Log message:
py-xarray: updated to 0.20.2

v0.20.2

This is a bugfix release to resolve (:issue:`3391`, :issue:`5715`). It also
includes performance improvements in unstacking to a ``sparse`` array and a
number of documentation improvements.

Breaking changes
- Use complex nan when interpolating complex values out of bounds by default \ 
(instead of real nan) (:pull:`6019`).

Performance
- Significantly faster unstacking to a ``sparse`` array. :pull:`5577`

Bug fixes
- :py:func:`xr.map_blocks` and :py:func:`xr.corr` now work when dask is not \ 
installed (:issue:`3391`, :issue:`5715`, :pull:`5731`).
- Fix plot.line crash for data of shape ``(1, N)`` in _title_for_slice on \ 
format_item (:pull:`5948`).
- Fix a regression in the removal of duplicate backend entrypoints \ 
(:issue:`5944`, :pull:`5959`)

Documentation
- Better examples in docstrings for groupby and resampling reductions (:pull:`5871`).

Internal Changes
- Use ``importlib`` to replace functionality of ``pkg_resources`` in
  backend plugins tests. (:pull:`5959`).

Log message:
py-xarray: updated to 0.20.1

v0.20.1 (5 November 2021)
-------------------------

This is a bugfix release to fix :issue:`5930`.

Bug fixes
~~~~~~~~~
- Fix a regression in the detection of the backend entrypoints (:issue:`5930`, \ 
:pull:`5931`)
  By `Justus Magin <https://github.com/keewis>`_.

Documentation
~~~~~~~~~~~~~

- Significant improvements to  :ref:`api`. By `Deepak Cherian \ 
<https://github.com/dcherian>`_.

.. _whats-new.0.20.0:

v0.20.0 (1 November 2021)
-------------------------

This release brings improved support for pint arrays, methods for weighted \ 
standard deviation, variance,
and sum of squares, the option to disable the use of the bottleneck library, \ 
significantly improved performance of
unstack, as well as many bugfixes and internal changes.

Many thanks to the 40 contributors to this release!:

Aaron Spring, Akio Taniguchi, Alan D. Snow, arfy slowy, Benoit Bovy, Christian \ 
Jauvin, crusaderky, Deepak Cherian,
Giacomo Caria, Illviljan, James Bourbeau, Joe Hamman, Joseph K Aicher, Julien \ 
Herzen, Kai Mühlbauer,
keewis, lusewell, Martin K. Scherer, Mathias Hauser, Max Grover, Maxime Liquet, \ 
Maximilian Roos, Mike Taves, Nathan Lis,
pmav99, Pushkar Kopparla, Ray Bell, Rio McMahon, Scott Staniewicz, Spencer \ 
Clark, Stefan Bender, Taher Chegini,
Thomas Nicholas, Tomas Chor, Tom Augspurger, Victor Negîrneac, Zachary \ 
Blackwood, Zachary Moon, and Zeb Nicholls.

New Features
~~~~~~~~~~~~
- Add ``std``, ``var``,  ``sum_of_squares`` to \ 
:py:class:`~core.weighted.DatasetWeighted` and \ 
:py:class:`~core.weighted.DataArrayWeighted`.
  By `Christian Jauvin <https://github.com/cjauvin>`_.
- Added a :py:func:`get_options` method to xarray's root namespace \ 
(:issue:`5698`, :pull:`5716`)
  By `Pushkar Kopparla <https://github.com/pkopparla>`_.
- Xarray now does a better job rendering variable names that are long LaTeX \ 
sequences when plotting (:issue:`5681`, :pull:`5682`).
  By `Tomas Chor <https://github.com/tomchor>`_.
- Add an option (``"use_bottleneck"``) to disable the use of \ 
``bottleneck`` using :py:func:`set_options` (:pull:`5560`)
  By `Justus Magin <https://github.com/keewis>`_.
- Added ``**kwargs`` argument to :py:meth:`open_rasterio` to access overviews \ 
(:issue:`3269`).
  By `Pushkar Kopparla <https://github.com/pkopparla>`_.
- Added ``storage_options`` argument to :py:meth:`to_zarr` (:issue:`5601`, \ 
:pull:`5615`).
  By `Ray Bell <https://github.com/raybellwaves>`_, `Zachary Blackwood \ 
<https://github.com/blackary>`_ and
  `Nathan Lis <https://github.com/wxman22>`_.
- Histogram plots are set with a title displaying the scalar coords if any, \ 
similarly to the other plots (:issue:`5791`, :pull:`5792`).
  By `Maxime Liquet <https://github.com/maximlt>`_.
- Slice plots display the coords units in the same way as x/y/colorbar labels \ 
(:pull:`5847`).
  By `Victor Negîrneac <https://github.com/caenrigen>`_.
- Added a new :py:attr:`Dataset.chunksizes`, :py:attr:`DataArray.chunksizes`, \ 
and :py:attr:`Variable.chunksizes`
  property, which will always return a mapping from dimension names to chunking \ 
pattern along that dimension,
  regardless of whether the object is a Dataset, DataArray, or Variable. \ 
(:issue:`5846`, :pull:`5900`)
  By `Tom Nicholas <https://github.com/TomNicholas>`_.

Breaking changes
~~~~~~~~~~~~~~~~
- The minimum versions of some dependencies were changed:

  =============== ====== ====
  Package         Old    New
  =============== ====== ====
  cftime          1.1    1.2
  dask            2.15   2.30
  distributed     2.15   2.30
  lxml            4.5    4.6
  matplotlib-base 3.2    3.3
  numba           0.49   0.51
  numpy           1.17   1.18
  pandas          1.0    1.1
  pint            0.15   0.16
  scipy           1.4    1.5
  seaborn         0.10   0.11
  sparse          0.8    0.11
  toolz           0.10   0.11
  zarr            2.4    2.5
  =============== ====== ====

- The ``__repr__`` of a :py:class:`xarray.Dataset`'s ``coords`` and ``data_vars``
  ignore ``xarray.set_option(display_max_rows=...)`` and show the full output
  when called directly as, e.g., ``ds.data_vars`` or ``print(ds.data_vars)``
  (:issue:`5545`, :pull:`5580`).
  By `Stefan Bender <https://github.com/st-bender>`_.

Deprecations
~~~~~~~~~~~~

- Deprecate :py:func:`open_rasterio` (:issue:`4697`, :pull:`5808`).
  By `Alan Snow <https://github.com/snowman2>`_.
- Set the default argument for `roll_coords` to `False` for :py:meth:`DataArray.roll`
  and :py:meth:`Dataset.roll`. (:pull:`5653`)
  By `Tom Nicholas <https://github.com/TomNicholas>`_.
- :py:meth:`xarray.open_mfdataset` will now error instead of warn when a value \ 
for ``concat_dim`` is
  passed alongside ``combine='by_coords'``.
  By `Tom Nicholas <https://github.com/TomNicholas>`_.

Bug fixes
~~~~~~~~~

- Fix ZeroDivisionError from saving dask array with empty dimension (:issue: `5741`).
  By `Joseph K Aicher <https://github.com/jaicher>`_.
- Fixed performance bug where ``cftime`` import attempted within various core \ 
operations if ``cftime`` not
  installed (:pull:`5640`).
  By `Luke Sewell <https://github.com/lusewell>`_
- Fixed bug when combining named DataArrays using :py:func:`combine_by_coords`. \ 
(:pull:`5834`).
  By `Tom Nicholas <https://github.com/TomNicholas>`_.
- When a custom engine was used in :py:func:`~xarray.open_dataset` the engine
  wasn't initialized properly, causing missing argument errors or inconsistent
  method signatures. (:pull:`5684`)
  By `Jimmy Westling <https://github.com/illviljan>`_.
- Numbers are properly formatted in a plot's title (:issue:`5788`, :pull:`5789`).
  By `Maxime Liquet <https://github.com/maximlt>`_.
- Faceted plots will no longer raise a `pint.UnitStrippedWarning` when a \ 
`pint.Quantity` array is plotted,
  and will correctly display the units of the data in the colorbar (if there is \ 
one) (:pull:`5886`).
  By `Tom Nicholas <https://github.com/TomNicholas>`_.
- With backends, check for path-like objects rather than ``pathlib.Path``
  type, use ``os.fspath`` (:pull:`5879`).
  By `Mike Taves <https://github.com/mwtoews>`_.
- ``open_mfdataset()`` now accepts a single ``pathlib.Path`` object (:issue: `5881`).
  By `Panos Mavrogiorgos <https://github.com/pmav99>`_.
- Improved performance of :py:meth:`Dataset.unstack` (:pull:`5906`). By `Tom \ 
Augspurger <https://github.com/TomAugspurger>`_.

