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@@ -382,3 +382,6 @@ tuning-competition-baseline/.venv/lib/python3.11/site-packages/nvidia/cudnn/lib/
 .venv/lib/python3.11/site-packages/numpy/core/tests/__pycache__/test_ufunc.cpython-311.pyc filter=lfs diff=lfs merge=lfs -text
 .venv/lib/python3.11/site-packages/numpy/core/tests/__pycache__/test_nditer.cpython-311.pyc filter=lfs diff=lfs merge=lfs -text
 .venv/lib/python3.11/site-packages/numpy/core/tests/__pycache__/test_numeric.cpython-311.pyc filter=lfs diff=lfs merge=lfs -text
+.venv/lib/python3.11/site-packages/numpy/distutils/__pycache__/misc_util.cpython-311.pyc filter=lfs diff=lfs merge=lfs -text
+.venv/lib/python3.11/site-packages/numpy/distutils/__pycache__/ccompiler_opt.cpython-311.pyc filter=lfs diff=lfs merge=lfs -text
+.venv/lib/python3.11/site-packages/numpy/distutils/__pycache__/system_info.cpython-311.pyc filter=lfs diff=lfs merge=lfs -text

.venv/lib/python3.11/site-packages/numpy/_core/__init__.py

@@ -0,0 +1,4 @@
+"""
+This private module only contains stubs for interoperability with
+NumPy 2.0 pickled arrays. It may not be used by the end user.
+"""

.venv/lib/python3.11/site-packages/numpy/_core/_dtype.py

@@ -0,0 +1,6 @@
+from numpy.core import _dtype
+
+_globals = globals()
+
+for item in _dtype.__dir__():
+    _globals[item] = getattr(_dtype, item)

.venv/lib/python3.11/site-packages/numpy/_core/_dtype_ctypes.py

@@ -0,0 +1,6 @@
+from numpy.core import _dtype_ctypes
+
+_globals = globals()
+
+for item in _dtype_ctypes.__dir__():
+    _globals[item] = getattr(_dtype_ctypes, item)

.venv/lib/python3.11/site-packages/numpy/_core/_internal.py

@@ -0,0 +1,6 @@
+from numpy.core import _internal
+
+_globals = globals()
+
+for item in _internal.__dir__():
+    _globals[item] = getattr(_internal, item)

.venv/lib/python3.11/site-packages/numpy/_core/_multiarray_umath.py

@@ -0,0 +1,6 @@
+from numpy.core import _multiarray_umath
+
+_globals = globals()
+
+for item in _multiarray_umath.__dir__():
+    _globals[item] = getattr(_multiarray_umath, item)

.venv/lib/python3.11/site-packages/numpy/_core/multiarray.py

@@ -0,0 +1,6 @@
+from numpy.core import multiarray
+
+_globals = globals()
+
+for item in multiarray.__dir__():
+    _globals[item] = getattr(multiarray, item)

.venv/lib/python3.11/site-packages/numpy/_core/umath.py

@@ -0,0 +1,6 @@
+from numpy.core import umath
+
+_globals = globals()
+
+for item in umath.__dir__():
+    _globals[item] = getattr(umath, item)

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.venv/lib/python3.11/site-packages/numpy/ma/API_CHANGES.txt

@@ -0,0 +1,135 @@
+.. -*- rest -*-
+
+==================================================
+API changes in the new masked array implementation
+==================================================
+
+Masked arrays are subclasses of ndarray
+---------------------------------------
+
+Contrary to the original implementation, masked arrays are now regular
+ndarrays::
+
+  >>> x = masked_array([1,2,3],mask=[0,0,1])
+  >>> print isinstance(x, numpy.ndarray)
+  True
+
+
+``_data`` returns a view of the masked array
+--------------------------------------------
+
+Masked arrays are composed of a ``_data`` part and a ``_mask``. Accessing the
+``_data`` part will return a regular ndarray or any of its subclass, depending
+on the initial data::
+
+  >>> x = masked_array(numpy.matrix([[1,2],[3,4]]),mask=[[0,0],[0,1]])
+  >>> print x._data
+  [[1 2]
+   [3 4]]
+  >>> print type(x._data)
+  <class 'numpy.matrixlib.defmatrix.matrix'>
+
+
+In practice, ``_data`` is implemented as a property, not as an attribute.
+Therefore, you cannot access it directly, and some simple tests such as the
+following one will fail::
+
+  >>>x._data is x._data
+  False
+
+
+``filled(x)`` can return a subclass of ndarray
+----------------------------------------------
+The function ``filled(a)`` returns an array of the same type as ``a._data``::
+
+  >>> x = masked_array(numpy.matrix([[1,2],[3,4]]),mask=[[0,0],[0,1]])
+  >>> y = filled(x)
+  >>> print type(y)
+  <class 'numpy.matrixlib.defmatrix.matrix'>
+  >>> print y
+  matrix([[     1,      2],
+          [     3, 999999]])
+
+
+``put``, ``putmask`` behave like their ndarray counterparts
+-----------------------------------------------------------
+
+Previously, ``putmask`` was used like this::
+
+  mask = [False,True,True]
+  x = array([1,4,7],mask=mask)
+  putmask(x,mask,[3])
+
+which translated to::
+
+  x[~mask] = [3]
+
+(Note that a ``True``-value in a mask suppresses a value.)
+
+In other words, the mask had the same length as ``x``, whereas
+``values`` had ``sum(~mask)`` elements.
+
+Now, the behaviour is similar to that of ``ndarray.putmask``, where
+the mask and the values are both the same length as ``x``, i.e.
+
+::
+
+  putmask(x,mask,[3,0,0])
+
+
+``fill_value`` is a property
+----------------------------
+
+``fill_value`` is no longer a method, but a property::
+
+  >>> print x.fill_value
+  999999
+
+``cumsum`` and ``cumprod`` ignore missing values
+------------------------------------------------
+
+Missing values are assumed to be the identity element, i.e. 0 for
+``cumsum`` and 1 for ``cumprod``::
+
+  >>> x = N.ma.array([1,2,3,4],mask=[False,True,False,False])
+  >>> print x
+  [1 -- 3 4]
+  >>> print x.cumsum()
+  [1 -- 4 8]
+  >> print x.cumprod()
+  [1 -- 3 12]
+
+``bool(x)`` raises a ValueError
+-------------------------------
+
+Masked arrays now behave like regular ``ndarrays``, in that they cannot be
+converted to booleans:
+
+::
+
+  >>> x = N.ma.array([1,2,3])
+  >>> bool(x)
+  Traceback (most recent call last):
+    File "<stdin>", line 1, in <module>
+  ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()
+
+
+==================================
+New features (non exhaustive list)
+==================================
+
+``mr_``
+-------
+
+``mr_`` mimics the behavior of ``r_`` for masked arrays::
+
+  >>> np.ma.mr_[3,4,5]
+  masked_array(data = [3 4 5],
+        mask = False,
+        fill_value=999999)
+
+
+``anom``
+--------
+
+The ``anom`` method returns the deviations from the average (anomalies).

.venv/lib/python3.11/site-packages/numpy/ma/LICENSE

@@ -0,0 +1,24 @@
+* Copyright (c) 2006, University of Georgia and Pierre G.F. Gerard-Marchant
+* All rights reserved.
+* Redistribution and use in source and binary forms, with or without
+* modification, are permitted provided that the following conditions are met:
+*
+*     * Redistributions of source code must retain the above copyright
+*       notice, this list of conditions and the following disclaimer.
+*     * Redistributions in binary form must reproduce the above copyright
+*       notice, this list of conditions and the following disclaimer in the
+*       documentation and/or other materials provided with the distribution.
+*     * Neither the name of the University of Georgia nor the
+*       names of its contributors may be used to endorse or promote products
+*       derived from this software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
+* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
+* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

.venv/lib/python3.11/site-packages/numpy/ma/README.rst

@@ -0,0 +1,236 @@
+==================================
+A Guide to Masked Arrays in NumPy
+==================================
+
+.. Contents::
+
+See http://www.scipy.org/scipy/numpy/wiki/MaskedArray (dead link)
+for updates of this document.
+
+
+History
+-------
+
+As a regular user of MaskedArray, I (Pierre G.F. Gerard-Marchant) became
+increasingly frustrated with the subclassing of masked arrays (even if
+I can only blame my inexperience). I needed to develop a class of arrays
+that could store some additional information along with numerical values,
+while keeping the possibility for missing data (picture storing a series
+of dates along with measurements, what would later become the `TimeSeries
+Scikit <http://projects.scipy.org/scipy/scikits/wiki/TimeSeries>`__
+(dead link).
+
+I started to implement such a class, but then quickly realized that
+any additional information disappeared when processing these subarrays
+(for example, adding a constant value to a subarray would erase its
+dates). I ended up writing the equivalent of *numpy.core.ma* for my
+particular class, ufuncs included. Everything went fine until I needed to
+subclass my new class, when more problems showed up: some attributes of
+the new subclass were lost during processing. I identified the culprit as
+MaskedArray, which returns masked ndarrays when I expected masked
+arrays of my class. I was preparing myself to rewrite *numpy.core.ma*
+when I forced myself to learn how to subclass ndarrays. As I became more
+familiar with the *__new__* and *__array_finalize__* methods,
+I started to wonder why masked arrays were objects, and not ndarrays,
+and whether it wouldn't be more convenient for subclassing if they did
+behave like regular ndarrays.
+
+The new *maskedarray* is what I eventually come up with. The
+main differences with the initial *numpy.core.ma* package are
+that MaskedArray is now a subclass of *ndarray* and that the
+*_data* section can now be any subclass of *ndarray*. Apart from a
+couple of issues listed below, the behavior of the new MaskedArray
+class reproduces the old one. Initially the *maskedarray*
+implementation was marginally slower than *numpy.ma* in some areas,
+but work is underway to speed it up; the expectation is that it can be
+made substantially faster than the present *numpy.ma*.
+
+
+Note that if the subclass has some special methods and
+attributes, they are not propagated to the masked version:
+this would require a modification of the *__getattribute__*
+method (first trying *ndarray.__getattribute__*, then trying
+*self._data.__getattribute__* if an exception is raised in the first
+place), which really slows things down.
+
+Main differences
+----------------
+
+ * The *_data* part of the masked array can be any subclass of ndarray (but not recarray, cf below).
+ * *fill_value* is now a property, not a function.
+ * in the majority of cases, the mask is forced to *nomask* when no value is actually masked. A notable exception is when a masked array (with no masked values) has just been unpickled.
+ * I got rid of the *share_mask* flag, I never understood its purpose.
+ * *put*, *putmask* and *take* now mimic the ndarray methods, to avoid unpleasant surprises. Moreover, *put* and *putmask* both update the mask when needed.  * if *a* is a masked array, *bool(a)* raises a *ValueError*, as it does with ndarrays.
+ * in the same way, the comparison of two masked arrays is a masked array, not a boolean
+ * *filled(a)* returns an array of the same subclass as *a._data*, and no test is performed on whether it is contiguous or not.
+ * the mask is always printed, even if it's *nomask*, which makes things easy (for me at least) to remember that a masked array is used.
+ * *cumsum* works as if the *_data* array was filled with 0. The mask is preserved, but not updated.
+ * *cumprod* works as if the *_data* array was filled with 1. The mask is preserved, but not updated.
+
+New features
+------------
+
+This list is non-exhaustive...
+
+ * the *mr_* function mimics *r_* for masked arrays.
+ * the *anom* method returns the anomalies (deviations from the average)
+
+Using the new package with numpy.core.ma
+----------------------------------------
+
+I tried to make sure that the new package can understand old masked
+arrays. Unfortunately, there's no upward compatibility.
+
+For example:
+
+>>> import numpy.core.ma as old_ma
+>>> import maskedarray as new_ma
+>>> x = old_ma.array([1,2,3,4,5], mask=[0,0,1,0,0])
+>>> x
+array(data =
+ [     1      2 999999      4      5],
+      mask =
+ [False False True False False],
+      fill_value=999999)
+>>> y = new_ma.array([1,2,3,4,5], mask=[0,0,1,0,0])
+>>> y
+array(data = [1 2 -- 4 5],
+      mask = [False False True False False],
+      fill_value=999999)
+>>> x==y
+array(data =
+ [True True True True True],
+      mask =
+ [False False True False False],
+      fill_value=?)
+>>> old_ma.getmask(x) == new_ma.getmask(x)
+array([True, True, True, True, True])
+>>> old_ma.getmask(y) == new_ma.getmask(y)
+array([True, True, False, True, True])
+>>> old_ma.getmask(y)
+False
+
+
+Using maskedarray with matplotlib
+---------------------------------
+
+Starting with matplotlib 0.91.2, the masked array importing will work with
+the maskedarray branch) as well as with earlier versions.
+
+By default matplotlib still uses numpy.ma, but there is an rcParams setting
+that you can use to select maskedarray instead.  In the matplotlibrc file
+you will find::
+
+  #maskedarray : False       # True to use external maskedarray module
+                             # instead of numpy.ma; this is a temporary #
+                             setting for testing maskedarray.
+
+
+Uncomment and set to True to select maskedarray everywhere.
+Alternatively, you can test a script with maskedarray by using a
+command-line option, e.g.::
+
+  python simple_plot.py --maskedarray
+
+
+Masked records
+--------------
+
+Like *numpy.core.ma*, the *ndarray*-based implementation
+of MaskedArray is limited when working with records: you can
+mask any record of the array, but not a field in a record. If you
+need this feature, you may want to give the *mrecords* package
+a try (available in the *maskedarray* directory in the scipy
+sandbox). This module defines a new class, *MaskedRecord*. An
+instance of this class accepts a *recarray* as data, and uses two
+masks: the *fieldmask* has as many entries as records in the array,
+each entry with the same fields as a record, but of boolean types:
+they indicate whether the field is masked or not; a record entry
+is flagged as masked in the *mask* array if all the fields are
+masked. A few examples in the file should give you an idea of what
+can be done. Note that *mrecords* is still experimental...
+
+Optimizing maskedarray
+----------------------
+
+Should masked arrays be filled before processing or not?
+--------------------------------------------------------
+
+In the current implementation, most operations on masked arrays involve
+the following steps:
+
+ * the input arrays are filled
+ * the operation is performed on the filled arrays
+ * the mask is set for the results, from the combination of the input masks and the mask corresponding to the domain of the operation.
+
+For example, consider the division of two masked arrays::
+
+  import numpy
+  import maskedarray as ma
+  x = ma.array([1,2,3,4],mask=[1,0,0,0], dtype=numpy.float_)
+  y = ma.array([-1,0,1,2], mask=[0,0,0,1], dtype=numpy.float_)
+
+The division of x by y is then computed as::
+
+  d1 = x.filled(0) # d1 = array([0., 2., 3., 4.])
+  d2 = y.filled(1) # array([-1.,  0.,  1.,  1.])
+  m = ma.mask_or(ma.getmask(x), ma.getmask(y)) # m =
+  array([True,False,False,True])
+  dm = ma.divide.domain(d1,d2) # array([False,  True, False, False])
+  result = (d1/d2).view(MaskedArray) # masked_array([-0. inf, 3., 4.])
+  result._mask = logical_or(m, dm)
+
+Note that a division by zero takes place. To avoid it, we can consider
+to fill the input arrays, taking the domain mask into account, so that::
+
+  d1 = x._data.copy() # d1 = array([1., 2., 3., 4.])
+  d2 = y._data.copy() # array([-1.,  0.,  1.,  2.])
+  dm = ma.divide.domain(d1,d2) # array([False,  True, False, False])
+  numpy.putmask(d2, dm, 1) # d2 = array([-1.,  1.,  1.,  2.])
+  m = ma.mask_or(ma.getmask(x), ma.getmask(y)) # m =
+  array([True,False,False,True])
+  result = (d1/d2).view(MaskedArray) # masked_array([-1. 0., 3., 2.])
+  result._mask = logical_or(m, dm)
+
+Note that the *.copy()* is required to avoid updating the inputs with
+*putmask*.  The *.filled()* method also involves a *.copy()*.
+
+A third possibility consists in avoid filling the arrays::
+
+  d1 = x._data # d1 = array([1., 2., 3., 4.])
+  d2 = y._data # array([-1.,  0.,  1.,  2.])
+  dm = ma.divide.domain(d1,d2) # array([False,  True, False, False])
+  m = ma.mask_or(ma.getmask(x), ma.getmask(y)) # m =
+  array([True,False,False,True])
+  result = (d1/d2).view(MaskedArray) # masked_array([-1. inf, 3., 2.])
+  result._mask = logical_or(m, dm)
+
+Note that here again the division by zero takes place.
+
+A quick benchmark gives the following results:
+
+ * *numpy.ma.divide*  : 2.69 ms per loop
+ * classical division     : 2.21 ms per loop
+ * division w/ prefilling : 2.34 ms per loop
+ * division w/o filling   : 1.55 ms per loop
+
+So, is it worth filling the arrays beforehand ? Yes, if we are interested
+in avoiding floating-point exceptions that may fill the result with infs
+and nans. No, if we are only interested into speed...
+
+
+Thanks
+------
+
+I'd like to thank Paul Dubois, Travis Oliphant and Sasha for the
+original masked array package: without you, I would never have started
+that (it might be argued that I shouldn't have anyway, but that's
+another story...).  I also wish to extend these thanks to Reggie Dugard
+and Eric Firing for their suggestions and numerous improvements.
+
+
+Revision notes
+--------------
+
+  * 08/25/2007 : Creation of this page
+  * 01/23/2007 : The package has been moved to the SciPy sandbox, and is regularly updated: please check out your SVN version!

