Update numpy to 1.16.0

[pyup-bot]

This PR updates numpy from 1.15.4 to 1.16.0.

Changelog

1.16.0

==========================

This NumPy release is the last one to support Python 2.7. It will be maintained
as a long term release with bug fixes only through 2020. To that end, the
planned code reorganization detailed in `NEP 15`_ has been made in order to
facilitate backporting fixes from future releases, which will now have the
same code organization.

Support for Python 3.4 been dropped in this release, the supported Python
versions are 2.7 and 3.5-3.7. The wheels are linked with OpenBLAS v0.3.0 .


Highlights
==========


New functions
=============

* New functions in the `numpy.lib.recfunctions` module to ease the structured
assignment changes: `assign_fields_by_name`, `structured_to_unstructured`,
`unstructured_to_structured`, `apply_along_fields`, and `require_fields`.
See the user guide at <https://docs.scipy.org/doc/numpy/user/basics.rec.html>
for more info.

Deprecations
============

`typeNA` and `sctypeNA` have been deprecated
--------------------------------------------

The type dictionaries `numpy.core.typeNA` and `numpy.core.sctypeNA` were buggy
and not documented. They will be removed in the 1.18 release. Use
`numpy.sctypeDict` instead.


``np.PackageLoader`` and ``np.pkgload`` have been removed
---------------------------------------------------------
These were deprecated in 1.10, had no tests, and seem to no longer work in
1.15 anyway.

`numpy.asscalar` has been deprecated
------------------------------------
It is an alias to the more powerful `numpy.ndarray.item`, not tested, and fails
for scalars.

`np.set_array_ops` and `np.get_array_ops` have been deprecated
--------------------------------------------------------------
As part of `NEP 15`, they have been deprecated along with the C-API functions
:c:func:`PyArray_SetNumericOps` and :c:func:`PyArray_GetNumericOps`. Users who wish to override
the inner loop functions in built-in ufuncs should use
:c:func:`PyUFunc_ReplaceLoopBySignature`.

Future Changes
==============

* NumPy 1.17 will drop support for Python 2.7.

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

* NaT comparisons now return ``False`` without a warning, finishing a
deprecation cycle begun in NumPy 1.11.

* ``np.lib.function_base.unique`` was removed, finishing a deprecation cycle
begun in NumPy 1.4. Use `numpy.unique` instead.

* multi-field indexing now returns views instead of copies, finishing a
deprecation cycle begun in NumPy 1.7. The change was previously attempted in
NumPy 1.14 but reverted until now.

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

f2py script on Windows
----------------------
On Windows, the installed script for running f2py is now an ``.exe`` file
rather than a ``*.py`` file and should be run from the command line as ``f2py``
whenever the ``Scripts`` directory is in the path. Folks needing compatibility
with earler versions of Numpy should run ``f2py`` as a module: ``python -m
numpy.f2py [...]``.

NaT comparisons
---------------
Consistent with the behavior of NaN, all comparisons other than inequality
checks with datetime64 or timedelta64 NaT ("not-a-time") values now always
return ``False``, and inequality checks with NaT now always return ``True``.
This includes comparisons beteween NaT values. For compatibility with the
old behavior, use ``np.isnat`` to explicitly check for NaT or convert
datetime64/timedelta64 arrays with ``.astype(np.int64)`` before making
comparisons.

complex64/128 alignment has changed
-----------------------------------
The memory alignment of complex types is now the same as a C-struct composed of
two floating point values, while before it was equal to the size of the type.
For many users (for instance on x64/unix/gcc) this means that complex64 is now
4-byte aligned instead of 8-byte aligned. An important consequence is that
aligned structured dtypes may now have a different size. For instance,
``np.dtype('c8,u1', align=True)`` used to have an itemsize of 16 (on x64/gcc)
but now it is 12.

More in detail, the complex64 type now has the same alignment as a C-struct
``struct {float r, i;}``, according to the compiler used to compile numpy, and
similarly for the complex128 and complex256 types.

nd_grid __len__ removal
-----------------------
``len(np.mgrid)`` and ``len(np.ogrid)`` are now considered nonsensical
and raise a ``TypeError``.