Documentation
~~~~~~~~~~~~~

- Users are instructed to try ``use_cftime=True`` if a ``TypeError`` occurs when \ 
combining datasets and one of the types involved is a subclass of \ 
``cftime.datetime`` (:pull:`5776`).
  By `Zeb Nicholls <https://github.com/znicholls>`_.
- A clearer error is now raised if a user attempts to assign a Dataset to a \ 
single key of
  another Dataset. (:pull:`5839`)
  By `Tom Nicholas <https://github.com/TomNicholas>`_.

Internal Changes
~~~~~~~~~~~~~~~~

- Explicit indexes refactor: avoid ``len(index)`` in ``map_blocks`` (:pull:`5670`).
  By `Deepak Cherian <https://github.com/dcherian>`_.
- Explicit indexes refactor: decouple ``xarray.Index``` from ``xarray.Variable`` \ 
(:pull:`5636`).
  By `Benoit Bovy <https://github.com/benbovy>`_.
- Fix ``Mapping`` argument typing to allow mypy to pass on ``str`` keys \ 
(:pull:`5690`).
  By `Maximilian Roos <https://github.com/max-sixty>`_.
- Annotate many of our tests, and fix some of the resulting typing errors. This will
  also mean our typing annotations are tested as part of CI. (:pull:`5728`).
  By `Maximilian Roos <https://github.com/max-sixty>`_.
- Improve the performance of reprs for large datasets or dataarrays. (:pull:`5661`)
  By `Jimmy Westling <https://github.com/illviljan>`_.
- Use isort's `float_to_top` config. (:pull:`5695`).
  By `Maximilian Roos <https://github.com/max-sixty>`_.
- Remove use of the deprecated ``kind`` argument in
  :py:meth:`pandas.Index.get_slice_bound` inside :py:class:`xarray.CFTimeIndex`
  tests (:pull:`5723`).  By `Spencer Clark \ 
<https://github.com/spencerkclark>`_.
- Refactor `xarray.core.duck_array_ops` to no longer special-case dispatching to
  dask versions of functions when acting on dask arrays, instead relying numpy
  and dask's adherence to NEP-18 to dispatch automatically. (:pull:`5571`)
  By `Tom Nicholas <https://github.com/TomNicholas>`_.
- Add an ASV benchmark CI and improve performance of the benchmarks (:pull:`5796`)
  By `Jimmy Westling <https://github.com/illviljan>`_.
- Use ``importlib`` to replace functionality of ``pkg_resources`` such
  as version setting and loading of resources. (:pull:`5845`).
  By `Martin K. Scherer <https://github.com/marscher>`_.

.. _whats-new.0.19.0:

v0.19.0 (23 July 2021)
----------------------

This release brings improvements to plotting of categorical data, the ability to \ 
specify how attributes
are combined in xarray operations, a new high-level :py:func:`unify_chunks` \ 
function, as well as various
deprecations, bug fixes, and minor improvements.

Many thanks to the 29 contributors to this release!:

Andrew Williams, Augustus, Aureliana Barghini, Benoit Bovy, crusaderky, Deepak \ 
Cherian, ellesmith88,
Elliott Sales de Andrade, Giacomo Caria, github-actions[bot], Illviljan, \ 
Joeperdefloep, joooeey, Julia Kent,
Julius Busecke, keewis, Mathias Hauser, Matthias Göbel, Mattia Almansi, \ 
Maximilian Roos, Peter Andreas Entschev,
Ray Bell, Sander, Santiago Soler, Sebastian, Spencer Clark, Stephan Hoyer, \ 
Thomas Hirtz, Thomas Nicholas.

