Datashader

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This release has been nearly a year in the making, with major new contributions from Ian Thomas, Thuy Do Thi Minh, Simon Høxbro Hansen, Maxime Liquet, and James Bednar, and additional support from Andrii Oriekhov, Philipp Rudiger, and Ajay Thorve.

Enhancements:

- Full support for `antialiased lines <https://datashader.org/user_guide/Timeseries.html#antialiasing>`_ of specified width (`1048 <https://github.com/holoviz/datashader/pull/1048>`_, `#1072 <https://github.com/holoviz/datashader/pull/1072>`_). Previous antialiasing support was limited to single-pixel lines and certain floating-point reduction functions. Now supports arbitrary widths and arbitrary reduction functions, making antialiasing fully supported. Performance ranges from 1.3x to 14x slower than the simplest zero-width implementation; see `benchmarks <https://github.com/holoviz/datashader/pull/1072>`_.
- Fixed an issue with visibility on zoomed-in points plots and on overlapping line plots that was first reported in 2017, with a new option ``rescale_discrete_levels`` for ``how='eq_hist'`` (`1055 <https://github.com/holoviz/datashader/pull/1055>`_)
- Added a `categorical color_key for 2D <https://datashader.org/getting_started/Pipeline.html#colormapping-2d-categorical-data>`_ (unstacked) aggregates (`1020 <https://github.com/holoviz/datashader/pull/1020>`_), for producing plots where each pixel has at most one category value
- Improved docs:

* A brand new `polygons guide <https://datashader.org/user_guide/Polygons.html>`_ (`#1071 <https://github.com/holoviz/datashader/pull/1071>`_)
* A new guide to `3D aggregations <https://datashader.org/getting_started/Pipeline.html#id1>`_ using ``by`` now documenting using ``categorizer`` objects to do 3D numerical binning (`1071 <https://github.com/holoviz/datashader/pull/1071>`_)
* Moved documentation for `spreading <https://datashader.org/getting_started/Pipeline.html#spreading>`_ to its own section so it can be presented at the right pipeline stage (was mixed up with colormapping before) (`1071 <https://github.com/holoviz/datashader/pull/1071>`_)
* Added `rescale_discrete_levels example <https://datashader.org/getting_started/Pipeline.html#transforming-data-values-for-colormapping>`_ (`1071 <https://github.com/holoviz/datashader/pull/1071>`_)
* Other misc doc cleanup (`1035 <https://github.com/holoviz/datashader/pull/1035>`_, `#1037 <https://github.com/holoviz/datashader/pull/1037>`_, `#1058 <https://github.com/holoviz/datashader/pull/1058>`_, `#1074 <https://github.com/holoviz/datashader/pull/1074>`_, `#1077 <https://github.com/holoviz/datashader/pull/1077>`_)

Bugfixes:

- Fixed details of the raster coordinate calculations to match other primitives, making it simpler to overlay separately rendered results (`959 <https://github.com/holoviz/datashader/pull/959>`_, `#1046 <https://github.com/holoviz/datashader/pull/1046>`_)
- Various fixes and extensions for cupy/CUDA, e.g. to use cuda for category_binning, spread, and dynspread, including cupy.interp where appropriate (`1015 <https://github.com/holoviz/datashader/pull/1015>`_, `#1016 <https://github.com/holoviz/datashader/pull/1016>`_, `#1044 <https://github.com/holoviz/datashader/pull/1044>`_, `#1050 <https://github.com/holoviz/datashader/pull/1050>`_, `#1060 <https://github.com/holoviz/datashader/pull/1060>`_)
- Infrastructure/build/ecosystem fixes (`1022 <https://github.com/holoviz/datashader/pull/1022>`_, `#1025 <https://github.com/holoviz/datashader/pull/1025>`_, `#1027 <https://github.com/holoviz/datashader/pull/1027>`_, `#1036 <https://github.com/holoviz/datashader/pull/1036>`_, `#1045 <https://github.com/holoviz/datashader/pull/1045>`_, `#1049 <https://github.com/holoviz/datashader/pull/1049>`_, `#1050 <https://github.com/holoviz/datashader/pull/1050>`_, `#1057 <https://github.com/holoviz/datashader/pull/1057>`_, `#1061 <https://github.com/holoviz/datashader/pull/1061>`_, `#1062 <https://github.com/holoviz/datashader/pull/1062>`_, `#1063 <https://github.com/holoviz/datashader/pull/1063>`_, `#1064 <https://github.com/holoviz/datashader/pull/1064>`_)

Compatibility:

- ``Canvas.line()`` option ``antialias=True`` is now deprecated; use ``line_width=1`` (or another nonzero value) instead. (`1048 <https://github.com/holoviz/datashader/pull/1048>`_)
- Removed long-deprecated ``bokeh_ext.py`` (`1059 <https://github.com/holoviz/datashader/pull/1059>`_)
- Dropped support for Python 2.7 (actually already dropped from the tests in Datashader 0.12) and 3.6 (no longer supported by many downstream libraries like rioxarray, but several of them are not properly declaring that restriction, making 3.6 much more difficult to support.) (`1033 <https://github.com/holoviz/datashader/pull/1033>`_)
- Now tested on Python 3.7, 3.8, 3.9, and 3.10. (`1033 <https://github.com/holoviz/datashader/pull/1033>`_)

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Thanks to Jim Bednar, Nezar Abdennur, Philipp Rudiger, and Jean-Luc Stevens.