``np.unravel_index`` now accepts ``shape`` keyword argument
-----------------------------------------------------------
Previously, only the ``dims`` keyword argument was accepted
for specification of the shape of the array to be used
for unraveling. ``dims`` remains supported, but is now deprecated.

multi-field views return a view instead of a copy
-------------------------------------------------
Indexing a structured array with multiple fields, e.g.,
``arr[['f1', 'f3']]``, returns a view into the original array instead of a
copy. The returned view will often have extra padding bytes corresponding to
intervening fields in the original array, unlike before, which will
affect code such as ``arr[['f1', 'f3']].view('float64')``. This change has
been planned since numpy 1.7 and such operations have emitted
``FutureWarnings`` since then and more since 1.12.

To help users update their code to account for these changes, a number of
functions have been added to the ``numpy.lib.recfunctions`` module which
safely allow such operations. For instance, the code above can be replaced
with ``structured_to_unstructured(arr[['f1', 'f3']], dtype='float64')``.
See the "accessing multiple fields" section of the
`user guide <https://docs.scipy.org/doc/numpy/user/basics.rec.html>`__.


C API changes
=============

The :c:data:`NPY_API_VERSION` was incremented to 0x0000D, due to the addition
of:

* :c:member:`PyUFuncObject.core_dim_flags`
* :c:member:`PyUFuncObject.core_dim_sizes`
* :c:member:`PyUFuncObject.identity_value`
* :c:function:`PyUFunc_FromFuncAndDataAndSignatureAndIdentity`

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

Integrated squared error (ISE) estimator added to ``histogram``
---------------------------------------------------------------
This method (``bins='stone'``) for optimizing the bin number is a generalization of the
Scott's rule. The Scott's rule assumes the distribution is approximately
Normal, while the ISE is a nonparametric method based on cross-validation.
https://en.wikipedia.org/wiki/HistogramMinimizing_cross-validation_estimated_squared_error

``max_rows`` keyword added for ``np.loadtxt``
---------------------------------------------
New keyword ``max_rows`` in `numpy.loadtxt` sets the maximum rows of the
content to be read after ``skiprows``, as in `numpy.genfromtxt`.

modulus operator support added for ``np.timedelta64`` operands
--------------------------------------------------------------
The modulus (remainder) operator is now supported for two operands
of type ``np.timedelta64``. The operands may have different units
and the return value will match the type of the operands.


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

no-copy pickling of numpy arrays
--------------------------------
Up to protocol 4, numpy array pickling created 2 spurious copies of the data
being serlialized.
With pickle protocol 5, and the ``PickleBuffer`` API, a large variety of numpy
arrays can now be serialized without any copy using out-of-band buffers,
and with one less copy using in-band buffers. This results, for large arrays,
in an up to 66% drop in peak memory usage.

build shell independence
------------------------
NumPy builds should no longer interact with the host machine
shell directly. ``exec_command`` has been replaced with
``subprocess.check_output`` where appropriate.


`np.polynomial.Polynomial` classes render in LaTeX in Jupyter notebooks
-----------------------------------------------------------------------

When used in a front-end that supports it, `Polynomial` instances are now
rendered through LaTeX. The current format is experimental, and is subject to
change.

``randint`` and ``choice`` now work on empty distributions
----------------------------------------------------------
Even when no elements needed to be drawn, ``np.random.randint`` and
``np.random.choice`` raised an error when the arguments described an empty
distribution. This has been fixed so that e.g.
``np.random.choice([], 0) == np.array([], dtype=float64)``.

``linalg.lstsq`` and ``linalg.qr`` now work with empty matrices
---------------------------------------------------------------
Previously, a ``LinAlgError`` would be raised when an empty matrix/empty
matrices (with zero rows and/or columns) is/are passed in. Now outputs of
appropriate shapes are returned.

``np.diff`` Added kwargs prepend and append
-------------------------------------------
Add kwargs prepend and append, allowing for values to be inserted
on either end of the differences.  Similar to options for ediff1d.
Allows for the inverse of cumsum easily via prepend=0

ARM support updated
-------------------
Support for ARM CPUs has been updated to accommodate 32 and 64 bit targets,
and also big and little endian byte ordering. AARCH32 memory alignment issues
have been addressed.

