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DOC: Fixed links for np.show_runtime (numpy#21468)
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ganesh-k13 committed Aug 21, 2022
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8 changes: 4 additions & 4 deletions doc/release/upcoming_changes/21468.new_feature.rst
@@ -1,6 +1,6 @@
New function `np.show_runtime`
------------------------------
New function ``np.show_runtime``
--------------------------------

A new function `np.show_runtime` has been added to display the runtime
information of the machine in addition to `np.show_config` which displays
A new function `numpy.show_runtime` has been added to display the runtime
information of the machine in addition to `numpy.show_config` which displays
the build-related information.
293 changes: 293 additions & 0 deletions doc/source/release/2.25.0-notes.rst
@@ -0,0 +1,293 @@
==========================
NumPy 2.25.0 Release Notes
==========================


Expired deprecations
====================

* The ``normed`` keyword argument has been removed from
`np.histogram`, `np.histogram2d`, and `np.histogramdd`.
Use ``density`` instead. If ``normed`` was passed by
position, ``density`` is now used.

(`gh-21645 <https://github.com/numpy/numpy/pull/21645>`__)

* Ragged array creation will now always raise a ``ValueError`` unless
``dtype=object`` is passed. This includes very deeply nested sequences.

(`gh-22004 <https://github.com/numpy/numpy/pull/22004>`__)


Compatibility notes
===================

``array.fill(scalar)`` may behave slightly different
----------------------------------------------------
`~numpy.ndarray.fill` may in some cases behave slightly different
now due to the fact that the logic is aligned with item assignment::

arr = np.array([1]) # with any dtype/value
arr.fill(scalar)
# is now identical to:
arr[0] = scalar

Previously casting may have produced slightly different answers when using
values that could not be represented in the target ``dtype`` or when the
target had ``object`` dtype.

(`gh-20924 <https://github.com/numpy/numpy/pull/20924>`__)

Subarray to object cast now copies
----------------------------------
Casting a dtype that includes a subarray to an object will now ensure
a copy of the subarray. Previously an unsafe view was returned::

arr = np.ones(3, dtype=[("f", "i", 3)])
subarray_fields = arr.astype(object)[0]
subarray = subarray_fields[0] # "f" field

np.may_share_memory(subarray, arr)

Is now always false. While previously it was true for the specific cast.

(`gh-21925 <https://github.com/numpy/numpy/pull/21925>`__)


New Features
============

New attribute ``symbol`` added to polynomial classes
----------------------------------------------------

The polynomial classes in the ``numpy.polynomial`` package have a new
``symbol`` attribute which is used to represent the indeterminate
of the polynomial.
This can be used to change the value of the variable when printing::

>>> P_y = np.polynomial.Polynomial([1, 0, -1], symbol="y")
>>> print(P_y)
1.0 + 0.0·y¹ - 1.0·y²

Note that the polynomial classes only support 1D polynomials, so operations
that involve polynomials with different symbols are disallowed when the
result would be multivariate::

>>> P = np.polynomial.Polynomial([1, -1]) # default symbol is "x"
>>> P_z = np.polynomial.Polynomial([1, 1], symbol="z")
>>> P * P_z
Traceback (most recent call last)
...
ValueError: Polynomial symbols differ

The symbol can be any valid Python identifier. The default is ``symbol=x``,
consistent with existing behavior.

(`gh-16154 <https://github.com/numpy/numpy/pull/16154>`__)

F2PY support for Fortran ``character`` strings
----------------------------------------------
F2PY now supports wrapping Fortran functions with:

* character (e.g. ``character x``)
* character array (e.g. ``character, dimension(n) :: x``)
* character string (e.g. ``character(len=10) x``)
* and character string array (e.g. ``character(len=10), dimension(n, m) :: x``)

arguments, including passing Python unicode strings as Fortran character string arguments.

(`gh-19388 <https://github.com/numpy/numpy/pull/19388>`__)

New function `numpy.show_runtime`
------------------------------

A new function `numpy.show_runtime` has been added to display the runtime
information of the machine in addition to `numpy.show_config` which displays
the build-related information.