.venv/lib/python3.11/site-packages/numpy/ma/__init__.py

@@ -0,0 +1,54 @@
+"""
+=============
+Masked Arrays
+=============
+
+Arrays sometimes contain invalid or missing data.  When doing operations
+on such arrays, we wish to suppress invalid values, which is the purpose masked
+arrays fulfill (an example of typical use is given below).
+
+For example, examine the following array:
+
+>>> x = np.array([2, 1, 3, np.nan, 5, 2, 3, np.nan])
+
+When we try to calculate the mean of the data, the result is undetermined:
+
+>>> np.mean(x)
+nan
+
+The mean is calculated using roughly ``np.sum(x)/len(x)``, but since
+any number added to ``NaN`` [1]_ produces ``NaN``, this doesn't work.  Enter
+masked arrays:
+
+>>> m = np.ma.masked_array(x, np.isnan(x))
+>>> m
+masked_array(data = [2.0 1.0 3.0 -- 5.0 2.0 3.0 --],
+      mask = [False False False  True False False False  True],
+      fill_value=1e+20)
+
+Here, we construct a masked array that suppress all ``NaN`` values.  We
+may now proceed to calculate the mean of the other values:
+
+>>> np.mean(m)
+2.6666666666666665
+
+.. [1] Not-a-Number, a floating point value that is the result of an
+       invalid operation.
+
+.. moduleauthor:: Pierre Gerard-Marchant
+.. moduleauthor:: Jarrod Millman
+
+"""
+from . import core
+from .core import *
+
+from . import extras
+from .extras import *
+
+__all__ = ['core', 'extras']
+__all__ += core.__all__
+__all__ += extras.__all__
+
+from numpy._pytesttester import PytestTester
+test = PytestTester(__name__)
+del PytestTester

.venv/lib/python3.11/site-packages/numpy/ma/__init__.pyi

@@ -0,0 +1,234 @@
+from numpy._pytesttester import PytestTester
+
+from numpy.ma import extras as extras
+
+from numpy.ma.core import (
+    MAError as MAError,
+    MaskError as MaskError,
+    MaskType as MaskType,
+    MaskedArray as MaskedArray,
+    abs as abs,
+    absolute as absolute,
+    add as add,
+    all as all,
+    allclose as allclose,
+    allequal as allequal,
+    alltrue as alltrue,
+    amax as amax,
+    amin as amin,
+    angle as angle,
+    anom as anom,
+    anomalies as anomalies,
+    any as any,
+    append as append,
+    arange as arange,
+    arccos as arccos,
+    arccosh as arccosh,
+    arcsin as arcsin,
+    arcsinh as arcsinh,
+    arctan as arctan,
+    arctan2 as arctan2,
+    arctanh as arctanh,
+    argmax as argmax,
+    argmin as argmin,
+    argsort as argsort,
+    around as around,
+    array as array,
+    asanyarray as asanyarray,
+    asarray as asarray,
+    bitwise_and as bitwise_and,
+    bitwise_or as bitwise_or,
+    bitwise_xor as bitwise_xor,
+    bool_ as bool_,
+    ceil as ceil,
+    choose as choose,
+    clip as clip,
+    common_fill_value as common_fill_value,
+    compress as compress,
+    compressed as compressed,
+    concatenate as concatenate,
+    conjugate as conjugate,
+    convolve as convolve,
+    copy as copy,
+    correlate as correlate,
+    cos as cos,
+    cosh as cosh,
+    count as count,
+    cumprod as cumprod,
+    cumsum as cumsum,
+    default_fill_value as default_fill_value,
+    diag as diag,
+    diagonal as diagonal,
+    diff as diff,
+    divide as divide,
+    empty as empty,
+    empty_like as empty_like,
+    equal as equal,
+    exp as exp,
+    expand_dims as expand_dims,
+    fabs as fabs,
+    filled as filled,
+    fix_invalid as fix_invalid,
+    flatten_mask as flatten_mask,
+    flatten_structured_array as flatten_structured_array,
+    floor as floor,
+    floor_divide as floor_divide,
+    fmod as fmod,
+    frombuffer as frombuffer,
+    fromflex as fromflex,
+    fromfunction as fromfunction,
+    getdata as getdata,
+    getmask as getmask,
+    getmaskarray as getmaskarray,
+    greater as greater,
+    greater_equal as greater_equal,
+    harden_mask as harden_mask,
+    hypot as hypot,
+    identity as identity,
+    ids as ids,
+    indices as indices,
+    inner as inner,
+    innerproduct as innerproduct,
+    isMA as isMA,
+    isMaskedArray as isMaskedArray,
+    is_mask as is_mask,
+    is_masked as is_masked,
+    isarray as isarray,
+    left_shift as left_shift,
+    less as less,
+    less_equal as less_equal,
+    log as log,
+    log10 as log10,
+    log2 as log2,
+    logical_and as logical_and,
+    logical_not as logical_not,
+    logical_or as logical_or,
+    logical_xor as logical_xor,
+    make_mask as make_mask,
+    make_mask_descr as make_mask_descr,
+    make_mask_none as make_mask_none,
+    mask_or as mask_or,
+    masked as masked,
+    masked_array as masked_array,
+    masked_equal as masked_equal,
+    masked_greater as masked_greater,
+    masked_greater_equal as masked_greater_equal,
+    masked_inside as masked_inside,
+    masked_invalid as masked_invalid,
+    masked_less as masked_less,
+    masked_less_equal as masked_less_equal,
+    masked_not_equal as masked_not_equal,
+    masked_object as masked_object,
+    masked_outside as masked_outside,
+    masked_print_option as masked_print_option,
+    masked_singleton as masked_singleton,
+    masked_values as masked_values,
+    masked_where as masked_where,
+    max as max,
+    maximum as maximum,
+    maximum_fill_value as maximum_fill_value,
+    mean as mean,
+    min as min,
+    minimum as minimum,
+    minimum_fill_value as minimum_fill_value,
+    mod as mod,
+    multiply as multiply,
+    mvoid as mvoid,
+    ndim as ndim,
+    negative as negative,
+    nomask as nomask,
+    nonzero as nonzero,
+    not_equal as not_equal,
+    ones as ones,
+    outer as outer,
+    outerproduct as outerproduct,
+    power as power,
+    prod as prod,
+    product as product,
+    ptp as ptp,
+    put as put,
+    putmask as putmask,
+    ravel as ravel,
+    remainder as remainder,
+    repeat as repeat,
+    reshape as reshape,
+    resize as resize,
+    right_shift as right_shift,
+    round as round,
+    set_fill_value as set_fill_value,
+    shape as shape,
+    sin as sin,
+    sinh as sinh,
+    size as size,
+    soften_mask as soften_mask,
+    sometrue as sometrue,
+    sort as sort,
+    sqrt as sqrt,
+    squeeze as squeeze,
+    std as std,
+    subtract as subtract,
+    sum as sum,
+    swapaxes as swapaxes,
+    take as take,
+    tan as tan,
+    tanh as tanh,
+    trace as trace,
+    transpose as transpose,
+    true_divide as true_divide,
+    var as var,
+    where as where,
+    zeros as zeros,
+)
+
+from numpy.ma.extras import (
+    apply_along_axis as apply_along_axis,
+    apply_over_axes as apply_over_axes,
+    atleast_1d as atleast_1d,
+    atleast_2d as atleast_2d,
+    atleast_3d as atleast_3d,
+    average as average,
+    clump_masked as clump_masked,
+    clump_unmasked as clump_unmasked,
+    column_stack as column_stack,
+    compress_cols as compress_cols,
+    compress_nd as compress_nd,
+    compress_rowcols as compress_rowcols,
+    compress_rows as compress_rows,
+    count_masked as count_masked,
+    corrcoef as corrcoef,
+    cov as cov,
+    diagflat as diagflat,
+    dot as dot,
+    dstack as dstack,
+    ediff1d as ediff1d,
+    flatnotmasked_contiguous as flatnotmasked_contiguous,
+    flatnotmasked_edges as flatnotmasked_edges,
+    hsplit as hsplit,
+    hstack as hstack,
+    isin as isin,
+    in1d as in1d,
+    intersect1d as intersect1d,
+    mask_cols as mask_cols,
+    mask_rowcols as mask_rowcols,
+    mask_rows as mask_rows,
+    masked_all as masked_all,
+    masked_all_like as masked_all_like,
+    median as median,
+    mr_ as mr_,
+    ndenumerate as ndenumerate,
+    notmasked_contiguous as notmasked_contiguous,
+    notmasked_edges as notmasked_edges,
+    polyfit as polyfit,
+    row_stack as row_stack,
+    setdiff1d as setdiff1d,
+    setxor1d as setxor1d,
+    stack as stack,
+    unique as unique,
+    union1d as union1d,
+    vander as vander,
+    vstack as vstack,
+)
+
+__all__: list[str]
+__path__: list[str]
+test: PytestTester