Appending to build flags
------------------------
`numpy.distutils` has always overridden rather than appended to `LDFLAGS` and
other similar such environment variables for compiling Fortran extensions.
Now, if the `NPY_DISTUTILS_APPEND_FLAGS` environment variable is set to 1, the
behavior will be appending.  This applied to: `LDFLAGS`, `F77FLAGS`,
`F90FLAGS`, `FREEFLAGS`, `FOPT`, `FDEBUG`, and `FFLAGS`.  See gh-11525 for more
details.

Generalized ufunc signatures now allow fixed-size dimensions
------------------------------------------------------------
By using a numerical value in the signature of a generalized ufunc, one can
indicate that the given function requires input or output to have dimensions
with the given size. E.g., the signature of a function that converts a polar
angle to a two-dimensional cartesian unit vector would be ``()->(2)``; that
for one that converts two spherical angles to a three-dimensional unit vector
would be ``(),()->(3)``; and that for the cross product of two
three-dimensional vectors would be ``(3),(3)->(3)``.

Note that to the elementary function these dimensions are not treated any
differently from variable ones indicated with a name starting with a letter;
the loop still is passed the corresponding size, but it can now count on that
size being equal to the fixed one given in the signature.

Generalized ufunc signatures now allow flexible dimensions
----------------------------------------------------------

Some functions, in particular numpy's implementation of ` as ``matmul``,
are very similar to generalized ufuncs in that they operate over core
dimensions, but one could not present them as such because they were able to
deal with inputs in which a dimension is missing. To support this, it is now
allowed to postfix a dimension name with a question mark to indicate that the
dimension does not necessarily have to be present.

With this addition, the signature for ``matmul`` can be expressed as
``(m?,n),(n,p?)->(m?,p?)``.  This indicates that if, e.g., the second operand
has only one dimension, for the purposes of the elementary function it will be
treated as if that input has core shape ``(n, 1)``, and the output has the
corresponding core shape of ``(m, 1)``. The actual output array, however, has
the flexible dimension removed, i.e., it will have shape ``(..., m)``.
Similarly, if both arguments have only a single dimension, the inputs will be
presented as having shapes ``(1, n)`` and ``(n, 1)`` to the elementary
function, and the output as ``(1, 1)``, while the actual output array returned
will have shape ``()``. In this way, the signature allows one to use a
single elementary function for four related but different signatures,
``(m,n),(n,p)->(m,p)``, ``(n),(n,p)->(p)``, ``(m,n),(n)->(m)`` and
``(n),(n)->()``.

``np.clip`` and the ``clip`` method check for memory overlap
------------------------------------------------------------
The ``out`` argument to these functions is now always tested for memory overlap
to avoid corrupted results when memory overlap occurs.

New value ``unscaled`` for option ``cov`` in ``np.polyfit''
-----------------------------------------------------------
A further possible value has been added to the ``cov`` parameter of the
``np.polyfit`` function. With ``cov='unscaled'`` the scaling of the covariance
matrix is disabled completely (similar to setting ``absolute_sigma=True'' in
``scipy.optimize.curve_fit``). This would be useful in occasions, where the
weights are given by 1/sigma with sigma being the (known) standard errors of
(Gaussian distributed) data points, in which case the unscaled matrix is
already a correct estimate for the covariance matrix.

Detailed docstrings for scalar numeric types
--------------------------------------------
The ``help`` function, when applied to numeric types such as `np.intc`,
`np.int_`, and `np.longlong`, now lists all of the aliased names for that type,
distinguishing between platform -dependent and -independent aliases.

``__module__`` attribute now points to public modules
-----------------------------------------------------
The ``__module__`` attribute on most NumPy functions has been updated to refer
to the preferred public module from which to access a function, rather than
the module in which the function happens to be defined. This produces more
informative displays for functions in tools such as IPython, e.g., instead of
``<function 'numpy.core.fromnumeric.sum'>`` you now see
``<function 'numpy.sum'>``.