New Features
~~~~~~~~~~~~
- Allow passing argument ``missing_dims`` to :py:meth:`Variable.transpose` and \ 
:py:meth:`Dataset.transpose`
  (:issue:`5550`, :pull:`5586`)
  By `Giacomo Caria <https://github.com/gcaria>`_.
- Allow passing a dictionary as coords to a :py:class:`DataArray` (:issue:`5527`,
  reverts :pull:`1539`, which had deprecated this due to python's inconsistent \ 
ordering in earlier versions).
  By `Sander van Rijn <https://github.com/sjvrijn>`_.
- Added :py:meth:`Dataset.coarsen.construct`, \ 
:py:meth:`DataArray.coarsen.construct` (:issue:`5454`, :pull:`5475`).
  By `Deepak Cherian <https://github.com/dcherian>`_.
- Xarray now uses consolidated metadata by default when writing and reading Zarr
  stores (:issue:`5251`).
  By `Stephan Hoyer <https://github.com/shoyer>`_.
- New top-level function :py:func:`unify_chunks`.
  By `Mattia Almansi <https://github.com/malmans2>`_.
- Allow assigning values to a subset of a dataset using positional or label-based
  indexing (:issue:`3015`, :pull:`5362`).
  By `Matthias Göbel <https://github.com/matzegoebel>`_.
- Attempting to reduce a weighted object over missing dimensions now raises an \ 
error (:pull:`5362`).
  By `Mattia Almansi <https://github.com/malmans2>`_.
- Add ``.sum`` to :py:meth:`~xarray.DataArray.rolling_exp` and
  :py:meth:`~xarray.Dataset.rolling_exp` for exponentially weighted rolling
  sums. These require numbagg 0.2.1;
  (:pull:`5178`).
  By `Maximilian Roos <https://github.com/max-sixty>`_.
- :py:func:`xarray.cov` and :py:func:`xarray.corr` now lazily check for missing
  values if inputs are dask arrays (:issue:`4804`, :pull:`5284`).
  By `Andrew Williams <https://github.com/AndrewWilliams3142>`_.
- Attempting to ``concat`` list of elements that are not all ``Dataset`` or all \ 
``DataArray`` now raises an error (:issue:`5051`, :pull:`5425`).
  By `Thomas Hirtz <https://github.com/thomashirtz>`_.
- allow passing a function to ``combine_attrs`` (:pull:`4896`).
  By `Justus Magin <https://github.com/keewis>`_.
- Allow plotting categorical data (:pull:`5464`).
  By `Jimmy Westling <https://github.com/illviljan>`_.
- Allow removal of the coordinate attribute ``coordinates`` on variables by \ 
setting ``.attrs['coordinates']= None``
  (:issue:`5510`).
  By `Elle Smith <https://github.com/ellesmith88>`_.
- Added :py:meth:`DataArray.to_numpy`, :py:meth:`DataArray.as_numpy`, and \ 
:py:meth:`Dataset.as_numpy`. (:pull:`5568`).
  By `Tom Nicholas <https://github.com/TomNicholas>`_.
- Units in plot labels are now automatically inferred from wrapped \ 
:py:meth:`pint.Quantity` arrays. (:pull:`5561`).
  By `Tom Nicholas <https://github.com/TomNicholas>`_.

Breaking changes
~~~~~~~~~~~~~~~~

- The default ``mode`` for :py:meth:`Dataset.to_zarr` when ``region`` is set
  has changed to the new ``mode="r+"``, which only allows for overriding
  pre-existing array values. This is a safer default than the prior \ 
``mode="a"``,
  and allows for higher performance writes (:pull:`5252`).
  By `Stephan Hoyer <https://github.com/shoyer>`_.
- The main parameter to :py:func:`combine_by_coords` is renamed to \ 
`data_objects` instead
  of `datasets` so anyone calling this method using a named parameter will need \ 
to update
  the name accordingly (:issue:`3248`, :pull:`4696`).
  By `Augustus Ijams <https://github.com/aijams>`_.

Deprecations
~~~~~~~~~~~~

- Removed the deprecated ``dim`` kwarg to :py:func:`DataArray.integrate` \ 
(:pull:`5630`)
- Removed the deprecated ``keep_attrs`` kwarg to :py:func:`DataArray.rolling` \ 
(:pull:`5630`)
- Removed the deprecated ``keep_attrs`` kwarg to :py:func:`DataArray.coarsen` \ 
(:pull:`5630`)
- Completed deprecation of passing an ``xarray.DataArray`` to \ 
:py:func:`Variable` - will now raise a ``TypeError`` (:pull:`5630`)

Bug fixes
~~~~~~~~~
- Fix a minor incompatibility between partial datetime string indexing with a
  :py:class:`CFTimeIndex` and upcoming pandas version 1.3.0 (:issue:`5356`,
  :pull:`5359`).
  By `Spencer Clark <https://github.com/spencerkclark>`_.
- Fix 1-level multi-index incorrectly converted to single index (:issue:`5384`,
  :pull:`5385`).
  By `Benoit Bovy <https://github.com/benbovy>`_.
- Don't cast a duck array in a coordinate to :py:class:`numpy.ndarray` in
  :py:meth:`DataArray.differentiate` (:pull:`5408`)
  By `Justus Magin <https://github.com/keewis>`_.
- Fix the ``repr`` of :py:class:`Variable` objects with ``display_expand_data=True``
  (:pull:`5406`)
  By `Justus Magin <https://github.com/keewis>`_.
- Plotting a pcolormesh with ``xscale="log"`` and/or \ 
``yscale="log"`` works as
  expected after improving the way the interval breaks are generated (:issue:`5333`).
  By `Santiago Soler <https://github.com/santisoler>`_
- :py:func:`combine_by_coords` can now handle combining a list of unnamed
  ``DataArray`` as input (:issue:`3248`, :pull:`4696`).
  By `Augustus Ijams <https://github.com/aijams>`_.