(`gh-21468 <https://github.com/numpy/numpy/pull/21468>`__)

``strict`` option for `testing.assert_array_equal`
--------------------------------------------------
The ``strict`` option is now available for `testing.assert_array_equal`.
Setting ``strict=True`` will disable the broadcasting behaviour for scalars and
ensure that input arrays have the same data type.

(`gh-21595 <https://github.com/numpy/numpy/pull/21595>`__)

New parameter ``equal_nan`` added to `np.unique`
------------------------------------------------

`np.unique` was changed in 1.21 to treat all ``NaN`` values as equal and return
a single ``NaN``. Setting ``equal_nan=False`` will restore pre-1.21 behavior
to treat ``NaNs`` as unique. Defaults to ``True``.

(`gh-21623 <https://github.com/numpy/numpy/pull/21623>`__)

``casting`` and ``dtype`` keyword arguments for `numpy.stack`
-------------------------------------------------------------
The ``casting`` and ``dtype`` keyword arguments are now available for `numpy.stack`.
To use them, write ``np.stack(..., dtype=None, casting='same_kind')``.


``casting`` and ``dtype`` keyword arguments for `numpy.vstack`
--------------------------------------------------------------
The ``casting`` and ``dtype`` keyword arguments are now available for `numpy.vstack`.
To use them, write ``np.vstack(..., dtype=None, casting='same_kind')``.


``casting`` and ``dtype`` keyword arguments for `numpy.hstack`
--------------------------------------------------------------
The ``casting`` and ``dtype`` keyword arguments are now available for `numpy.hstack`.
To use them, write ``np.hstack(..., dtype=None, casting='same_kind')``.

(`gh-21627 <https://github.com/numpy/numpy/pull/21627>`__)

The bit generator underlying the singleton RandomState can be changed
---------------------------------------------------------------------
The singleton ``RandomState`` instance exposed in the ``numpy.random`` module
is initialized at startup with the ``MT19937` bit generator. The new
function ``set_bit_generator`` allows the default bit generator to be
replaced with a user-provided bit generator. This function has been introduced
to provide a method allowing seamless integration of a high-quality, modern bit
generator in new code with existing code that makes use of the
singleton-provided random variate generating functions. The companion function
``get_bit_generator`` returns the current bit generator being used by the
singleton ``RandomState``. This is provided to simplify restoring
the original source of randomness if required.

The preferred method to generate reproducible random numbers is to use a modern
bit generator in an instance of ``Generator``. The function ``default_rng``
simplifies instantization.

>>> rg = np.random.default_rng(3728973198)
>>> rg.random()

The same bit generator can then be shared with the singleton instance so that
calling functions in the ``random`` module will use the same bit
generator.

>>> orig_bit_gen = np.random.get_bit_generator()
>>> np.random.set_bit_generator(rg.bit_generator)
>>> np.random.normal()

The swap is permanent (until reversed) and so any call to functions
in the ``random`` module will use the new bit generator. The original
can be restored if required for code to run correctly.

>>> np.random.set_bit_generator(orig_bit_gen)

(`gh-21976 <https://github.com/numpy/numpy/pull/21976>`__)


Improvements
============

F2PY Improvements
-----------------

* The generated extension modules don't use the deprecated NumPy-C API anymore
* Improved ``f2py`` generated exception messages
* Numerous bug and ``flake8`` warning fixes
* various CPP macros that one can use within C-expressions of signature files are prefixed with ``f2py_``. For example, one should use ``f2py_len(x)`` instead of ``len(x)``
* A new construct ``character(f2py_len=...)`` is introduced to support returning assumed length character strings (e.g. ``character(len=*)``) from wrapper functions

A hook to support rewriting ``f2py`` internal data structures after reading all its input files is introduced. This is required, for instance, for BC of SciPy support where character arguments are treated as character strings arguments in ``C`` expressions.