Large allocations marked as suitable for transparent hugepages
--------------------------------------------------------------
On systems that support transparent hugepages over the madvise system call
numpy now marks that large memory allocations can be backed by hugepages which
reduces page fault overhead and can in some fault heavy cases improve
performance significantly.
On Linux for huge pages to be used the setting
`/sys/kernel/mm/transparent_hugepage/enabled` must be at least `madvise`.
Systems which already have it set to `always` will not see much difference as
the kernel will automatically use huge pages where appropriate.

Users of very old Linux kernels (~3.x and older) should make sure that
`/sys/kernel/mm/transparent_hugepage/defrag` is not set to `always` to avoid
performance problems due concurrency issues in the memory defragmentation.

Alpine Linux (and other musl c library distros) support
-------------------------------------------------------
We now default to use `fenv.h` for floating point status error reporting.
Previously we had a broken default that sometimes would not report underflow,
overflow, and invalid floating point operations. Now we can support non-glibc
distrubutions like Alpine Linux as long as they ship `fenv.h`.

Speedup ``np.block`` for large arrays
-------------------------------------
Large arrays (greater than ``512 * 512``) now use a blocking algorithm based on
copying the data directly into the appropriate slice of the resulting array.
This results in significant speedups for these large arrays, particularly for
arrays being blocked along more than 2 dimensions.

``arr.ctypes.data_as(...)`` holds a reference to arr
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Previously the caller was responsible for keeping the array alive for the
lifetime of the pointer.

Speedup ``np.take`` for read-only arrays
----------------------------------------
The implementation of ``np.take`` no longer makes an unnecessary copy of the
source array when its ``writeable`` flag is set to ``False``.

Support path-like objects for more functions
--------------------------------------------
The ``np.core.records.fromfile`` function now supports ``pathlib.Path``
and other path-like objects in addition to a file object. Furthermore, the
``np.load`` function now also supports path-like objects when
using memory mapping (``mmap_mode`` keyword argument).

Better behaviour of ufunc identities during reductions
------------------------------------------------------
Universal functions have an ``.identity`` which is used when ``.reduce`` is
called on an empty axis.

As of this release, the logical binary ufuncs, `logical_and`, `logical_or`,
and `logical_xor`, now have ``identity``s of type `bool`, where previously they
were of type `int`. This restores the 1.14 behavior of getting ``bool``s when
reducing empty object arrays with these ufuncs, while also keeping the 1.15
behavior of getting ``int``s when reducing empty object arrays with arithmetic
ufuncs like ``add`` and ``multiply``.

Additionally, `logaddexp` now has an identity of ``-inf``, allowing it to be
called on empty sequences, where previously it could not be.

This is possible thanks to the new
:c:function:`PyUFunc_FromFuncAndDataAndSignatureAndIdentity`, which allows
arbitrary values to be used as identities now.

Improved conversion from ctypes objects
---------------------------------------
Numpy has always supported taking a value or type from ``ctypes`` and
converting it into an array or dtype, but only behaved correctly for simpler
types. As of this release, this caveat is lifted - now:

* The ``_pack_`` attribute of ``ctypes.Structure``, used to emulate C's
``__attribute__((packed))``, is respected.
* Endianness of all ctypes objects is preserved
* ``ctypes.Union`` is supported
* Unrepresentable constructs raise exceptions, rather than producing
dangerously incorrect results:
* Bitfields are no longer interpreted as sub-arrays
* Pointers are no longer replaced with the type that they point to

A new ``ndpointer.contents`` member
-----------------------------------
This matches the ``.contents`` member of normal ctypes arrays, and can be used
to construct an ``np.array`` around the pointers contents.

This replaces ``np.array(some_nd_pointer)``, which stopped working in 1.15.

As a side effect of this change, ``ndpointer`` now supports dtypes with
overlapping fields and padding.

``matmul`` is now a ``ufunc``
-----------------------------
`numpy.matmul` is now a ufunc which means that both the function and the
``__matmul__`` operator can now be overridden by ``__array_ufunc__``. Its
implementation has also changed, ensuring it uses the same BLAS routines as
`numpy.dot`, ensuring its performance is similar for large matrices.