Internal Changes
~~~~~~~~~~~~~~~~
- Run CI on the first & last python versions supported only; currently 3.7 \ 
& 3.9.
  (:pull:`5433`)
  By `Maximilian Roos <https://github.com/max-sixty>`_.
- Publish test results & timings on each PR.
  (:pull:`5537`)
  By `Maximilian Roos <https://github.com/max-sixty>`_.
- Explicit indexes refactor: add a ``xarray.Index.query()`` method in which
  one may eventually provide a custom implementation of label-based data
  selection (not ready yet for public use). Also refactor the internal,
  pandas-specific implementation into ``PandasIndex.query()`` and
  ``PandasMultiIndex.query()`` (:pull:`5322`).
  By `Benoit Bovy <https://github.com/benbovy>`_.

Log message:
math: Replace RMD160 checksums with BLAKE2s checksums

All checksums have been double-checked against existing RMD160 and
SHA512 hashes

Log message:
math: Remove SHA1 hashes for distfiles

Log message:
py-xarray: updated to 0.18.2

v0.18.2 (19 May 2021)
---------------------
This release reverts a regression in xarray's unstacking of dask-backed arrays.

v0.18.1 (18 May 2021)
---------------------
This release is intended as a small patch release to be compatible with the new
2021.5.0 ``dask.distributed`` release. It also includes a new
``drop_duplicates`` method, some documentation improvements, the beginnings of
our internal Index refactoring, and some bug fixes.

New Features

- Implement :py:meth:`DataArray.drop_duplicates`
  to remove duplicate dimension values (:pull:`5239`).
- Allow passing ``combine_attrs`` strategy names to the ``keep_attrs`` parameter of
  :py:func:`apply_ufunc` (:pull:`5041`)
- :py:meth:`Dataset.interp` now allows interpolation with non-numerical datatypes,
  such as booleans, instead of dropping them. (:issue:`4761` :pull:`5008`).
- Raise more informative error when decoding time variables with invalid \ 
reference dates.
  (:issue:`5199`, :pull:`5288`).

Bug fixes

- Opening netCDF files from a path that doesn't end in ``.nc`` without supplying
  an explicit ``engine`` works again (:issue:`5295`), fixing a bug introduced in
  0.18.0.

Documentation

- Clean up and enhance docstrings for the :py:class:`DataArray.plot` and \ 
``Dataset.plot.*``
  families of methods (:pull:`5285`).

- Explanation of deprecation cycles and how to implement them added to contributors
  guide. (:pull:`5289`)

Log message:
py-xarray: updated to 0.18.0

v0.18.0 (6 May 2021)

This release brings a few important performance improvements, a wide range of \ 
usability upgrades, lots of bug fixes, and some new features. These include a \ 
plugin API to add backend engines, a new theme for the documentation, curve \ 
fitting methods, and several new plotting functions.

v0.17.0 (24 Feb 2021)

This release brings a few important performance improvements, a wide range of \ 
usability upgrades, lots of bug fixes, and some new features. These include \ 
better cftime support, a new quiver plot, better unstack performance, more \ 
efficient memory use in rolling operations, and some python packaging \ 
improvements. We also have a few documentation improvements (and more planned!).

v0.16.2 (30 Nov 2020)

This release brings the ability to write to limited regions of zarr files, open \ 
zarr files with :py:func:`open_dataset` and :py:func:`open_mfdataset`, increased \ 
support for propagating attrs using the keep_attrs flag, as well as numerous \ 
bugfixes and documentation improvements.

v0.16.1 (2020-09-20)

This patch release fixes an incompatibility with a recent pandas change, which \ 
was causing an issue indexing with a datetime64. It also includes improvements \ 
to rolling, to_dataframe, cov & corr methods and bug fixes. Our \ 
documentation has a number of improvements, including fixing all doctests and \ 
confirming their accuracy on every commit.

v0.16.0 (2020-07-11)

This release adds xarray.cov & xarray.corr for covariance & correlation \ 