.venv/lib/python3.11/site-packages/numpy/ma/core.pyi

@@ -0,0 +1,471 @@
+from collections.abc import Callable
+from typing import Any, TypeVar
+from numpy import ndarray, dtype, float64
+
+from numpy import (
+    amax as amax,
+    amin as amin,
+    bool_ as bool_,
+    expand_dims as expand_dims,
+    clip as clip,
+    indices as indices,
+    ones_like as ones_like,
+    squeeze as squeeze,
+    zeros_like as zeros_like,
+)
+
+from numpy.lib.function_base import (
+    angle as angle,
+)
+
+# TODO: Set the `bound` to something more suitable once we
+# have proper shape support
+_ShapeType = TypeVar("_ShapeType", bound=Any)
+_DType_co = TypeVar("_DType_co", bound=dtype[Any], covariant=True)
+
+__all__: list[str]
+
+MaskType = bool_
+nomask: bool_
+
+class MaskedArrayFutureWarning(FutureWarning): ...
+class MAError(Exception): ...
+class MaskError(MAError): ...
+
+def default_fill_value(obj): ...
+def minimum_fill_value(obj): ...
+def maximum_fill_value(obj): ...
+def set_fill_value(a, fill_value): ...
+def common_fill_value(a, b): ...
+def filled(a, fill_value=...): ...
+def getdata(a, subok=...): ...
+get_data = getdata
+
+def fix_invalid(a, mask=..., copy=..., fill_value=...): ...
+
+class _MaskedUFunc:
+    f: Any
+    __doc__: Any
+    __name__: Any
+    def __init__(self, ufunc): ...
+
+class _MaskedUnaryOperation(_MaskedUFunc):
+    fill: Any
+    domain: Any
+    def __init__(self, mufunc, fill=..., domain=...): ...
+    def __call__(self, a, *args, **kwargs): ...
+
+class _MaskedBinaryOperation(_MaskedUFunc):
+    fillx: Any
+    filly: Any
+    def __init__(self, mbfunc, fillx=..., filly=...): ...
+    def __call__(self, a, b, *args, **kwargs): ...
+    def reduce(self, target, axis=..., dtype=...): ...
+    def outer(self, a, b): ...
+    def accumulate(self, target, axis=...): ...
+
+class _DomainedBinaryOperation(_MaskedUFunc):
+    domain: Any
+    fillx: Any
+    filly: Any
+    def __init__(self, dbfunc, domain, fillx=..., filly=...): ...
+    def __call__(self, a, b, *args, **kwargs): ...
+
+exp: _MaskedUnaryOperation
+conjugate: _MaskedUnaryOperation
+sin: _MaskedUnaryOperation
+cos: _MaskedUnaryOperation
+arctan: _MaskedUnaryOperation
+arcsinh: _MaskedUnaryOperation
+sinh: _MaskedUnaryOperation
+cosh: _MaskedUnaryOperation
+tanh: _MaskedUnaryOperation
+abs: _MaskedUnaryOperation
+absolute: _MaskedUnaryOperation
+fabs: _MaskedUnaryOperation
+negative: _MaskedUnaryOperation
+floor: _MaskedUnaryOperation
+ceil: _MaskedUnaryOperation
+around: _MaskedUnaryOperation
+logical_not: _MaskedUnaryOperation
+sqrt: _MaskedUnaryOperation
+log: _MaskedUnaryOperation
+log2: _MaskedUnaryOperation
+log10: _MaskedUnaryOperation
+tan: _MaskedUnaryOperation
+arcsin: _MaskedUnaryOperation
+arccos: _MaskedUnaryOperation
+arccosh: _MaskedUnaryOperation
+arctanh: _MaskedUnaryOperation
+
+add: _MaskedBinaryOperation
+subtract: _MaskedBinaryOperation
+multiply: _MaskedBinaryOperation
+arctan2: _MaskedBinaryOperation
+equal: _MaskedBinaryOperation
+not_equal: _MaskedBinaryOperation
+less_equal: _MaskedBinaryOperation
+greater_equal: _MaskedBinaryOperation
+less: _MaskedBinaryOperation
+greater: _MaskedBinaryOperation
+logical_and: _MaskedBinaryOperation
+alltrue: _MaskedBinaryOperation
+logical_or: _MaskedBinaryOperation
+sometrue: Callable[..., Any]
+logical_xor: _MaskedBinaryOperation
+bitwise_and: _MaskedBinaryOperation
+bitwise_or: _MaskedBinaryOperation
+bitwise_xor: _MaskedBinaryOperation
+hypot: _MaskedBinaryOperation
+divide: _MaskedBinaryOperation
+true_divide: _MaskedBinaryOperation
+floor_divide: _MaskedBinaryOperation
+remainder: _MaskedBinaryOperation
+fmod: _MaskedBinaryOperation
+mod: _MaskedBinaryOperation
+
+def make_mask_descr(ndtype): ...
+def getmask(a): ...
+get_mask = getmask
+
+def getmaskarray(arr): ...
+def is_mask(m): ...
+def make_mask(m, copy=..., shrink=..., dtype=...): ...
+def make_mask_none(newshape, dtype=...): ...
+def mask_or(m1, m2, copy=..., shrink=...): ...
+def flatten_mask(mask): ...
+def masked_where(condition, a, copy=...): ...
+def masked_greater(x, value, copy=...): ...
+def masked_greater_equal(x, value, copy=...): ...
+def masked_less(x, value, copy=...): ...
+def masked_less_equal(x, value, copy=...): ...
+def masked_not_equal(x, value, copy=...): ...
+def masked_equal(x, value, copy=...): ...
+def masked_inside(x, v1, v2, copy=...): ...
+def masked_outside(x, v1, v2, copy=...): ...
+def masked_object(x, value, copy=..., shrink=...): ...
+def masked_values(x, value, rtol=..., atol=..., copy=..., shrink=...): ...
+def masked_invalid(a, copy=...): ...
+
+class _MaskedPrintOption:
+    def __init__(self, display): ...
+    def display(self): ...
+    def set_display(self, s): ...
+    def enabled(self): ...
+    def enable(self, shrink=...): ...
+
+masked_print_option: _MaskedPrintOption
+
+def flatten_structured_array(a): ...
+
+class MaskedIterator:
+    ma: Any
+    dataiter: Any
+    maskiter: Any
+    def __init__(self, ma): ...
+    def __iter__(self): ...
+    def __getitem__(self, indx): ...
+    def __setitem__(self, index, value): ...
+    def __next__(self): ...
+
+class MaskedArray(ndarray[_ShapeType, _DType_co]):
+    __array_priority__: Any
+    def __new__(cls, data=..., mask=..., dtype=..., copy=..., subok=..., ndmin=..., fill_value=..., keep_mask=..., hard_mask=..., shrink=..., order=...): ...
+    def __array_finalize__(self, obj): ...
+    def __array_wrap__(self, obj, context=...): ...
+    def view(self, dtype=..., type=..., fill_value=...): ...
+    def __getitem__(self, indx): ...
+    def __setitem__(self, indx, value): ...
+    @property
+    def dtype(self): ...
+    @dtype.setter
+    def dtype(self, dtype): ...
+    @property
+    def shape(self): ...
+    @shape.setter
+    def shape(self, shape): ...
+    def __setmask__(self, mask, copy=...): ...
+    @property
+    def mask(self): ...
+    @mask.setter
+    def mask(self, value): ...
+    @property
+    def recordmask(self): ...
+    @recordmask.setter
+    def recordmask(self, mask): ...
+    def harden_mask(self): ...
+    def soften_mask(self): ...
+    @property
+    def hardmask(self): ...
+    def unshare_mask(self): ...
+    @property
+    def sharedmask(self): ...
+    def shrink_mask(self): ...
+    @property
+    def baseclass(self): ...
+    data: Any
+    @property
+    def flat(self): ...
+    @flat.setter
+    def flat(self, value): ...
+    @property
+    def fill_value(self): ...
+    @fill_value.setter
+    def fill_value(self, value=...): ...
+    get_fill_value: Any
+    set_fill_value: Any
+    def filled(self, fill_value=...): ...
+    def compressed(self): ...
+    def compress(self, condition, axis=..., out=...): ...
+    def __eq__(self, other): ...
+    def __ne__(self, other): ...
+    def __ge__(self, other): ...
+    def __gt__(self, other): ...
+    def __le__(self, other): ...
+    def __lt__(self, other): ...
+    def __add__(self, other): ...
+    def __radd__(self, other): ...
+    def __sub__(self, other): ...
+    def __rsub__(self, other): ...
+    def __mul__(self, other): ...
+    def __rmul__(self, other): ...
+    def __div__(self, other): ...
+    def __truediv__(self, other): ...
+    def __rtruediv__(self, other): ...
+    def __floordiv__(self, other): ...
+    def __rfloordiv__(self, other): ...
+    def __pow__(self, other): ...
+    def __rpow__(self, other): ...
+    def __iadd__(self, other): ...
+    def __isub__(self, other): ...
+    def __imul__(self, other): ...
+    def __idiv__(self, other): ...
+    def __ifloordiv__(self, other): ...
+    def __itruediv__(self, other): ...
+    def __ipow__(self, other): ...
+    def __float__(self): ...
+    def __int__(self): ...
+    @property  # type: ignore[misc]
+    def imag(self): ...
+    get_imag: Any
+    @property  # type: ignore[misc]
+    def real(self): ...
+    get_real: Any
+    def count(self, axis=..., keepdims=...): ...
+    def ravel(self, order=...): ...
+    def reshape(self, *s, **kwargs): ...
+    def resize(self, newshape, refcheck=..., order=...): ...
+    def put(self, indices, values, mode=...): ...
+    def ids(self): ...
+    def iscontiguous(self): ...
+    def all(self, axis=..., out=..., keepdims=...): ...
+    def any(self, axis=..., out=..., keepdims=...): ...
+    def nonzero(self): ...
+    def trace(self, offset=..., axis1=..., axis2=..., dtype=..., out=...): ...
+    def dot(self, b, out=..., strict=...): ...
+    def sum(self, axis=..., dtype=..., out=..., keepdims=...): ...
+    def cumsum(self, axis=..., dtype=..., out=...): ...
+    def prod(self, axis=..., dtype=..., out=..., keepdims=...): ...
+    product: Any
+    def cumprod(self, axis=..., dtype=..., out=...): ...
+    def mean(self, axis=..., dtype=..., out=..., keepdims=...): ...
+    def anom(self, axis=..., dtype=...): ...
+    def var(self, axis=..., dtype=..., out=..., ddof=..., keepdims=...): ...
+    def std(self, axis=..., dtype=..., out=..., ddof=..., keepdims=...): ...
+    def round(self, decimals=..., out=...): ...
+    def argsort(self, axis=..., kind=..., order=..., endwith=..., fill_value=...): ...
+    def argmin(self, axis=..., fill_value=..., out=..., *, keepdims=...): ...
+    def argmax(self, axis=..., fill_value=..., out=..., *, keepdims=...): ...
+    def sort(self, axis=..., kind=..., order=..., endwith=..., fill_value=...): ...
+    def min(self, axis=..., out=..., fill_value=..., keepdims=...): ...
+    # NOTE: deprecated
+    # def tostring(self, fill_value=..., order=...): ...
+    def max(self, axis=..., out=..., fill_value=..., keepdims=...): ...
+    def ptp(self, axis=..., out=..., fill_value=..., keepdims=...): ...
+    def partition(self, *args, **kwargs): ...
+    def argpartition(self, *args, **kwargs): ...
+    def take(self, indices, axis=..., out=..., mode=...): ...
+    copy: Any
+    diagonal: Any
+    flatten: Any
+    repeat: Any
+    squeeze: Any
+    swapaxes: Any
+    T: Any
+    transpose: Any
+    def tolist(self, fill_value=...): ...
+    def tobytes(self, fill_value=..., order=...): ...
+    def tofile(self, fid, sep=..., format=...): ...
+    def toflex(self): ...
+    torecords: Any
+    def __reduce__(self): ...
+    def __deepcopy__(self, memo=...): ...
+
+class mvoid(MaskedArray[_ShapeType, _DType_co]):
+    def __new__(
+        self,
+        data,
+        mask=...,
+        dtype=...,
+        fill_value=...,
+        hardmask=...,
+        copy=...,
+        subok=...,
+    ): ...
+    def __getitem__(self, indx): ...
+    def __setitem__(self, indx, value): ...
+    def __iter__(self): ...
+    def __len__(self): ...
+    def filled(self, fill_value=...): ...
+    def tolist(self): ...
+
+def isMaskedArray(x): ...
+isarray = isMaskedArray
+isMA = isMaskedArray
+
+# 0D float64 array
+class MaskedConstant(MaskedArray[Any, dtype[float64]]):
+    def __new__(cls): ...
+    __class__: Any
+    def __array_finalize__(self, obj): ...
+    def __array_prepare__(self, obj, context=...): ...
+    def __array_wrap__(self, obj, context=...): ...
+    def __format__(self, format_spec): ...
+    def __reduce__(self): ...
+    def __iop__(self, other): ...
+    __iadd__: Any
+    __isub__: Any
+    __imul__: Any
+    __ifloordiv__: Any
+    __itruediv__: Any
+    __ipow__: Any
+    def copy(self, *args, **kwargs): ...
+    def __copy__(self): ...
+    def __deepcopy__(self, memo): ...
+    def __setattr__(self, attr, value): ...
+
+masked: MaskedConstant
+masked_singleton: MaskedConstant
+masked_array = MaskedArray
+
+def array(
+    data,
+    dtype=...,
+    copy=...,
+    order=...,
+    mask=...,
+    fill_value=...,
+    keep_mask=...,
+    hard_mask=...,
+    shrink=...,
+    subok=...,
+    ndmin=...,
+): ...
+def is_masked(x): ...
+
+class _extrema_operation(_MaskedUFunc):
+    compare: Any
+    fill_value_func: Any
+    def __init__(self, ufunc, compare, fill_value): ...
+    # NOTE: in practice `b` has a default value, but users should
+    # explicitly provide a value here as the default is deprecated
+    def __call__(self, a, b): ...
+    def reduce(self, target, axis=...): ...
+    def outer(self, a, b): ...
+
+def min(obj, axis=..., out=..., fill_value=..., keepdims=...): ...
+def max(obj, axis=..., out=..., fill_value=..., keepdims=...): ...
+def ptp(obj, axis=..., out=..., fill_value=..., keepdims=...): ...
+
+class _frommethod:
+    __name__: Any
+    __doc__: Any
+    reversed: Any
+    def __init__(self, methodname, reversed=...): ...
+    def getdoc(self): ...
+    def __call__(self, a, *args, **params): ...
+
+all: _frommethod
+anomalies: _frommethod
+anom: _frommethod
+any: _frommethod
+compress: _frommethod
+cumprod: _frommethod
+cumsum: _frommethod
+copy: _frommethod
+diagonal: _frommethod
+harden_mask: _frommethod
+ids: _frommethod
+mean: _frommethod
+nonzero: _frommethod
+prod: _frommethod
+product: _frommethod
+ravel: _frommethod
+repeat: _frommethod
+soften_mask: _frommethod
+std: _frommethod
+sum: _frommethod
+swapaxes: _frommethod
+trace: _frommethod
+var: _frommethod
+count: _frommethod
+argmin: _frommethod
+argmax: _frommethod
+
+minimum: _extrema_operation
+maximum: _extrema_operation
+
+def take(a, indices, axis=..., out=..., mode=...): ...
+def power(a, b, third=...): ...
+def argsort(a, axis=..., kind=..., order=..., endwith=..., fill_value=...): ...
+def sort(a, axis=..., kind=..., order=..., endwith=..., fill_value=...): ...
+def compressed(x): ...
+def concatenate(arrays, axis=...): ...
+def diag(v, k=...): ...
+def left_shift(a, n): ...
+def right_shift(a, n): ...
+def put(a, indices, values, mode=...): ...
+def putmask(a, mask, values): ...
+def transpose(a, axes=...): ...
+def reshape(a, new_shape, order=...): ...
+def resize(x, new_shape): ...
+def ndim(obj): ...
+def shape(obj): ...
+def size(obj, axis=...): ...
+def diff(a, /, n=..., axis=..., prepend=..., append=...): ...
+def where(condition, x=..., y=...): ...
+def choose(indices, choices, out=..., mode=...): ...
+def round(a, decimals=..., out=...): ...
+
+def inner(a, b): ...
+innerproduct = inner
+
+def outer(a, b): ...
+outerproduct = outer
+
+def correlate(a, v, mode=..., propagate_mask=...): ...
+def convolve(a, v, mode=..., propagate_mask=...): ...
+def allequal(a, b, fill_value=...): ...
+def allclose(a, b, masked_equal=..., rtol=..., atol=...): ...
+def asarray(a, dtype=..., order=...): ...
+def asanyarray(a, dtype=...): ...
+def fromflex(fxarray): ...
+
+class _convert2ma:
+    __doc__: Any
+    def __init__(self, funcname, params=...): ...
+    def getdoc(self): ...
+    def __call__(self, *args, **params): ...
+
+arange: _convert2ma
+empty: _convert2ma
+empty_like: _convert2ma
+frombuffer: _convert2ma
+fromfunction: _convert2ma
+identity: _convert2ma
+ones: _convert2ma
+zeros: _convert2ma
+
+def append(a, b, axis=...): ...
+def dot(a, b, strict=..., out=...): ...
+def mask_rowcols(a, axis=...): ...

