"><span class="fn-bracket">[</span>2<span class="fn-bracket">]</span></a>.</p>
<section id="header-preamble">
<h3>Header Preamble<a class="headerlink" href="#header-preamble" title="Link to this heading">#</a></h3>
<p>Each NEP must begin with a header preamble. The headers
must appear in the following order. Headers marked with <code class="docutils literal notranslate"><span class="pre">*</span></code> are
optional. All other headers are required.</p>
<div class="highlight-rst notranslate"><div class="highlight"><pre><span></span> <span class="nc">:Author:</span> <span class="nt"><list of authors' real names and optionally, email addresses></span>
<span class="nc">:Status:</span> <Draft | Active | Accepted | Deferred | Rejected |
Withdrawn | Final | Superseded>
<span class="nc">:Type:</span> <span class="nt"><Standards Track | Process></span>
<span class="nc">:Created:</span> <span class="nt"><date created on, in dd-mmm-yyyy format></span>
<span class="m">*</span> :Requires: <nep numbers>
<span class="m">*</span> :NumPy-Version: <version number>
<span class="m">*</span> :Replaces: <nep number>
<span class="m">*</span> :Replaced-By: <nep number>
<span class="m">*</span> :Resolution: <url>
</pre></div>
</div>
<p>The Author header lists the names, and optionally the email addresses
of all the authors of the NEP. The format of the Author header
value must be</p>
<div class="highlight-rst notranslate"><div class="highlight"><pre><span></span>Random J. User <address@dom.ain>
</pre></div>
</div>
<p>if the email address is included, and just</p>
<div class="highlight-rst notranslate"><div class="highlight"><pre><span></span>Random J. User
</pre></div>
</div>
<p>if the address is not given. If there are multiple authors, each should be on
a separate line.</p>
</section>
</section>
<section id="discussion">
<h2>Discussion<a class="headerlink" href="#discussion" title="Link to this heading">#</a></h2>
<ul class="simple">
<li><p><a class="reference external" href="https://mail.python.org/pipermail/numpy-discussion/2017-December/077481.html">https://mail.python.org/pipermail/numpy-discussion/2017-December/077481.html</a></p></li>
</ul>
</section>
<section id="references-and-footnotes">
<h2>References and footnotes<a class="headerlink" href="#references-and-footnotes" title="Link to this heading">#</a></h2>
<aside class="footnote-list brackets">
<aside class="footnote brackets" id="id3" role="doc-footnote">
<span class="label"><span class="fn-bracket">[</span><a role="doc-backlink" href="#id1">1</a><span class="fn-bracket">]</span></span>
<p>This historical record is available by the normal git commands
for retrieving older revisions, and can also be browsed on
<a class="reference external" href="https://github.com/numpy/numpy/tree/main/doc/neps">GitHub</a>.</p>
</aside>
<aside class="footnote brackets" id="id4" role="doc-footnote">
<span class="label"><span class="fn-bracket">[</span><a role="doc-backlink" href="#id2">2</a><span class="fn-bracket">]</span></span>
<p>The URL for viewing NEPs on the web is
<a class="reference external" href="https://www.numpy.org/neps/">https://www.numpy.org/neps/</a>.</p>
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<li class="toc-h2 nav-item toc-entry"><a class="reference internal nav-link" href="#what-is-a-nep">What is a NEP?</a><ul class="nav section-nav flex-column">
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