respectively; the idxmax & idxmin methods, the polyfit method & \ 
xarray.polyval for fitting polynomials, as well as a number of documentation \ 
improvements, other features, and bug fixes. Many thanks to all 44 contributors \ 
who contributed to this release:

Log message:
propagate python incompatibilities

Log message:
*: switch to versioned_dependencies.mk for py-setuptools

Log message:
Needs py-pip and py-setuptools_scm

Log message:
py-xarray: updated to 0.15.1

v0.15.1:
This release brings many new features such as :py:meth:`Dataset.weighted` \ 
methods for weighted array
reductions, a new jupyter repr by default, and the start of units integration \ 
with pint. There's also
the usual batch of usability improvements, documentation additions, and bug fixes.

Breaking changes
- Raise an error when assigning to the ``.values`` or ``.data`` attribute of
  dimension coordinates i.e. ``IndexVariable`` objects. This has been broken since
  v0.12.0. Please use :py:meth:`DataArray.assign_coords` or \ 
:py:meth:`Dataset.assign_coords`
  instead.

New Features
- Weighted array reductions are now supported via the new \ 
:py:meth:`DataArray.weighted`
  and :py:meth:`Dataset.weighted` methods. See :ref:`comput.weighted`.
- The new jupyter notebook repr (``Dataset._repr_html_`` and
  ``DataArray._repr_html_``) (introduced in 0.14.1) is now on by default. To
  disable, use ``xarray.set_options(display_style="text")``.
- Added support for :py:class:`pandas.DatetimeIndex`-style rounding of
  ``cftime.datetime`` objects directly via a :py:class:`CFTimeIndex` or via the
  :py:class:`~core.accessor_dt.DatetimeAccessor`.
- Support new h5netcdf backend keyword `phony_dims` (available from h5netcdf
  v0.8.0 for :py:class:`~xarray.backends.H5NetCDFStore`.
- Add partial support for unit aware arrays with pint.
- :py:meth:`Dataset.groupby` and :py:meth:`DataArray.groupby` now raise a
  `TypeError` on multiple string arguments. Receiving multiple string arguments
  often means a user is attempting to pass multiple dimensions as separate
  arguments and should instead pass a single list of dimensions.
- :py:func:`map_blocks` can now apply functions that add new unindexed dimensions.
- An ellipsis (``...``) is now supported in the ``dims`` argument of
  :py:meth:`Dataset.stack` and :py:meth:`DataArray.stack`, meaning all
  unlisted dimensions, similar to its meaning in :py:meth:`DataArray.transpose`.
- :py:meth:`Dataset.where` and :py:meth:`DataArray.where` accept a lambda as a
  first argument, which is then called on the input; replicating pandas' behavior.
- ``skipna`` is available in :py:meth:`Dataset.quantile`, \ 
:py:meth:`DataArray.quantile`,
  :py:meth:`core.groupby.DatasetGroupBy.quantile`, \ 
:py:meth:`core.groupby.DataArrayGroupBy.quantile`

Bug fixes
- Fix :py:meth:`Dataset.interp` when indexing array shares coordinates with the
  indexed variable
- Fix recombination of groups in :py:meth:`Dataset.groupby` and
  :py:meth:`DataArray.groupby` when performing an operation that changes the
  size of the groups along the grouped dimension. By `Eric Jansen
  <https://github.com/ej81>`_.
- Fix use of multi-index with categorical values
- Fix alignment with ``join="override"`` when some dimensions are \ 
unindexed.
- Fix :py:meth:`Dataset.swap_dims` and :py:meth:`DataArray.swap_dims` producing
  index with name reflecting the previous dimension name instead of the new one
- Use ``dask_array_type`` instead of ``dask_array.Array`` for type
  checking.
- :py:func:`concat` can now handle coordinate variables only present in one of
  the objects to be concatenated when ``coords="different"``.
- xarray now respects the over, under and bad colors if set on a provided colormap.
- :py:func:`coarsen` now respects ``xr.set_options(keep_attrs=True)``
  to preserve attributes. :py:meth:`Dataset.coarsen` accepts a keyword
  argument ``keep_attrs`` to change this setting.