.venv/lib/python3.11/site-packages/numpy/ma/extras.py

@@ -0,0 +1,2133 @@
+"""
+Masked arrays add-ons.
+
+A collection of utilities for `numpy.ma`.
+
+:author: Pierre Gerard-Marchant
+:contact: pierregm_at_uga_dot_edu
+:version: $Id: extras.py 3473 2007-10-29 15:18:13Z jarrod.millman $
+
+"""
+__all__ = [
+    'apply_along_axis', 'apply_over_axes', 'atleast_1d', 'atleast_2d',
+    'atleast_3d', 'average', 'clump_masked', 'clump_unmasked', 'column_stack',
+    'compress_cols', 'compress_nd', 'compress_rowcols', 'compress_rows',
+    'count_masked', 'corrcoef', 'cov', 'diagflat', 'dot', 'dstack', 'ediff1d',
+    'flatnotmasked_contiguous', 'flatnotmasked_edges', 'hsplit', 'hstack',
+    'isin', 'in1d', 'intersect1d', 'mask_cols', 'mask_rowcols', 'mask_rows',
+    'masked_all', 'masked_all_like', 'median', 'mr_', 'ndenumerate',
+    'notmasked_contiguous', 'notmasked_edges', 'polyfit', 'row_stack',
+    'setdiff1d', 'setxor1d', 'stack', 'unique', 'union1d', 'vander', 'vstack',
+    ]
+
+import itertools
+import warnings
+
+from . import core as ma
+from .core import (
+    MaskedArray, MAError, add, array, asarray, concatenate, filled, count,
+    getmask, getmaskarray, make_mask_descr, masked, masked_array, mask_or,
+    nomask, ones, sort, zeros, getdata, get_masked_subclass, dot
+    )
+
+import numpy as np
+from numpy import ndarray, array as nxarray
+from numpy.core.multiarray import normalize_axis_index
+from numpy.core.numeric import normalize_axis_tuple
+from numpy.lib.function_base import _ureduce
+from numpy.lib.index_tricks import AxisConcatenator
+
+
+def issequence(seq):
+    """
+    Is seq a sequence (ndarray, list or tuple)?
+
+    """
+    return isinstance(seq, (ndarray, tuple, list))
+
+
+def count_masked(arr, axis=None):
+    """
+    Count the number of masked elements along the given axis.
+
+    Parameters
+    ----------
+    arr : array_like
+        An array with (possibly) masked elements.
+    axis : int, optional
+        Axis along which to count. If None (default), a flattened
+        version of the array is used.
+
+    Returns
+    -------
+    count : int, ndarray
+        The total number of masked elements (axis=None) or the number
+        of masked elements along each slice of the given axis.
+
+    See Also
+    --------
+    MaskedArray.count : Count non-masked elements.
+
+    Examples
+    --------
+    >>> import numpy.ma as ma
+    >>> a = np.arange(9).reshape((3,3))
+    >>> a = ma.array(a)
+    >>> a[1, 0] = ma.masked
+    >>> a[1, 2] = ma.masked
+    >>> a[2, 1] = ma.masked
+    >>> a
+    masked_array(
+      data=[[0, 1, 2],
+            [--, 4, --],
+            [6, --, 8]],
+      mask=[[False, False, False],
+            [ True, False,  True],
+            [False,  True, False]],
+      fill_value=999999)
+    >>> ma.count_masked(a)
+    3
+
+    When the `axis` keyword is used an array is returned.
+
+    >>> ma.count_masked(a, axis=0)
+    array([1, 1, 1])
+    >>> ma.count_masked(a, axis=1)
+    array([0, 2, 1])
+
+    """
+    m = getmaskarray(arr)
+    return m.sum(axis)
+
+
+def masked_all(shape, dtype=float):
+    """
+    Empty masked array with all elements masked.
+
+    Return an empty masked array of the given shape and dtype, where all the
+    data are masked.
+
+    Parameters
+    ----------
+    shape : int or tuple of ints
+        Shape of the required MaskedArray, e.g., ``(2, 3)`` or ``2``.
+    dtype : dtype, optional
+        Data type of the output.
+
+    Returns
+    -------
+    a : MaskedArray
+        A masked array with all data masked.
+
+    See Also
+    --------
+    masked_all_like : Empty masked array modelled on an existing array.
+
+    Examples
+    --------
+    >>> import numpy.ma as ma
+    >>> ma.masked_all((3, 3))
+    masked_array(
+      data=[[--, --, --],
+            [--, --, --],
+            [--, --, --]],
+      mask=[[ True,  True,  True],
+            [ True,  True,  True],
+            [ True,  True,  True]],
+      fill_value=1e+20,
+      dtype=float64)
+
+    The `dtype` parameter defines the underlying data type.
+
+    >>> a = ma.masked_all((3, 3))
+    >>> a.dtype
+    dtype('float64')
+    >>> a = ma.masked_all((3, 3), dtype=np.int32)
+    >>> a.dtype
+    dtype('int32')
+
+    """
+    a = masked_array(np.empty(shape, dtype),
+                     mask=np.ones(shape, make_mask_descr(dtype)))
+    return a
+
+
+def masked_all_like(arr):
+    """
+    Empty masked array with the properties of an existing array.
+
+    Return an empty masked array of the same shape and dtype as
+    the array `arr`, where all the data are masked.
+
+    Parameters
+    ----------
+    arr : ndarray
+        An array describing the shape and dtype of the required MaskedArray.
+
+    Returns
+    -------
+    a : MaskedArray
+        A masked array with all data masked.
+
+    Raises
+    ------
+    AttributeError
+        If `arr` doesn't have a shape attribute (i.e. not an ndarray)
+
+    See Also
+    --------
+    masked_all : Empty masked array with all elements masked.
+
+    Examples
+    --------
+    >>> import numpy.ma as ma
+    >>> arr = np.zeros((2, 3), dtype=np.float32)
+    >>> arr
+    array([[0., 0., 0.],
+           [0., 0., 0.]], dtype=float32)
+    >>> ma.masked_all_like(arr)
+    masked_array(
+      data=[[--, --, --],
+            [--, --, --]],
+      mask=[[ True,  True,  True],
+            [ True,  True,  True]],
+      fill_value=1e+20,
+      dtype=float32)
+
+    The dtype of the masked array matches the dtype of `arr`.
+
+    >>> arr.dtype
+    dtype('float32')
+    >>> ma.masked_all_like(arr).dtype
+    dtype('float32')
+
+    """
+    a = np.empty_like(arr).view(MaskedArray)
+    a._mask = np.ones(a.shape, dtype=make_mask_descr(a.dtype))
+    return a
+
+
+#####--------------------------------------------------------------------------
+#---- --- Standard functions ---
+#####--------------------------------------------------------------------------
+class _fromnxfunction:
+    """
+    Defines a wrapper to adapt NumPy functions to masked arrays.
+
+
+    An instance of `_fromnxfunction` can be called with the same parameters
+    as the wrapped NumPy function. The docstring of `newfunc` is adapted from
+    the wrapped function as well, see `getdoc`.
+
+    This class should not be used directly. Instead, one of its extensions that
+    provides support for a specific type of input should be used.
+
+    Parameters
+    ----------
+    funcname : str
+        The name of the function to be adapted. The function should be
+        in the NumPy namespace (i.e. ``np.funcname``).
+
+    """
+
+    def __init__(self, funcname):
+        self.__name__ = funcname
+        self.__doc__ = self.getdoc()
+
+    def getdoc(self):
+        """
+        Retrieve the docstring and signature from the function.
+
+        The ``__doc__`` attribute of the function is used as the docstring for
+        the new masked array version of the function. A note on application
+        of the function to the mask is appended.
+
+        Parameters
+        ----------
+        None
+
+        """
+        npfunc = getattr(np, self.__name__, None)
+        doc = getattr(npfunc, '__doc__', None)
+        if doc:
+            sig = self.__name__ + ma.get_object_signature(npfunc)
+            doc = ma.doc_note(doc, "The function is applied to both the _data "
+                                   "and the _mask, if any.")
+            return '\n\n'.join((sig, doc))
+        return
+
+    def __call__(self, *args, **params):
+        pass
+
+
+class _fromnxfunction_single(_fromnxfunction):
+    """
+    A version of `_fromnxfunction` that is called with a single array
+    argument followed by auxiliary args that are passed verbatim for
+    both the data and mask calls.
+    """
+    def __call__(self, x, *args, **params):
+        func = getattr(np, self.__name__)
+        if isinstance(x, ndarray):
+            _d = func(x.__array__(), *args, **params)
+            _m = func(getmaskarray(x), *args, **params)
+            return masked_array(_d, mask=_m)
+        else:
+            _d = func(np.asarray(x), *args, **params)
+            _m = func(getmaskarray(x), *args, **params)
+            return masked_array(_d, mask=_m)
+
+
+class _fromnxfunction_seq(_fromnxfunction):
+    """
+    A version of `_fromnxfunction` that is called with a single sequence
+    of arrays followed by auxiliary args that are passed verbatim for
+    both the data and mask calls.
+    """
+    def __call__(self, x, *args, **params):
+        func = getattr(np, self.__name__)
+        _d = func(tuple([np.asarray(a) for a in x]), *args, **params)
+        _m = func(tuple([getmaskarray(a) for a in x]), *args, **params)
+        return masked_array(_d, mask=_m)
+
+
+class _fromnxfunction_args(_fromnxfunction):
+    """
+    A version of `_fromnxfunction` that is called with multiple array
+    arguments. The first non-array-like input marks the beginning of the
+    arguments that are passed verbatim for both the data and mask calls.
+    Array arguments are processed independently and the results are
+    returned in a list. If only one array is found, the return value is
+    just the processed array instead of a list.
+    """
+    def __call__(self, *args, **params):
+        func = getattr(np, self.__name__)
+        arrays = []
+        args = list(args)
+        while len(args) > 0 and issequence(args[0]):
+            arrays.append(args.pop(0))
+        res = []
+        for x in arrays:
+            _d = func(np.asarray(x), *args, **params)
+            _m = func(getmaskarray(x), *args, **params)
+            res.append(masked_array(_d, mask=_m))
+        if len(arrays) == 1:
+            return res[0]
+        return res
+
+
+class _fromnxfunction_allargs(_fromnxfunction):
+    """
+    A version of `_fromnxfunction` that is called with multiple array
+    arguments. Similar to `_fromnxfunction_args` except that all args
+    are converted to arrays even if they are not so already. This makes
+    it possible to process scalars as 1-D arrays. Only keyword arguments
+    are passed through verbatim for the data and mask calls. Arrays
+    arguments are processed independently and the results are returned
+    in a list. If only one arg is present, the return value is just the
+    processed array instead of a list.
+    """
+    def __call__(self, *args, **params):
+        func = getattr(np, self.__name__)
+        res = []
+        for x in args:
+            _d = func(np.asarray(x), **params)
+            _m = func(getmaskarray(x), **params)
+            res.append(masked_array(_d, mask=_m))
+        if len(args) == 1:
+            return res[0]
+        return res
+
+
+atleast_1d = _fromnxfunction_allargs('atleast_1d')
+atleast_2d = _fromnxfunction_allargs('atleast_2d')
+atleast_3d = _fromnxfunction_allargs('atleast_3d')
+
+vstack = row_stack = _fromnxfunction_seq('vstack')
+hstack = _fromnxfunction_seq('hstack')
+column_stack = _fromnxfunction_seq('column_stack')
+dstack = _fromnxfunction_seq('dstack')
+stack = _fromnxfunction_seq('stack')
+
+hsplit = _fromnxfunction_single('hsplit')
+
+diagflat = _fromnxfunction_single('diagflat')
+
+
+#####--------------------------------------------------------------------------
+#----
+#####--------------------------------------------------------------------------
+def flatten_inplace(seq):
+    """Flatten a sequence in place."""
+    k = 0
+    while (k != len(seq)):
+        while hasattr(seq[k], '__iter__'):
+            seq[k:(k + 1)] = seq[k]
+        k += 1
+    return seq
+
+
+def apply_along_axis(func1d, axis, arr, *args, **kwargs):
+    """
+    (This docstring should be overwritten)
+    """
+    arr = array(arr, copy=False, subok=True)
+    nd = arr.ndim
+    axis = normalize_axis_index(axis, nd)
+    ind = [0] * (nd - 1)
+    i = np.zeros(nd, 'O')
+    indlist = list(range(nd))
+    indlist.remove(axis)
+    i[axis] = slice(None, None)
+    outshape = np.asarray(arr.shape).take(indlist)
+    i.put(indlist, ind)
+    res = func1d(arr[tuple(i.tolist())], *args, **kwargs)
+    #  if res is a number, then we have a smaller output array
+    asscalar = np.isscalar(res)
+    if not asscalar:
+        try:
+            len(res)
+        except TypeError:
+            asscalar = True
+    # Note: we shouldn't set the dtype of the output from the first result
+    # so we force the type to object, and build a list of dtypes.  We'll
+    # just take the largest, to avoid some downcasting
+    dtypes = []
+    if asscalar:
+        dtypes.append(np.asarray(res).dtype)
+        outarr = zeros(outshape, object)
+        outarr[tuple(ind)] = res
+        Ntot = np.prod(outshape)
+        k = 1
+        while k < Ntot:
+            # increment the index
+            ind[-1] += 1
+            n = -1
+            while (ind[n] >= outshape[n]) and (n > (1 - nd)):
+                ind[n - 1] += 1
+                ind[n] = 0
+                n -= 1
+            i.put(indlist, ind)
+            res = func1d(arr[tuple(i.tolist())], *args, **kwargs)
+            outarr[tuple(ind)] = res
+            dtypes.append(asarray(res).dtype)
+            k += 1
+    else:
+        res = array(res, copy=False, subok=True)
+        j = i.copy()