Start and stop arrays for ``linspace``, ``logspace`` and ``geomspace``
----------------------------------------------------------------------
These functions used to be limited to scalar stop and start values, but can
now take arrays, which will be properly broadcast and result in an output
which has one axis prepended.  This can be used, e.g., to obtain linearly
interpolated points between sets of points.

Changes
=======

Comparison ufuncs will now error rather than return NotImplemented
------------------------------------------------------------------
Previously, comparison ufuncs such as ``np.equal`` would return
`NotImplemented` if their arguments had structured dtypes, to help comparison
operators such as ``__eq__`` deal with those.  This is no longer needed, as the
relevant logic has moved to the comparison operators proper (which thus do
continue to return `NotImplemented` as needed). Hence, like all other ufuncs,
the comparison ufuncs will now error on structured dtypes.

Positive will now raise a deprecation warning for non-numerical arrays
----------------------------------------------------------------------
Previously, ``+array`` unconditionally returned a copy. Now, it will
raise a ``DeprecationWarning`` if the array is not numerical (i.e.,
if ``np.positive(array)`` raises a ``TypeError``. For ``ndarray``
subclasses that override the default ``__array_ufunc__`` implementation,
the ``TypeError`` is passed on.

``NDArrayOperatorsMixin`` now implements matrix multiplication
--------------------------------------------------------------
Previously, ``np.lib.mixins.NDArrayOperatorsMixin`` did not implement the
special methods for Python's matrix multiplication operator (`). This has
changed now that ``matmul`` is a ufunc and can be overriden using
``__array_ufunc__``.

The scaling of the covariance matrix in ``np.polyfit`` is different
-------------------------------------------------------------------
So far, ``np.polyfit`` used a non-standard factor in the scaling of the the
covariance matrix. Namely, rather than using the standard chisq/(M-N), it
scales it with chisq/(M-N-2) where M is the number of data points and N is the
number of parameters.  This scaling is inconsistent with other fitting programs
such as e.g. ``scipy.optimize.curve_fit`` and was changed to chisq/(M-N).

``maximum`` and ``minimum`` no longer emit warnings
---------------------------------------------------
As part of code introduced in 1.10,  ``float32`` and ``float64`` set invalid
float status when a Nan is encountered in `numpy.maximum` and `numpy.minimum`,
when using SSE2 semantics. This caused a `RuntimeWarning` to sometimes be
emitted. In 1.15 we fixed the inconsistencies which caused the warnings to
become more conspicuous. Now no warnings will be emitted.

Umath and multiarray c-extension modules merged into a single module
--------------------------------------------------------------------
The two modules were merged, according to the first step in `NEP 15`_.
Previously `np.core.umath` and `np.core.multiarray` were the c-extension
modules, they are now python wrappers to the single `np.core/_multiarray_math`
c-extension module.

.. _`NEP 15` : http://www.numpy.org/neps/nep-0015-merge-multiarray-umath.html

``getfield`` validity checks extended
----------------------------------------
`numpy.ndarray.getfield` now checks the dtype and offset arguments to prevent
accessing invalid memory locations.

NumPy functions now support overrides with ``__array_function__``
-----------------------------------------------------------------
It is now possible to override the implementation of almost all NumPy functions
on non-NumPy arrays by defining a ``__array_function__`` method, as described
in `NEP 18`_. The sole exception are functions for explicitly casting to NumPy
arrays such as ``np.array``. As noted in the NEP, this feature remains
experimental and the details of how to implement such overrides may change in
the future.

.. _`NEP 15` : http://www.numpy.org/neps/nep-0015-merge-multiarray-umath.html
.. _`NEP 18` : http://www.numpy.org/neps/nep-0018-array-function-protocol.html
Arrays based off readonly buffers cannot be set ``writeable``
-------------------------------------------------------------
We now disallow setting the ``writeable`` flag True on arrays created
from ``fromstring(readonly-buffer)``.


=========================

Links

• PyPI: https://pypi.org/project/numpy
• Changelog: https://pyup.io/changelogs/numpy/
• Homepage: https://www.numpy.org

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