(`gh-19388 <https://github.com/numpy/numpy/pull/19388>`__)

IBM zSystems Vector Extension Facility (SIMD)
---------------------------------------------

Added support for SIMD extensions of zSystem (z13, z14, z15),
through the universal intrinsics interface. This support leads
to performance improvements for all SIMD kernels implemented
using the universal intrinsics, including the following operations:

rint, floor, trunc, ceil, sqrt, absolute, square, reciprocal, tanh, sin, cos,
equal, not_equal, greater, greater_equal, less, less_equal,
maximum, minimum, fmax, fmin, argmax, argmin,
add, subtract, multiply, divide.

(`gh-20913 <https://github.com/numpy/numpy/pull/20913>`__)

NumPy now gives floating point errors in casts
----------------------------------------------

In most cases, NumPy previously did not give floating point
warnings or errors when these happened during casts.
For examples, casts like::

np.array([2e300]).astype(np.float32) # overflow for float32
np.array([np.inf]).astype(np.int64)

Should now generally give floating point warnings. These warnings
should warn that floating point overflow occurred.
For errors when converting floating point values to integers users
should expect invalid value warnings.

Users can modify the behavior of these warnings using `np.errstate`.

Note that for float to int casts, the exact warnings that are given may
be platform dependend. For example::

arr = np.full(100, value=1000, dtype=np.float64)
arr.astype(np.int8)

May give a result equivalent to (the intermediat means no warning is given)::

arr.astype(np.int64).astype(np.int8)

May may return an undefined result, with a warning set::

RuntimeWarning: invalid value encountered in cast

The precise behavior if subject to the C99 standard and its implementation
in both software and hardware.

(`gh-21437 <https://github.com/numpy/numpy/pull/21437>`__)

F2PY supports the value attribute
=================================

The Fortran standard requires that variables declared with the ``value``
attribute must be passed by value instead of reference. F2PY now supports this
use pattern correctly. So ``integer, intent(in), value :: x`` in Fortran codes
will have correct wrappers generated.

(`gh-21807 <https://github.com/numpy/numpy/pull/21807>`__)

Added pickle support for third-party BitGenerators
==================================================

The pickle format for bit generators was extended to allow each bit generator
to supply its own constructor when during pickling. Previous versions of NumPy
only supported unpickling ``Generator`` instances created with one of the core set
of bit generators supplied with NumPy. Attempting to unpickle a ``Generator``
that used a third-party bit generators would fail since the constructor used during
the unpickling was only aware of the bit generators included in NumPy.

(`gh-22014 <https://github.com/numpy/numpy/pull/22014>`__)


Performance improvements and changes
====================================

Faster version of ``np.isin`` and ``np.in1d`` for integer arrays
----------------------------------------------------------------
``np.in1d`` (used by ``np.isin``) can now switch to a faster algorithm
(up to >10x faster) when it is passed two integer arrays.
This is often automatically used, but you can use ``kind="sort"`` or
``kind="table"`` to force the old or new method, respectively.

(`gh-12065 <https://github.com/numpy/numpy/pull/12065>`__)

Faster comparison operators
----------------------------
The comparison functions (``numpy.equal``, ``numpy.not_equal``, ``numpy.less``,
``numpy.less_equal``, ``numpy.greater`` and ``numpy.greater_equal``) are now
much faster as they are now vectorized with universal intrinsics. For a CPU
with SIMD extension AVX512BW, the performance gain is up to 2.57x, 1.65x and
19.15x for integer, float and boolean data types, respectively (with N=50000).

(`gh-21483 <https://github.com/numpy/numpy/pull/21483>`__)
8 changes: 4 additions & 4 deletions numpy/lib/utils.py
Expand Up @@ -29,10 +29,10 @@ def show_runtime():
Notes
-----
1. Information is derived with the help of `threadpoolctl`
library.
2. SIMD related information is derived from `__cpu_features__`,
`__cpu_baseline__` and `__cpu_dispatch__`
1. Information is derived with the help of `threadpoolctl
<https://pypi.org/project/threadpoolctl/>`_ library.
2. SIMD related information is derived from ``__cpu_features__``,
``__cpu_baseline__`` and ``__cpu_dispatch__``
Examples
--------
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