+        j[axis] = ([slice(None, None)] * res.ndim)
+        j.put(indlist, ind)
+        Ntot = np.prod(outshape)
+        holdshape = outshape
+        outshape = list(arr.shape)
+        outshape[axis] = res.shape
+        dtypes.append(asarray(res).dtype)
+        outshape = flatten_inplace(outshape)
+        outarr = zeros(outshape, object)
+        outarr[tuple(flatten_inplace(j.tolist()))] = res
+        k = 1
+        while k < Ntot:
+            # increment the index
+            ind[-1] += 1
+            n = -1
+            while (ind[n] >= holdshape[n]) and (n > (1 - nd)):
+                ind[n - 1] += 1
+                ind[n] = 0
+                n -= 1
+            i.put(indlist, ind)
+            j.put(indlist, ind)
+            res = func1d(arr[tuple(i.tolist())], *args, **kwargs)
+            outarr[tuple(flatten_inplace(j.tolist()))] = res
+            dtypes.append(asarray(res).dtype)
+            k += 1
+    max_dtypes = np.dtype(np.asarray(dtypes).max())
+    if not hasattr(arr, '_mask'):
+        result = np.asarray(outarr, dtype=max_dtypes)
+    else:
+        result = asarray(outarr, dtype=max_dtypes)
+        result.fill_value = ma.default_fill_value(result)
+    return result
+apply_along_axis.__doc__ = np.apply_along_axis.__doc__
+
+
+def apply_over_axes(func, a, axes):
+    """
+    (This docstring will be overwritten)
+    """
+    val = asarray(a)
+    N = a.ndim
+    if array(axes).ndim == 0:
+        axes = (axes,)
+    for axis in axes:
+        if axis < 0:
+            axis = N + axis
+        args = (val, axis)
+        res = func(*args)
+        if res.ndim == val.ndim:
+            val = res
+        else:
+            res = ma.expand_dims(res, axis)
+            if res.ndim == val.ndim:
+                val = res
+            else:
+                raise ValueError("function is not returning "
+                        "an array of the correct shape")
+    return val
+
+
+if apply_over_axes.__doc__ is not None:
+    apply_over_axes.__doc__ = np.apply_over_axes.__doc__[
+        :np.apply_over_axes.__doc__.find('Notes')].rstrip() + \
+    """
+
+    Examples
+    --------
+    >>> a = np.ma.arange(24).reshape(2,3,4)
+    >>> a[:,0,1] = np.ma.masked
+    >>> a[:,1,:] = np.ma.masked
+    >>> a
+    masked_array(
+      data=[[[0, --, 2, 3],
+             [--, --, --, --],
+             [8, 9, 10, 11]],
+            [[12, --, 14, 15],
+             [--, --, --, --],
+             [20, 21, 22, 23]]],
+      mask=[[[False,  True, False, False],
+             [ True,  True,  True,  True],
+             [False, False, False, False]],
+            [[False,  True, False, False],
+             [ True,  True,  True,  True],
+             [False, False, False, False]]],
+      fill_value=999999)
+    >>> np.ma.apply_over_axes(np.ma.sum, a, [0,2])
+    masked_array(
+      data=[[[46],
+             [--],
+             [124]]],
+      mask=[[[False],
+             [ True],
+             [False]]],
+      fill_value=999999)
+
+    Tuple axis arguments to ufuncs are equivalent:
+
+    >>> np.ma.sum(a, axis=(0,2)).reshape((1,-1,1))
+    masked_array(
+      data=[[[46],
+             [--],
+             [124]]],
+      mask=[[[False],
+             [ True],
+             [False]]],
+      fill_value=999999)
+    """
+
+
+def average(a, axis=None, weights=None, returned=False, *,
+            keepdims=np._NoValue):
+    """
+    Return the weighted average of array over the given axis.
+
+    Parameters
+    ----------
+    a : array_like
+        Data to be averaged.
+        Masked entries are not taken into account in the computation.
+    axis : int, optional
+        Axis along which to average `a`. If None, averaging is done over
+        the flattened array.
+    weights : array_like, optional
+        The importance that each element has in the computation of the average.
+        The weights array can either be 1-D (in which case its length must be
+        the size of `a` along the given axis) or of the same shape as `a`.
+        If ``weights=None``, then all data in `a` are assumed to have a
+        weight equal to one.  The 1-D calculation is::
+
+            avg = sum(a * weights) / sum(weights)
+
+        The only constraint on `weights` is that `sum(weights)` must not be 0.
+    returned : bool, optional
+        Flag indicating whether a tuple ``(result, sum of weights)``
+        should be returned as output (True), or just the result (False).
+        Default is False.
+    keepdims : bool, optional
+        If this is set to True, the axes which are reduced are left
+        in the result as dimensions with size one. With this option,
+        the result will broadcast correctly against the original `a`.
+        *Note:* `keepdims` will not work with instances of `numpy.matrix`
+        or other classes whose methods do not support `keepdims`.
+
+        .. versionadded:: 1.23.0
+
+    Returns
+    -------
+    average, [sum_of_weights] : (tuple of) scalar or MaskedArray
+        The average along the specified axis. When returned is `True`,
+        return a tuple with the average as the first element and the sum
+        of the weights as the second element. The return type is `np.float64`
+        if `a` is of integer type and floats smaller than `float64`, or the
+        input data-type, otherwise. If returned, `sum_of_weights` is always
+        `float64`.
+
+    Examples
+    --------
+    >>> a = np.ma.array([1., 2., 3., 4.], mask=[False, False, True, True])
+    >>> np.ma.average(a, weights=[3, 1, 0, 0])
+    1.25
+
+    >>> x = np.ma.arange(6.).reshape(3, 2)
+    >>> x
+    masked_array(
+      data=[[0., 1.],
+            [2., 3.],
+            [4., 5.]],
+      mask=False,
+      fill_value=1e+20)
+    >>> avg, sumweights = np.ma.average(x, axis=0, weights=[1, 2, 3],
+    ...                                 returned=True)
+    >>> avg
+    masked_array(data=[2.6666666666666665, 3.6666666666666665],
+                 mask=[False, False],
+           fill_value=1e+20)
+
+    With ``keepdims=True``, the following result has shape (3, 1).
+
+    >>> np.ma.average(x, axis=1, keepdims=True)
+    masked_array(
+      data=[[0.5],
+            [2.5],
+            [4.5]],
+      mask=False,
+      fill_value=1e+20)
+    """
+    a = asarray(a)
+    m = getmask(a)
+
+    # inspired by 'average' in numpy/lib/function_base.py
+
+    if keepdims is np._NoValue:
+        # Don't pass on the keepdims argument if one wasn't given.
+        keepdims_kw = {}
+    else:
+        keepdims_kw = {'keepdims': keepdims}
+
+    if weights is None:
+        avg = a.mean(axis, **keepdims_kw)
+        scl = avg.dtype.type(a.count(axis))
+    else:
+        wgt = asarray(weights)
+
+        if issubclass(a.dtype.type, (np.integer, np.bool_)):
+            result_dtype = np.result_type(a.dtype, wgt.dtype, 'f8')
+        else:
+            result_dtype = np.result_type(a.dtype, wgt.dtype)
+
+        # Sanity checks
+        if a.shape != wgt.shape:
+            if axis is None:
+                raise TypeError(
+                    "Axis must be specified when shapes of a and weights "
+                    "differ.")
+            if wgt.ndim != 1:
+                raise TypeError(
+                    "1D weights expected when shapes of a and weights differ.")
+            if wgt.shape[0] != a.shape[axis]:
+                raise ValueError(
+                    "Length of weights not compatible with specified axis.")
+
+            # setup wgt to broadcast along axis
+            wgt = np.broadcast_to(wgt, (a.ndim-1)*(1,) + wgt.shape, subok=True)
+            wgt = wgt.swapaxes(-1, axis)
+
+        if m is not nomask:
+            wgt = wgt*(~a.mask)
+            wgt.mask |= a.mask
+
+        scl = wgt.sum(axis=axis, dtype=result_dtype, **keepdims_kw)
+        avg = np.multiply(a, wgt,
+                          dtype=result_dtype).sum(axis, **keepdims_kw) / scl
+
+    if returned:
+        if scl.shape != avg.shape:
+            scl = np.broadcast_to(scl, avg.shape).copy()
+        return avg, scl
+    else:
+        return avg
+
+
+def median(a, axis=None, out=None, overwrite_input=False, keepdims=False):
+    """
+    Compute the median along the specified axis.
+
+    Returns the median of the array elements.
+
+    Parameters
+    ----------
+    a : array_like
+        Input array or object that can be converted to an array.
+    axis : int, optional
+        Axis along which the medians are computed. The default (None) is
+        to compute the median along a flattened version of the array.
+    out : ndarray, optional
+        Alternative output array in which to place the result. It must
+        have the same shape and buffer length as the expected output
+        but the type will be cast if necessary.
+    overwrite_input : bool, optional
+        If True, then allow use of memory of input array (a) for
+        calculations. The input array will be modified by the call to
+        median. This will save memory when you do not need to preserve
+        the contents of the input array. Treat the input as undefined,
+        but it will probably be fully or partially sorted. Default is
+        False. Note that, if `overwrite_input` is True, and the input
+        is not already an `ndarray`, an error will be raised.
+    keepdims : bool, optional
+        If this is set to True, the axes which are reduced are left
+        in the result as dimensions with size one. With this option,
+        the result will broadcast correctly against the input array.
+
+        .. versionadded:: 1.10.0
+
+    Returns
+    -------
+    median : ndarray
+        A new array holding the result is returned unless out is
+        specified, in which case a reference to out is returned.
+        Return data-type is `float64` for integers and floats smaller than
+        `float64`, or the input data-type, otherwise.
+
+    See Also
+    --------
+    mean
+
+    Notes
+    -----
+    Given a vector ``V`` with ``N`` non masked values, the median of ``V``
+    is the middle value of a sorted copy of ``V`` (``Vs``) - i.e.
+    ``Vs[(N-1)/2]``, when ``N`` is odd, or ``{Vs[N/2 - 1] + Vs[N/2]}/2``
+    when ``N`` is even.
+
+    Examples
+    --------
+    >>> x = np.ma.array(np.arange(8), mask=[0]*4 + [1]*4)
+    >>> np.ma.median(x)
+    1.5
+
+    >>> x = np.ma.array(np.arange(10).reshape(2, 5), mask=[0]*6 + [1]*4)
+    >>> np.ma.median(x)
+    2.5
+    >>> np.ma.median(x, axis=-1, overwrite_input=True)
+    masked_array(data=[2.0, 5.0],
+                 mask=[False, False],
+           fill_value=1e+20)
+
+    """
+    if not hasattr(a, 'mask'):
+        m = np.median(getdata(a, subok=True), axis=axis,
+                      out=out, overwrite_input=overwrite_input,
+                      keepdims=keepdims)
+        if isinstance(m, np.ndarray) and 1 <= m.ndim:
+            return masked_array(m, copy=False)
+        else:
+            return m
+
+    return _ureduce(a, func=_median, keepdims=keepdims, axis=axis, out=out,
+                    overwrite_input=overwrite_input)
+
+
+def _median(a, axis=None, out=None, overwrite_input=False):
+    # when an unmasked NaN is present return it, so we need to sort the NaN
+    # values behind the mask
+    if np.issubdtype(a.dtype, np.inexact):
+        fill_value = np.inf
+    else:
+        fill_value = None
+    if overwrite_input:
+        if axis is None:
+            asorted = a.ravel()
+            asorted.sort(fill_value=fill_value)
+        else:
+            a.sort(axis=axis, fill_value=fill_value)
+            asorted = a
+    else:
+        asorted = sort(a, axis=axis, fill_value=fill_value)
+
+    if axis is None:
+        axis = 0
+    else:
+        axis = normalize_axis_index(axis, asorted.ndim)
+
+    if asorted.shape[axis] == 0:
+        # for empty axis integer indices fail so use slicing to get same result
+        # as median (which is mean of empty slice = nan)
+        indexer = [slice(None)] * asorted.ndim
+        indexer[axis] = slice(0, 0)
+        indexer = tuple(indexer)
+        return np.ma.mean(asorted[indexer], axis=axis, out=out)
+
+    if asorted.ndim == 1:
+        idx, odd = divmod(count(asorted), 2)
+        mid = asorted[idx + odd - 1:idx + 1]
+        if np.issubdtype(asorted.dtype, np.inexact) and asorted.size > 0:
+            # avoid inf / x = masked
+            s = mid.sum(out=out)
+            if not odd:
+                s = np.true_divide(s, 2., casting='safe', out=out)
+            s = np.lib.utils._median_nancheck(asorted, s, axis)
+        else:
+            s = mid.mean(out=out)
+
+        # if result is masked either the input contained enough
+        # minimum_fill_value so that it would be the median or all values
+        # masked
+        if np.ma.is_masked(s) and not np.all(asorted.mask):
+            return np.ma.minimum_fill_value(asorted)
+        return s
+
+    counts = count(asorted, axis=axis, keepdims=True)
+    h = counts // 2
+
+    # duplicate high if odd number of elements so mean does nothing
+    odd = counts % 2 == 1
+    l = np.where(odd, h, h-1)
+
+    lh = np.concatenate([l,h], axis=axis)
+
+    # get low and high median
+    low_high = np.take_along_axis(asorted, lh, axis=axis)
+
+    def replace_masked(s):
+        # Replace masked entries with minimum_full_value unless it all values