  :pull:`3801`) By `Andrew Thomas <https://github.com/amcnicho>`_.
- Delete associated indexes when deleting coordinate variables.
- Fix :py:meth:`xarray.core.dataset.Dataset.to_zarr` when using `append_dim` and \ 
`group`
  simultaneously.
- Fix html repr on :py:class:`Dataset` with non-string keys

Documentation
- Fix documentation of :py:class:`DataArray` removing the deprecated mention
  that when omitted, `dims` are inferred from a `coords`-dict.
- Improve the :py:func:`where` docstring.
- Update the installation instructions: only explicitly list recommended dependencies

Internal Changes
- Remove the internal ``import_seaborn`` function which handled the deprecation of
  the ``seaborn.apionly`` entry point
- Don't test pint integration in combination with datetime objects.
- Change test_open_mfdataset_list_attr to only run with dask installed
- Preserve the ability to index with ``method="nearest"`` with a
  :py:class:`CFTimeIndex` with pandas versions greater than 1.0.1
- Greater flexibility and improved test coverage of subtracting various types
  of objects from a :py:class:`CFTimeIndex`. By `Spencer Clark
  <https://github.com/spencerkclark>`_.
- Update Azure CI MacOS image, given pending removal.
- Remove xfails for scipy 1.0.1 for tests that append to netCDF files
- Remove conversion to :py:class:`pandas.Panel`, given its removal in pandas
  in favor of xarray's objects.

v0.15.0:
This release brings many improvements to xarray's documentation: our examples \ 
are now binderized notebooks (`click here \ 
<https://mybinder.org/v2/gh/pydata/xarray/master?urlpath=lab/tree/doc/examples/weather-data.ipynb>`_)
and we have new example notebooks from our SciPy 2019 sprint (many thanks to our \ 
contributors!).

This release also features many API improvements such as a new
:py:class:`~core.accessor_dt.TimedeltaAccessor` and support for \ 
:py:class:`CFTimeIndex` in
:py:meth:`~DataArray.interpolate_na`); as well as many bug fixes.

Breaking changes
- Bumped minimum tested versions for dependencies:
  - numpy 1.15
  - pandas 0.25
  - dask 2.2
  - distributed 2.2
  - scipy 1.3

- Remove ``compat`` and ``encoding`` kwargs from ``DataArray``, which
  have been deprecated since 0.12.
  Instead, specify the ``encoding`` kwarg when writing to disk or set
  the :py:attr:`DataArray.encoding` attribute directly.
- :py:func:`xarray.dot`, :py:meth:`DataArray.dot`, and the ``@`` operator now
  use ``align="inner"`` (except when \ 
``xarray.set_options(arithmetic_join="exact")``;

New Features
- Implement :py:meth:`DataArray.pad` and :py:meth:`Dataset.pad`.
- :py:meth:`DataArray.sel` and :py:meth:`Dataset.sel` now support \ 
:py:class:`pandas.CategoricalIndex`.
- Support using an existing, opened h5netcdf ``File`` with
  :py:class:`~xarray.backends.H5NetCDFStore`. This permits creating an
  :py:class:`~xarray.Dataset` from a h5netcdf ``File`` that has been opened
  using other means
- Implement ``median`` and ``nanmedian`` for dask arrays. This works by rechunking
  to a single chunk along all reduction axes.
- :py:func:`~xarray.concat` now preserves attributes from the first Variable.
- :py:meth:`Dataset.quantile`, :py:meth:`DataArray.quantile` and ``GroupBy.quantile``
  now work with dask Variables.
- Added the ``count`` reduction method to both \ 
:py:class:`~core.rolling.DatasetCoarsen`
  and :py:class:`~core.rolling.DataArrayCoarsen` objects.
- Add ``meta`` kwarg to :py:func:`~xarray.apply_ufunc`;
  this is passed on to :py:func:`dask.array.blockwise`.
- Add ``attrs_file`` option in :py:func:`~xarray.open_mfdataset` to choose the
  source file for global attributes in a multi-file dataset
  :pull:`3498`). By `Julien Seguinot <https://github.com/juseg>`_.
- :py:meth:`Dataset.swap_dims` and :py:meth:`DataArray.swap_dims`
  now allow swapping to dimension names that don't exist yet.
- Extend :py:class:`~core.accessor_dt.DatetimeAccessor` properties
  and support ``.dt`` accessor for timedeltas