+        # are masked. This is required as the sort order of values equal or
+        # larger than the fill value is undefined and a valid value placed
+        # elsewhere, e.g. [4, --, inf].
+        if np.ma.is_masked(s):
+            rep = (~np.all(asorted.mask, axis=axis, keepdims=True)) & s.mask
+            s.data[rep] = np.ma.minimum_fill_value(asorted)
+            s.mask[rep] = False
+
+    replace_masked(low_high)
+
+    if np.issubdtype(asorted.dtype, np.inexact):
+        # avoid inf / x = masked
+        s = np.ma.sum(low_high, axis=axis, out=out)
+        np.true_divide(s.data, 2., casting='unsafe', out=s.data)
+
+        s = np.lib.utils._median_nancheck(asorted, s, axis)
+    else:
+        s = np.ma.mean(low_high, axis=axis, out=out)
+
+    return s
+
+
+def compress_nd(x, axis=None):
+    """Suppress slices from multiple dimensions which contain masked values.
+
+    Parameters
+    ----------
+    x : array_like, MaskedArray
+        The array to operate on. If not a MaskedArray instance (or if no array
+        elements are masked), `x` is interpreted as a MaskedArray with `mask`
+        set to `nomask`.
+    axis : tuple of ints or int, optional
+        Which dimensions to suppress slices from can be configured with this
+        parameter.
+        - If axis is a tuple of ints, those are the axes to suppress slices from.
+        - If axis is an int, then that is the only axis to suppress slices from.
+        - If axis is None, all axis are selected.
+
+    Returns
+    -------
+    compress_array : ndarray
+        The compressed array.
+    """
+    x = asarray(x)
+    m = getmask(x)
+    # Set axis to tuple of ints
+    if axis is None:
+        axis = tuple(range(x.ndim))
+    else:
+        axis = normalize_axis_tuple(axis, x.ndim)
+
+    # Nothing is masked: return x
+    if m is nomask or not m.any():
+        return x._data
+    # All is masked: return empty
+    if m.all():
+        return nxarray([])
+    # Filter elements through boolean indexing
+    data = x._data
+    for ax in axis:
+        axes = tuple(list(range(ax)) + list(range(ax + 1, x.ndim)))
+        data = data[(slice(None),)*ax + (~m.any(axis=axes),)]
+    return data
+
+
+def compress_rowcols(x, axis=None):
+    """
+    Suppress the rows and/or columns of a 2-D array that contain
+    masked values.
+
+    The suppression behavior is selected with the `axis` parameter.
+
+    - If axis is None, both rows and columns are suppressed.
+    - If axis is 0, only rows are suppressed.
+    - If axis is 1 or -1, only columns are suppressed.
+
+    Parameters
+    ----------
+    x : array_like, MaskedArray
+        The array to operate on.  If not a MaskedArray instance (or if no array
+        elements are masked), `x` is interpreted as a MaskedArray with
+        `mask` set to `nomask`. Must be a 2D array.
+    axis : int, optional
+        Axis along which to perform the operation. Default is None.
+
+    Returns
+    -------
+    compressed_array : ndarray
+        The compressed array.
+
+    Examples
+    --------
+    >>> x = np.ma.array(np.arange(9).reshape(3, 3), mask=[[1, 0, 0],
+    ...                                                   [1, 0, 0],
+    ...                                                   [0, 0, 0]])
+    >>> x
+    masked_array(
+      data=[[--, 1, 2],
+            [--, 4, 5],
+            [6, 7, 8]],
+      mask=[[ True, False, False],
+            [ True, False, False],
+            [False, False, False]],
+      fill_value=999999)
+
+    >>> np.ma.compress_rowcols(x)
+    array([[7, 8]])
+    >>> np.ma.compress_rowcols(x, 0)
+    array([[6, 7, 8]])
+    >>> np.ma.compress_rowcols(x, 1)
+    array([[1, 2],
+           [4, 5],
+           [7, 8]])
+
+    """
+    if asarray(x).ndim != 2:
+        raise NotImplementedError("compress_rowcols works for 2D arrays only.")
+    return compress_nd(x, axis=axis)
+
+
+def compress_rows(a):
+    """
+    Suppress whole rows of a 2-D array that contain masked values.
+
+    This is equivalent to ``np.ma.compress_rowcols(a, 0)``, see
+    `compress_rowcols` for details.
+
+    See Also
+    --------
+    compress_rowcols
+
+    """
+    a = asarray(a)
+    if a.ndim != 2:
+        raise NotImplementedError("compress_rows works for 2D arrays only.")
+    return compress_rowcols(a, 0)
+
+
+def compress_cols(a):
+    """
+    Suppress whole columns of a 2-D array that contain masked values.
+
+    This is equivalent to ``np.ma.compress_rowcols(a, 1)``, see
+    `compress_rowcols` for details.
+
+    See Also
+    --------
+    compress_rowcols
+
+    """
+    a = asarray(a)
+    if a.ndim != 2:
+        raise NotImplementedError("compress_cols works for 2D arrays only.")
+    return compress_rowcols(a, 1)
+
+
+def mask_rowcols(a, axis=None):
+    """
+    Mask rows and/or columns of a 2D array that contain masked values.
+
+    Mask whole rows and/or columns of a 2D array that contain
+    masked values.  The masking behavior is selected using the
+    `axis` parameter.
+
+      - If `axis` is None, rows *and* columns are masked.
+      - If `axis` is 0, only rows are masked.
+      - If `axis` is 1 or -1, only columns are masked.
+
+    Parameters
+    ----------
+    a : array_like, MaskedArray
+        The array to mask.  If not a MaskedArray instance (or if no array
+        elements are masked), the result is a MaskedArray with `mask` set
+        to `nomask` (False). Must be a 2D array.
+    axis : int, optional
+        Axis along which to perform the operation. If None, applies to a
+        flattened version of the array.
+
+    Returns
+    -------
+    a : MaskedArray
+        A modified version of the input array, masked depending on the value
+        of the `axis` parameter.
+
+    Raises
+    ------
+    NotImplementedError
+        If input array `a` is not 2D.
+
+    See Also
+    --------
+    mask_rows : Mask rows of a 2D array that contain masked values.
+    mask_cols : Mask cols of a 2D array that contain masked values.
+    masked_where : Mask where a condition is met.
+
+    Notes
+    -----
+    The input array's mask is modified by this function.
+
+    Examples
+    --------
+    >>> import numpy.ma as ma
+    >>> a = np.zeros((3, 3), dtype=int)
+    >>> a[1, 1] = 1
+    >>> a
+    array([[0, 0, 0],
+           [0, 1, 0],
+           [0, 0, 0]])
+    >>> a = ma.masked_equal(a, 1)
+    >>> a
+    masked_array(
+      data=[[0, 0, 0],
+            [0, --, 0],
+            [0, 0, 0]],
+      mask=[[False, False, False],
+            [False,  True, False],
+            [False, False, False]],
+      fill_value=1)
+    >>> ma.mask_rowcols(a)
+    masked_array(
+      data=[[0, --, 0],
+            [--, --, --],
+            [0, --, 0]],
+      mask=[[False,  True, False],
+            [ True,  True,  True],
+            [False,  True, False]],
+      fill_value=1)
+
+    """
+    a = array(a, subok=False)
+    if a.ndim != 2:
+        raise NotImplementedError("mask_rowcols works for 2D arrays only.")
+    m = getmask(a)
+    # Nothing is masked: return a
+    if m is nomask or not m.any():
+        return a
+    maskedval = m.nonzero()
+    a._mask = a._mask.copy()
+    if not axis:
+        a[np.unique(maskedval[0])] = masked
+    if axis in [None, 1, -1]:
+        a[:, np.unique(maskedval[1])] = masked
+    return a
+
+
+def mask_rows(a, axis=np._NoValue):
+    """
+    Mask rows of a 2D array that contain masked values.
+
+    This function is a shortcut to ``mask_rowcols`` with `axis` equal to 0.
+
+    See Also
+    --------
+    mask_rowcols : Mask rows and/or columns of a 2D array.
+    masked_where : Mask where a condition is met.
+
+    Examples
+    --------
+    >>> import numpy.ma as ma
+    >>> a = np.zeros((3, 3), dtype=int)
+    >>> a[1, 1] = 1
+    >>> a
+    array([[0, 0, 0],
+           [0, 1, 0],
+           [0, 0, 0]])
+    >>> a = ma.masked_equal(a, 1)
+    >>> a
+    masked_array(
+      data=[[0, 0, 0],
+            [0, --, 0],
+            [0, 0, 0]],
+      mask=[[False, False, False],
+            [False,  True, False],
+            [False, False, False]],
+      fill_value=1)
+
+    >>> ma.mask_rows(a)
+    masked_array(
+      data=[[0, 0, 0],
+            [--, --, --],
+            [0, 0, 0]],
+      mask=[[False, False, False],
+            [ True,  True,  True],
+            [False, False, False]],
+      fill_value=1)
+
+    """
+    if axis is not np._NoValue:
+        # remove the axis argument when this deprecation expires
+        # NumPy 1.18.0, 2019-11-28
+        warnings.warn(
+            "The axis argument has always been ignored, in future passing it "
+            "will raise TypeError", DeprecationWarning, stacklevel=2)
+    return mask_rowcols(a, 0)
+
+
+def mask_cols(a, axis=np._NoValue):
+    """
+    Mask columns of a 2D array that contain masked values.
+
+    This function is a shortcut to ``mask_rowcols`` with `axis` equal to 1.
+
+    See Also
+    --------
+    mask_rowcols : Mask rows and/or columns of a 2D array.
+    masked_where : Mask where a condition is met.
+
+    Examples
+    --------
+    >>> import numpy.ma as ma
+    >>> a = np.zeros((3, 3), dtype=int)
+    >>> a[1, 1] = 1
+    >>> a
+    array([[0, 0, 0],
+           [0, 1, 0],
+           [0, 0, 0]])
+    >>> a = ma.masked_equal(a, 1)
+    >>> a
+    masked_array(
+      data=[[0, 0, 0],
+            [0, --, 0],
+            [0, 0, 0]],
+      mask=[[False, False, False],
+            [False,  True, False],
+            [False, False, False]],
+      fill_value=1)
+    >>> ma.mask_cols(a)
+    masked_array(
+      data=[[0, --, 0],
+            [0, --, 0],
+            [0, --, 0]],
+      mask=[[False,  True, False],
+            [False,  True, False],
+            [False,  True, False]],
+      fill_value=1)
+
+    """
+    if axis is not np._NoValue:
+        # remove the axis argument when this deprecation expires
+        # NumPy 1.18.0, 2019-11-28
+        warnings.warn(
+            "The axis argument has always been ignored, in future passing it "
+            "will raise TypeError", DeprecationWarning, stacklevel=2)
+    return mask_rowcols(a, 1)
+
+
+#####--------------------------------------------------------------------------
+#---- --- arraysetops ---
+#####--------------------------------------------------------------------------
+
+def ediff1d(arr, to_end=None, to_begin=None):
+    """
+    Compute the differences between consecutive elements of an array.
+
+    This function is the equivalent of `numpy.ediff1d` that takes masked
+    values into account, see `numpy.ediff1d` for details.
+
+    See Also
+    --------
+    numpy.ediff1d : Equivalent function for ndarrays.
+
+    """
+    arr = ma.asanyarray(arr).flat
+    ed = arr[1:] - arr[:-1]
+    arrays = [ed]
+    #
+    if to_begin is not None:
+        arrays.insert(0, to_begin)
+    if to_end is not None:
+        arrays.append(to_end)
+    #
+    if len(arrays) != 1:
+        # We'll save ourselves a copy of a potentially large array in the common
+        # case where neither to_begin or to_end was given.
+        ed = hstack(arrays)
+    #
+    return ed
+
+
+def unique(ar1, return_index=False, return_inverse=False):
+    """
+    Finds the unique elements of an array.
+
+    Masked values are considered the same element (masked). The output array
+    is always a masked array. See `numpy.unique` for more details.
+
+    See Also
+    --------
+    numpy.unique : Equivalent function for ndarrays.
+
+    Examples
+    --------
+    >>> import numpy.ma as ma
+    >>> a = [1, 2, 1000, 2, 3]
+    >>> mask = [0, 0, 1, 0, 0]
+    >>> masked_a = ma.masked_array(a, mask)
+    >>> masked_a
+    masked_array(data=[1, 2, --, 2, 3],
+                mask=[False, False,  True, False, False],
+        fill_value=999999)
+    >>> ma.unique(masked_a)
+    masked_array(data=[1, 2, 3, --],
+                mask=[False, False, False,  True],
+        fill_value=999999)
+    >>> ma.unique(masked_a, return_index=True)
+    (masked_array(data=[1, 2, 3, --],
+                mask=[False, False, False,  True],
+        fill_value=999999), array([0, 1, 4, 2]))
+    >>> ma.unique(masked_a, return_inverse=True)
+    (masked_array(data=[1, 2, 3, --],
+                mask=[False, False, False,  True],
+        fill_value=999999), array([0, 1, 3, 1, 2]))
+    >>> ma.unique(masked_a, return_index=True, return_inverse=True)
+    (masked_array(data=[1, 2, 3, --],
+                mask=[False, False, False,  True],
+        fill_value=999999), array([0, 1, 4, 2]), array([0, 1, 3, 1, 2]))
+    """
+    output = np.unique(ar1,
+                       return_index=return_index,
+                       return_inverse=return_inverse)
+    if isinstance(output, tuple):
+        output = list(output)
+        output[0] = output[0].view(MaskedArray)
+        output = tuple(output)
+    else:
+        output = output.view(MaskedArray)
+    return output
+
+
+def intersect1d(ar1, ar2, assume_unique=False):
+    """
+    Returns the unique elements common to both arrays.
+
+    Masked values are considered equal one to the other.
+    The output is always a masked array.
+
+    See `numpy.intersect1d` for more details.
+
+    See Also
+    --------
+    numpy.intersect1d : Equivalent function for ndarrays.
+
+    Examples
+    --------
+    >>> x = np.ma.array([1, 3, 3, 3], mask=[0, 0, 0, 1])
+    >>> y = np.ma.array([3, 1, 1, 1], mask=[0, 0, 0, 1])
+    >>> np.ma.intersect1d(x, y)
+    masked_array(data=[1, 3, --],
+                 mask=[False, False,  True],
+           fill_value=999999)
+
+    """
+    if assume_unique:
+        aux = ma.concatenate((ar1, ar2))
+    else:
+        # Might be faster than unique( intersect1d( ar1, ar2 ) )?
+        aux = ma.concatenate((unique(ar1), unique(ar2)))
+    aux.sort()
+    return aux[:-1][aux[1:] == aux[:-1]]
+
+
+def setxor1d(ar1, ar2, assume_unique=False):
+    """
+    Set exclusive-or of 1-D arrays with unique elements.
+
+    The output is always a masked array. See `numpy.setxor1d` for more details.
+
+    See Also
+    --------
+    numpy.setxor1d : Equivalent function for ndarrays.
+
+    """
+    if not assume_unique:
+        ar1 = unique(ar1)
+        ar2 = unique(ar2)
+
+    aux = ma.concatenate((ar1, ar2))
+    if aux.size == 0:
+        return aux
+    aux.sort()
+    auxf = aux.filled()
+#    flag = ediff1d( aux, to_end = 1, to_begin = 1 ) == 0
+    flag = ma.concatenate(([True], (auxf[1:] != auxf[:-1]), [True]))
+#    flag2 = ediff1d( flag ) == 0
+    flag2 = (flag[1:] == flag[:-1])
+    return aux[flag2]
+
+
+def in1d(ar1, ar2, assume_unique=False, invert=False):
+    """
+    Test whether each element of an array is also present in a second
+    array.
+
+    The output is always a masked array. See `numpy.in1d` for more details.
+
+    We recommend using :func:`isin` instead of `in1d` for new code.
+
+    See Also
+    --------
+    isin       : Version of this function that preserves the shape of ar1.
+    numpy.in1d : Equivalent function for ndarrays.
+
+    Notes
+    -----
+    .. versionadded:: 1.4.0
+
+    """
+    if not assume_unique:
+        ar1, rev_idx = unique(ar1, return_inverse=True)
+        ar2 = unique(ar2)
+
+    ar = ma.concatenate((ar1, ar2))
+    # We need this to be a stable sort, so always use 'mergesort'
+    # here. The values from the first array should always come before
+    # the values from the second array.
+    order = ar.argsort(kind='mergesort')
+    sar = ar[order]
+    if invert:
+        bool_ar = (sar[1:] != sar[:-1])
+    else:
+        bool_ar = (sar[1:] == sar[:-1])
+    flag = ma.concatenate((bool_ar, [invert]))
+    indx = order.argsort(kind='mergesort')[:len(ar1)]
+
+    if assume_unique:
+        return flag[indx]
+    else:
+        return flag[indx][rev_idx]
+
+
+def isin(element, test_elements, assume_unique=False, invert=False):
+    """
+    Calculates `element in test_elements`, broadcasting over
+    `element` only.
+
+    The output is always a masked array of the same shape as `element`.
+    See `numpy.isin` for more details.
+
+    See Also
+    --------
+    in1d       : Flattened version of this function.
+    numpy.isin : Equivalent function for ndarrays.
+
+    Notes
+    -----
+    .. versionadded:: 1.13.0
+
+    """
+    element = ma.asarray(element)
+    return in1d(element, test_elements, assume_unique=assume_unique,
+                invert=invert).reshape(element.shape)
+
+
+def union1d(ar1, ar2):
+    """
+    Union of two arrays.
+
+    The output is always a masked array. See `numpy.union1d` for more details.
+
+    See Also
+    --------
+    numpy.union1d : Equivalent function for ndarrays.
+
+    """
+    return unique(ma.concatenate((ar1, ar2), axis=None))
+
+
+def setdiff1d(ar1, ar2, assume_unique=False):
+    """
+    Set difference of 1D arrays with unique elements.
+
+    The output is always a masked array. See `numpy.setdiff1d` for more
+    details.
+
+    See Also
+    --------
+    numpy.setdiff1d : Equivalent function for ndarrays.
+
+    Examples
+    --------
+    >>> x = np.ma.array([1, 2, 3, 4], mask=[0, 1, 0, 1])
+    >>> np.ma.setdiff1d(x, [1, 2])
+    masked_array(data=[3, --],
+                 mask=[False,  True],
+           fill_value=999999)
+
+    """
+    if assume_unique:
+        ar1 = ma.asarray(ar1).ravel()
+    else:
+        ar1 = unique(ar1)
+        ar2 = unique(ar2)
+    return ar1[in1d(ar1, ar2, assume_unique=True, invert=True)]
+
+
+###############################################################################
+#                                Covariance                                   #
+###############################################################################
+
+
+def _covhelper(x, y=None, rowvar=True, allow_masked=True):
+    """
+    Private function for the computation of covariance and correlation
+    coefficients.
+
+    """
+    x = ma.array(x, ndmin=2, copy=True, dtype=float)
+    xmask = ma.getmaskarray(x)
+    # Quick exit if we can't process masked data
+    if not allow_masked and xmask.any():
+        raise ValueError("Cannot process masked data.")
+    #
+    if x.shape[0] == 1:
+        rowvar = True
+    # Make sure that rowvar is either 0 or 1
+    rowvar = int(bool(rowvar))
+    axis = 1 - rowvar
+    if rowvar:
+        tup = (slice(None), None)
+    else:
+        tup = (None, slice(None))
+    #
+    if y is None:
+        xnotmask = np.logical_not(xmask).astype(int)
+    else:
+        y = array(y, copy=False, ndmin=2, dtype=float)
+        ymask = ma.getmaskarray(y)
+        if not allow_masked and ymask.any():
+            raise ValueError("Cannot process masked data.")
+        if xmask.any() or ymask.any():
+            if y.shape == x.shape:
+                # Define some common mask
+                common_mask = np.logical_or(xmask, ymask)
+                if common_mask is not nomask:
+                    xmask = x._mask = y._mask = ymask = common_mask
+                    x._sharedmask = False
+                    y._sharedmask = False
+        x = ma.concatenate((x, y), axis)
+        xnotmask = np.logical_not(np.concatenate((xmask, ymask), axis)).astype(int)
+    x -= x.mean(axis=rowvar)[tup]
+    return (x, xnotmask, rowvar)
+
+
+def cov(x, y=None, rowvar=True, bias=False, allow_masked=True, ddof=None):
+    """
+    Estimate the covariance matrix.
+
+    Except for the handling of missing data this function does the same as
+    `numpy.cov`. For more details and examples, see `numpy.cov`.
+
+    By default, masked values are recognized as such. If `x` and `y` have the
+    same shape, a common mask is allocated: if ``x[i,j]`` is masked, then
+    ``y[i,j]`` will also be masked.
+    Setting `allow_masked` to False will raise an exception if values are
+    missing in either of the input arrays.
+
+    Parameters
+    ----------
+    x : array_like
+        A 1-D or 2-D array containing multiple variables and observations.
+        Each row of `x` represents a variable, and each column a single
+        observation of all those variables. Also see `rowvar` below.
+    y : array_like, optional
+        An additional set of variables and observations. `y` has the same
+        shape as `x`.
+    rowvar : bool, optional
+        If `rowvar` is True (default), then each row represents a
+        variable, with observations in the columns. Otherwise, the relationship
+        is transposed: each column represents a variable, while the rows
+        contain observations.
+    bias : bool, optional
+        Default normalization (False) is by ``(N-1)``, where ``N`` is the
+        number of observations given (unbiased estimate). If `bias` is True,
+        then normalization is by ``N``. This keyword can be overridden by
+        the keyword ``ddof`` in numpy versions >= 1.5.
+    allow_masked : bool, optional
+        If True, masked values are propagated pair-wise: if a value is masked
+        in `x`, the corresponding value is masked in `y`.
+        If False, raises a `ValueError` exception when some values are missing.
+    ddof : {None, int}, optional
+        If not ``None`` normalization is by ``(N - ddof)``, where ``N`` is
+        the number of observations; this overrides the value implied by
+        ``bias``. The default value is ``None``.
+
+        .. versionadded:: 1.5
+
+    Raises
+    ------
+    ValueError
+        Raised if some values are missing and `allow_masked` is False.
+
+    See Also
+    --------
+    numpy.cov
+
+    """
+    # Check inputs
+    if ddof is not None and ddof != int(ddof):
+        raise ValueError("ddof must be an integer")
+    # Set up ddof
+    if ddof is None:
+        if bias:
+            ddof = 0
+        else:
+            ddof = 1
+
+    (x, xnotmask, rowvar) = _covhelper(x, y, rowvar, allow_masked)
+    if not rowvar:
+        fact = np.dot(xnotmask.T, xnotmask) * 1. - ddof
+        result = (dot(x.T, x.conj(), strict=False) / fact).squeeze()
+    else:
+        fact = np.dot(xnotmask, xnotmask.T) * 1. - ddof
+        result = (dot(x, x.T.conj(), strict=False) / fact).squeeze()
+    return result
+
+
+def corrcoef(x, y=None, rowvar=True, bias=np._NoValue, allow_masked=True,
+             ddof=np._NoValue):
+    """
+    Return Pearson product-moment correlation coefficients.
+
+    Except for the handling of missing data this function does the same as
+    `numpy.corrcoef`. For more details and examples, see `numpy.corrcoef`.
+
+    Parameters
+    ----------
+    x : array_like
+        A 1-D or 2-D array containing multiple variables and observations.
+        Each row of `x` represents a variable, and each column a single
+        observation of all those variables. Also see `rowvar` below.
+    y : array_like, optional
+        An additional set of variables and observations. `y` has the same
+        shape as `x`.
+    rowvar : bool, optional
+        If `rowvar` is True (default), then each row represents a
+        variable, with observations in the columns. Otherwise, the relationship
+        is transposed: each column represents a variable, while the rows
+        contain observations.
+    bias : _NoValue, optional
+        Has no effect, do not use.
+
+        .. deprecated:: 1.10.0
+    allow_masked : bool, optional
+        If True, masked values are propagated pair-wise: if a value is masked
+        in `x`, the corresponding value is masked in `y`.
+        If False, raises an exception.  Because `bias` is deprecated, this
+        argument needs to be treated as keyword only to avoid a warning.
+    ddof : _NoValue, optional
+        Has no effect, do not use.
+
+        .. deprecated:: 1.10.0
+
+    See Also
+    --------
+    numpy.corrcoef : Equivalent function in top-level NumPy module.
+    cov : Estimate the covariance matrix.
+
+    Notes
+    -----
+    This function accepts but discards arguments `bias` and `ddof`.  This is
+    for backwards compatibility with previous versions of this function.  These
+    arguments had no effect on the return values of the function and can be
+    safely ignored in this and previous versions of numpy.
+    """
+    msg = 'bias and ddof have no effect and are deprecated'
+    if bias is not np._NoValue or ddof is not np._NoValue:
+        # 2015-03-15, 1.10
+        warnings.warn(msg, DeprecationWarning, stacklevel=2)
+    # Get the data
+    (x, xnotmask, rowvar) = _covhelper(x, y, rowvar, allow_masked)
+    # Compute the covariance matrix
+    if not rowvar:
+        fact = np.dot(xnotmask.T, xnotmask) * 1.
+        c = (dot(x.T, x.conj(), strict=False) / fact).squeeze()
+    else:
+        fact = np.dot(xnotmask, xnotmask.T) * 1.
+        c = (dot(x, x.T.conj(), strict=False) / fact).squeeze()
+    # Check whether we have a scalar
+    try:
+        diag = ma.diagonal(c)
+    except ValueError:
+        return 1
+    #
+    if xnotmask.all():
+        _denom = ma.sqrt(ma.multiply.outer(diag, diag))
+    else:
+        _denom = diagflat(diag)
+        _denom._sharedmask = False  # We know return is always a copy
+        n = x.shape[1 - rowvar]
+        if rowvar:
+            for i in range(n - 1):
+                for j in range(i + 1, n):
+                    _x = mask_cols(vstack((x[i], x[j]))).var(axis=1)
+                    _denom[i, j] = _denom[j, i] = ma.sqrt(ma.multiply.reduce(_x))
+        else:
+            for i in range(n - 1):
+                for j in range(i + 1, n):
+                    _x = mask_cols(
+                            vstack((x[:, i], x[:, j]))).var(axis=1)
+                    _denom[i, j] = _denom[j, i] = ma.sqrt(ma.multiply.reduce(_x))
+    return c / _denom
+
+#####--------------------------------------------------------------------------
+#---- --- Concatenation helpers ---
+#####--------------------------------------------------------------------------
+
+class MAxisConcatenator(AxisConcatenator):
+    """
+    Translate slice objects to concatenation along an axis.
+
+    For documentation on usage, see `mr_class`.
+
+    See Also
+    --------
+    mr_class
+
+    """
+    concatenate = staticmethod(concatenate)
+
+    @classmethod
+    def makemat(cls, arr):
+        # There used to be a view as np.matrix here, but we may eventually
+        # deprecate that class. In preparation, we use the unmasked version
+        # to construct the matrix (with copy=False for backwards compatibility
+        # with the .view)
+        data = super().makemat(arr.data, copy=False)
+        return array(data, mask=arr.mask)
+
+    def __getitem__(self, key):
+        # matrix builder syntax, like 'a, b; c, d'