  via :py:class:`~core.accessor_dt.TimedeltaAccessor`
- Improvements to interpolating along time axes
  - Support :py:class:`CFTimeIndex` in :py:meth:`DataArray.interpolate_na`
  - define 1970-01-01 as the default offset for the interpolation index for both
    :py:class:`pandas.DatetimeIndex` and :py:class:`CFTimeIndex`,
  - use microseconds in the conversion from timedelta objects to floats to avoid
    overflow errors.

Bug fixes
- Applying a user-defined function that adds new dimensions using \ 
:py:func:`apply_ufunc`
  and ``vectorize=True`` now works with ``dask > 2.0``.
- Fix :py:meth:`~xarray.combine_by_coords` to allow for combining incomplete
  hypercubes of Datasets
- Fix :py:func:`~xarray.combine_by_coords` when combining cftime coordinates
  which span long time intervals
- Fix plotting with transposed 2D non-dimensional coordinates.
- :py:meth:`plot.FacetGrid.set_titles` can now replace existing row titles of a
  :py:class:`~xarray.plot.FacetGrid` plot. In addition \ 
:py:class:`~xarray.plot.FacetGrid` gained
  two new attributes: :py:attr:`~xarray.plot.FacetGrid.col_labels` and
  :py:attr:`~xarray.plot.FacetGrid.row_labels` contain \ 
:py:class:`matplotlib.text.Text` handles for both column and
  row labels. These can be used to manually change the labels.
- Fix issue with Dask-backed datasets raising a ``KeyError`` on some \ 
computations involving :py:func:`map_blocks`
- Ensure :py:meth:`Dataset.quantile`, :py:meth:`DataArray.quantile` issue the \ 
correct error
  when ``q`` is out of bounds
- Fix regression in xarray 0.14.1 that prevented encoding times with certain
  ``dtype``, ``_FillValue``, and ``missing_value`` encodings
- Raise an error when trying to use :py:meth:`Dataset.rename_dims` to
  rename to an existing name
- :py:meth:`Dataset.rename`, :py:meth:`DataArray.rename` now check for conflicts with
  MultiIndex level names.
- :py:meth:`Dataset.merge` no longer fails when passed a :py:class:`DataArray` \ 
instead of a :py:class:`Dataset`.
- Fix a regression in :py:meth:`Dataset.drop`: allow passing any
  iterable when dropping variables
- Fixed errors emitted by ``mypy --strict`` in modules that import xarray.
- Allow plotting of binned coordinates on the y axis in :py:meth:`plot.line`
  and :py:meth:`plot.step` plots
- setuptools is now marked as a dependency of xarray

Documentation
- Switch doc examples to use `nbsphinx <https://nbsphinx.readthedocs.io>`_ \ 
and replace
  ``sphinx_gallery`` scripts with Jupyter notebooks.
- Added :doc:`example notebook <examples/ROMS_ocean_model>` demonstrating \ 
use of xarray with
  Regional Ocean Modeling System (ROMS) ocean hydrodynamic model output.
- Added :doc:`example notebook <examples/ERA5-GRIB-example>` demonstrating \ 
the visualization of
  ERA5 GRIB data.
  `Stephan Siemen <https://github.com/StephanSiemen>`_.
- Added examples for :py:meth:`DataArray.quantile`, :py:meth:`Dataset.quantile` and
  ``GroupBy.quantile``.
- Add new :doc:`example notebook <examples/apply_ufunc_vectorize_1d>` \ 
example notebook demonstrating
  vectorization of a 1D function using :py:func:`apply_ufunc` , dask and numba.
- Added example for :py:func:`~xarray.map_blocks`.

Internal Changes
- Make sure dask names change when rechunking by different chunk sizes. \ 
Conversely, make sure they
  stay the same when rechunking by the same chunk size.
- 2x to 5x speed boost (on small arrays) for :py:meth:`Dataset.isel`,
  :py:meth:`DataArray.isel`, and :py:meth:`DataArray.__getitem__` when indexing \ 
by int,
  slice, list of int, scalar ndarray, or 1-dimensional ndarray.
- Removed internal method ``Dataset._from_vars_and_coord_names``,
  which was dominated by ``Dataset._construct_direct``.
- Replaced versioneer with setuptools-scm. Moved contents of setup.py to setup.cfg.
  Removed pytest-runner from setup.py, as per deprecation notice on the pytest-runner
  project.
- Use of isort is now enforced by CI.