+        if isinstance(key, str):
+            raise MAError("Unavailable for masked array.")
+
+        return super().__getitem__(key)
+
+
+class mr_class(MAxisConcatenator):
+    """
+    Translate slice objects to concatenation along the first axis.
+
+    This is the masked array version of `lib.index_tricks.RClass`.
+
+    See Also
+    --------
+    lib.index_tricks.RClass
+
+    Examples
+    --------
+    >>> np.ma.mr_[np.ma.array([1,2,3]), 0, 0, np.ma.array([4,5,6])]
+    masked_array(data=[1, 2, 3, ..., 4, 5, 6],
+                 mask=False,
+           fill_value=999999)
+
+    """
+    def __init__(self):
+        MAxisConcatenator.__init__(self, 0)
+
+mr_ = mr_class()
+
+
+#####--------------------------------------------------------------------------
+#---- Find unmasked data ---
+#####--------------------------------------------------------------------------
+
+def ndenumerate(a, compressed=True):
+    """
+    Multidimensional index iterator.
+
+    Return an iterator yielding pairs of array coordinates and values,
+    skipping elements that are masked. With `compressed=False`,
+    `ma.masked` is yielded as the value of masked elements. This
+    behavior differs from that of `numpy.ndenumerate`, which yields the
+    value of the underlying data array.
+
+    Notes
+    -----
+    .. versionadded:: 1.23.0
+
+    Parameters
+    ----------
+    a : array_like
+        An array with (possibly) masked elements.
+    compressed : bool, optional
+        If True (default), masked elements are skipped.
+
+    See Also
+    --------
+    numpy.ndenumerate : Equivalent function ignoring any mask.
+
+    Examples
+    --------
+    >>> a = np.ma.arange(9).reshape((3, 3))
+    >>> a[1, 0] = np.ma.masked
+    >>> a[1, 2] = np.ma.masked
+    >>> a[2, 1] = np.ma.masked
+    >>> a
+    masked_array(
+      data=[[0, 1, 2],
+            [--, 4, --],
+            [6, --, 8]],
+      mask=[[False, False, False],
+            [ True, False,  True],
+            [False,  True, False]],
+      fill_value=999999)
+    >>> for index, x in np.ma.ndenumerate(a):
+    ...     print(index, x)
+    (0, 0) 0
+    (0, 1) 1
+    (0, 2) 2
+    (1, 1) 4
+    (2, 0) 6
+    (2, 2) 8
+
+    >>> for index, x in np.ma.ndenumerate(a, compressed=False):
+    ...     print(index, x)
+    (0, 0) 0
+    (0, 1) 1
+    (0, 2) 2
+    (1, 0) --
+    (1, 1) 4
+    (1, 2) --
+    (2, 0) 6
+    (2, 1) --
+    (2, 2) 8
+    """
+    for it, mask in zip(np.ndenumerate(a), getmaskarray(a).flat):
+        if not mask:
+            yield it
+        elif not compressed:
+            yield it[0], masked
+
+
+def flatnotmasked_edges(a):
+    """
+    Find the indices of the first and last unmasked values.
+
+    Expects a 1-D `MaskedArray`, returns None if all values are masked.
+
+    Parameters
+    ----------
+    a : array_like
+        Input 1-D `MaskedArray`
+
+    Returns
+    -------
+    edges : ndarray or None
+        The indices of first and last non-masked value in the array.
+        Returns None if all values are masked.
+
+    See Also
+    --------
+    flatnotmasked_contiguous, notmasked_contiguous, notmasked_edges
+    clump_masked, clump_unmasked
+
+    Notes
+    -----
+    Only accepts 1-D arrays.
+
+    Examples
+    --------
+    >>> a = np.ma.arange(10)
+    >>> np.ma.flatnotmasked_edges(a)
+    array([0, 9])
+
+    >>> mask = (a < 3) | (a > 8) | (a == 5)
+    >>> a[mask] = np.ma.masked
+    >>> np.array(a[~a.mask])
+    array([3, 4, 6, 7, 8])
+
+    >>> np.ma.flatnotmasked_edges(a)
+    array([3, 8])
+
+    >>> a[:] = np.ma.masked
+    >>> print(np.ma.flatnotmasked_edges(a))
+    None
+
+    """
+    m = getmask(a)
+    if m is nomask or not np.any(m):
+        return np.array([0, a.size - 1])
+    unmasked = np.flatnonzero(~m)
+    if len(unmasked) > 0:
+        return unmasked[[0, -1]]
+    else:
+        return None
+
+
+def notmasked_edges(a, axis=None):
+    """
+    Find the indices of the first and last unmasked values along an axis.
+
+    If all values are masked, return None.  Otherwise, return a list
+    of two tuples, corresponding to the indices of the first and last
+    unmasked values respectively.
+
+    Parameters
+    ----------
+    a : array_like
+        The input array.
+    axis : int, optional
+        Axis along which to perform the operation.
+        If None (default), applies to a flattened version of the array.
+
+    Returns
+    -------
+    edges : ndarray or list
+        An array of start and end indexes if there are any masked data in
+        the array. If there are no masked data in the array, `edges` is a
+        list of the first and last index.
+
+    See Also
+    --------
+    flatnotmasked_contiguous, flatnotmasked_edges, notmasked_contiguous
+    clump_masked, clump_unmasked
+
+    Examples
+    --------
+    >>> a = np.arange(9).reshape((3, 3))
+    >>> m = np.zeros_like(a)
+    >>> m[1:, 1:] = 1
+
+    >>> am = np.ma.array(a, mask=m)
+    >>> np.array(am[~am.mask])
+    array([0, 1, 2, 3, 6])
+
+    >>> np.ma.notmasked_edges(am)
+    array([0, 6])
+
+    """
+    a = asarray(a)
+    if axis is None or a.ndim == 1:
+        return flatnotmasked_edges(a)
+    m = getmaskarray(a)
+    idx = array(np.indices(a.shape), mask=np.asarray([m] * a.ndim))
+    return [tuple([idx[i].min(axis).compressed() for i in range(a.ndim)]),
+            tuple([idx[i].max(axis).compressed() for i in range(a.ndim)]), ]
+
+
+def flatnotmasked_contiguous(a):
+    """
+    Find contiguous unmasked data in a masked array.
+
+    Parameters
+    ----------
+    a : array_like
+        The input array.
+
+    Returns
+    -------
+    slice_list : list
+        A sorted sequence of `slice` objects (start index, end index).
+
+        .. versionchanged:: 1.15.0
+            Now returns an empty list instead of None for a fully masked array
+
+    See Also
+    --------
+    flatnotmasked_edges, notmasked_contiguous, notmasked_edges
+    clump_masked, clump_unmasked
+
+    Notes
+    -----
+    Only accepts 2-D arrays at most.
+
+    Examples
+    --------
+    >>> a = np.ma.arange(10)
+    >>> np.ma.flatnotmasked_contiguous(a)
+    [slice(0, 10, None)]
+
+    >>> mask = (a < 3) | (a > 8) | (a == 5)
+    >>> a[mask] = np.ma.masked
+    >>> np.array(a[~a.mask])
+    array([3, 4, 6, 7, 8])
+
+    >>> np.ma.flatnotmasked_contiguous(a)
+    [slice(3, 5, None), slice(6, 9, None)]
+    >>> a[:] = np.ma.masked
+    >>> np.ma.flatnotmasked_contiguous(a)
+    []
+
+    """
+    m = getmask(a)
+    if m is nomask:
+        return [slice(0, a.size)]
+    i = 0
+    result = []
+    for (k, g) in itertools.groupby(m.ravel()):
+        n = len(list(g))
+        if not k:
+            result.append(slice(i, i + n))
+        i += n
+    return result
+
+
+def notmasked_contiguous(a, axis=None):
+    """
+    Find contiguous unmasked data in a masked array along the given axis.
+
+    Parameters
+    ----------
+    a : array_like
+        The input array.
+    axis : int, optional
+        Axis along which to perform the operation.
+        If None (default), applies to a flattened version of the array, and this
+        is the same as `flatnotmasked_contiguous`.
+
+    Returns
+    -------
+    endpoints : list
+        A list of slices (start and end indexes) of unmasked indexes
+        in the array.
+
+        If the input is 2d and axis is specified, the result is a list of lists.
+
+    See Also
+    --------
+    flatnotmasked_edges, flatnotmasked_contiguous, notmasked_edges
+    clump_masked, clump_unmasked
+
+    Notes
+    -----
+    Only accepts 2-D arrays at most.
+
+    Examples
+    --------
+    >>> a = np.arange(12).reshape((3, 4))
+    >>> mask = np.zeros_like(a)
+    >>> mask[1:, :-1] = 1; mask[0, 1] = 1; mask[-1, 0] = 0
+    >>> ma = np.ma.array(a, mask=mask)
+    >>> ma
+    masked_array(
+      data=[[0, --, 2, 3],
+            [--, --, --, 7],
+            [8, --, --, 11]],
+      mask=[[False,  True, False, False],
+            [ True,  True,  True, False],
+            [False,  True,  True, False]],
+      fill_value=999999)
+    >>> np.array(ma[~ma.mask])
+    array([ 0,  2,  3,  7, 8, 11])
+
+    >>> np.ma.notmasked_contiguous(ma)
+    [slice(0, 1, None), slice(2, 4, None), slice(7, 9, None), slice(11, 12, None)]
+
+    >>> np.ma.notmasked_contiguous(ma, axis=0)
+    [[slice(0, 1, None), slice(2, 3, None)], [], [slice(0, 1, None)], [slice(0, 3, None)]]
+
+    >>> np.ma.notmasked_contiguous(ma, axis=1)
+    [[slice(0, 1, None), slice(2, 4, None)], [slice(3, 4, None)], [slice(0, 1, None), slice(3, 4, None)]]
+
+    """
+    a = asarray(a)
+    nd = a.ndim
+    if nd > 2:
+        raise NotImplementedError("Currently limited to at most 2D array.")
+    if axis is None or nd == 1:
+        return flatnotmasked_contiguous(a)
+    #
+    result = []
+    #
+    other = (axis + 1) % 2
+    idx = [0, 0]
+    idx[axis] = slice(None, None)
+    #
+    for i in range(a.shape[other]):
+        idx[other] = i
+        result.append(flatnotmasked_contiguous(a[tuple(idx)]))
+    return result
+
+
+def _ezclump(mask):
+    """
+    Finds the clumps (groups of data with the same values) for a 1D bool array.
+
+    Returns a series of slices.
+    """
+    if mask.ndim > 1:
+        mask = mask.ravel()
+    idx = (mask[1:] ^ mask[:-1]).nonzero()
+    idx = idx[0] + 1
+
+    if mask[0]:
+        if len(idx) == 0:
+            return [slice(0, mask.size)]
+
+        r = [slice(0, idx[0])]
+        r.extend((slice(left, right)
+                  for left, right in zip(idx[1:-1:2], idx[2::2])))
+    else:
+        if len(idx) == 0:
+            return []
+
+        r = [slice(left, right) for left, right in zip(idx[:-1:2], idx[1::2])]
+
+    if mask[-1]:
+        r.append(slice(idx[-1], mask.size))
+    return r
+
+
+def clump_unmasked(a):
+    """
+    Return list of slices corresponding to the unmasked clumps of a 1-D array.
+    (A "clump" is defined as a contiguous region of the array).
+
+    Parameters
+    ----------
+    a : ndarray
+        A one-dimensional masked array.
+
+    Returns
+    -------
+    slices : list of slice
+        The list of slices, one for each continuous region of unmasked
+        elements in `a`.
+
+    Notes
+    -----
+    .. versionadded:: 1.4.0
+
+    See Also
+    --------
+    flatnotmasked_edges, flatnotmasked_contiguous, notmasked_edges
+    notmasked_contiguous, clump_masked
+
+    Examples
+    --------
+    >>> a = np.ma.masked_array(np.arange(10))
+    >>> a[[0, 1, 2, 6, 8, 9]] = np.ma.masked
+    >>> np.ma.clump_unmasked(a)
+    [slice(3, 6, None), slice(7, 8, None)]
+
+    """
+    mask = getattr(a, '_mask', nomask)
+    if mask is nomask:
+        return [slice(0, a.size)]
+    return _ezclump(~mask)
+
+
+def clump_masked(a):
+    """
+    Returns a list of slices corresponding to the masked clumps of a 1-D array.
+    (A "clump" is defined as a contiguous region of the array).
+
+    Parameters
+    ----------
+    a : ndarray
+        A one-dimensional masked array.
+
+    Returns
+    -------
+    slices : list of slice
+        The list of slices, one for each continuous region of masked elements
+        in `a`.
+
+    Notes
+    -----
+    .. versionadded:: 1.4.0
+
+    See Also
+    --------
+    flatnotmasked_edges, flatnotmasked_contiguous, notmasked_edges
+    notmasked_contiguous, clump_unmasked
+
+    Examples
+    --------
+    >>> a = np.ma.masked_array(np.arange(10))
+    >>> a[[0, 1, 2, 6, 8, 9]] = np.ma.masked
+    >>> np.ma.clump_masked(a)
+    [slice(0, 3, None), slice(6, 7, None), slice(8, 10, None)]
+
+    """
+    mask = ma.getmask(a)
+    if mask is nomask:
+        return []
+    return _ezclump(mask)
+
+
+###############################################################################
+#                              Polynomial fit                                 #
+###############################################################################
+
+
+def vander(x, n=None):
+    """
+    Masked values in the input array result in rows of zeros.
+
+    """
+    _vander = np.vander(x, n)
+    m = getmask(x)
+    if m is not nomask:
+        _vander[m] = 0
+    return _vander
+
+vander.__doc__ = ma.doc_note(np.vander.__doc__, vander.__doc__)
+
+
+def polyfit(x, y, deg, rcond=None, full=False, w=None, cov=False):
+    """
+    Any masked values in x is propagated in y, and vice-versa.
+
+    """
+    x = asarray(x)
+    y = asarray(y)
+
+    m = getmask(x)
+    if y.ndim == 1:
+        m = mask_or(m, getmask(y))
+    elif y.ndim == 2:
+        my = getmask(mask_rows(y))
+        if my is not nomask:
+            m = mask_or(m, my[:, 0])
+    else:
+        raise TypeError("Expected a 1D or 2D array for y!")
+
+    if w is not None:
+        w = asarray(w)
+        if w.ndim != 1:
+            raise TypeError("expected a 1-d array for weights")
+        if w.shape[0] != y.shape[0]:
+            raise TypeError("expected w and y to have the same length")
+        m = mask_or(m, getmask(w))
+
+    if m is not nomask:
+        not_m = ~m
+        if w is not None:
+            w = w[not_m]
+        return np.polyfit(x[not_m], y[not_m], deg, rcond, full, w, cov)
+    else:
+        return np.polyfit(x, y, deg, rcond, full, w, cov)
+
+polyfit.__doc__ = ma.doc_note(np.polyfit.__doc__, polyfit.__doc__)