Enhancements:

- Defined new ``dynspread metric`` based on counting the fraction of non-empty pixels that have non-empty pixels within a given radius. The resulting ``dynspread`` behavior is much more intuitive than the old behavior, which counted already-spread pixels as if they were neighbors (`1001 <https://github.com/holoviz/datashader/pull/1001>`_)
- Added ``ds.count()`` as the default reduction for ``ds.by`` (`1004 <https://github.com/holoviz/datashader/pull/1004>`_)

Bugfixes:

- Fixed array-bounds reading error in ``dynspread`` (`1001 <https://github.com/holoviz/datashader/pull/1001>`_)
- Fix ``color_key`` argument for ``dsshow`` (`986 <https://github.com/holoviz/datashader/pull/986>`_)
- Added Matplotlib output to the 3_Interactivity getting started page. (`1009 <https://github.com/holoviz/datashader/pull/1009>`_)
- Misc docs fixes (`1007 <https://github.com/holoviz/datashader/pull/1007>`_)
- Fix nan assignment to integer array in RaggedArray (`1008 <https://github.com/holoviz/datashader/pull/1008>`_)

Compatibility:

- Any usage of ``dynspread`` with datatypes other than points should be replaced with ``spread()``, which will do what was probably intended by the original ``dynspread`` call, i.e. to make isolated lines and shapes visible. Strictly speaking, dynspread could still be useful for other glyph types if that glyph is contained entirely in a pixel, e.g. if a polygon or line segment is located within the pixel bounds, but that seems unlikely.
- Dynspread may need to have the threshold or max_px arguments updated to achieve the same spreading as in previous releases, though the new behavior is normally going to be more useful than the old.

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Major release with new features that should really be considered part of the upcoming 0.13 release; please treat all the new features as experimental in this release due to it being officially a minor release (unintentionally).

Massive thanks to these contributors for substantial new functionality:

- Nezar Abdennur (nvictus), Trevor Manz, and Thomas Caswell for their contributions to the new ``dsshow()`` support for using Datashader as a Matplotlib Artist, providing seamless interactive Matplotlib+Datashader plots.
- Oleg Smirnov for ``category_modulo`` and ``category_binning`` for ``by()``, making categorical plots vastly more powerful.
- Jean-Luc Stevens for ``spread`` and ``dynspread`` support for numerical aggregate arrays and not just RGB images, allowing isolated datapoints to be made visible while still supporting hover, colorbars, and other plot features that depend on the numeric aggregate values.
- Valentin Haenel for the initial anti-aliased line drawing support (still experimental).

Thanks to Jim Bednar, Philipp Rudiger, Peter Roelants, Thuy Do Thi Minh, Chris Ball, and Jean-Luc Stevens for maintenance and other contributions.

New features:

- Expanded (and transposed) performance guide table (`961 <https://github.com/holoviz/datashader/pull/961>`_)
- Add ``category_modulo`` and ``category_binning`` for grouping numerical values into categories using by() (`927 <https://github.com/holoviz/datashader/pull/927>`_)
- Support spreading for numerical (non-RGB) aggregate arrays (`771 <https://github.com/holoviz/datashader/pull/771>`_, `#954 <https://github.com/holoviz/datashader/pull/954>`_)
- Xiaolin Wu anti-aliased line drawing, enabled by adding ``antialias=True`` to the ``Canvas.line()`` method call. Experimental; currently restricted to ``sum`` and ``max`` reductions ant only supporting a single-pixel line width. (`916 <https://github.com/holoviz/datashader/pull/916>`_)
- Improve Dask performance issue using a tree reduction (`926 <https://github.com/holoviz/datashader/pull/926>`_)

Bugfixes:

- Fix for xarray 0.17 raster files, supporting various nodata conventions (`991 <https://github.com/holoviz/datashader/pull/991>`_)
- Fix RaggedArray tests to keep up with Pandas test suite changes (`982 <https://github.com/holoviz/datashader/pull/982>`_, `#993 <https://github.com/holoviz/datashader/pull/993>`_)
- Fix out-of-bounds error on Points aggregation (`981 <https://github.com/holoviz/datashader/pull/981>`_)
- Fix CUDA issues (`973 <https://github.com/holoviz/datashader/pull/973>`_)
- Fix Xarray handling (`971 <https://github.com/holoviz/datashader/pull/971>`_)
- Disable the interactivity warning on the homepage (`983 <https://github.com/holoviz/datashader/pull/983>`_)

Compatibility:

- Drop deprecated modules ``ds.geo`` (moved to ``xarray_image``) and ``ds.spatial`` (moved to ``SpatialPandas``) (`955 <https://github.com/holoviz/datashader/pull/955>`_)

- Fixed InteractiveImage zooming to work with Bokeh 0.12.
- Added more responsive event throttling for DynamicImage; ``throttle`` parameter no longer needed and is now deprecated
- Fixed datashader-download-data command
- Improved non-geo Taxi example
- Temporarily disabled dashboard legends; will re-enable in future release

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No release notes produced.

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This release is primarily a compatibility release for newer versions of Rapids cuDF and Numba versions along with a small number of bug fixes. With contributions from `jonmmease <https://github.com/jonmmease>`_, `stuartarchibald <https://github.com/stuartarchibald>`_, `AjayThorve <https://github.com/AjayThorve>`_, `kebowen730 <https://github.com/kebowen730>`_, `jbednar <https://github.com/jbednar>`_ and `philippjfr <https://github.com/philippjfr>`_.

- Fixes support for cuDF 0.13 and Numba 0.48 (`933 <https://github.com/holoviz/datashader/pull/933>`_)
- Fixes for cuDF support on Numba>=0.51 (`934 <https://github.com/holoviz/datashader/pull/934>`_, `#947 <https://github.com/holoviz/datashader/pull/947>`_)
- Fixes tile generation using aggregators with output of boolean dtype (`949 <https://github.com/holoviz/datashader/pull/949>`_)
- Fixes for CI and build infrastructure (`935 <https://github.com/holoviz/datashader/pull/935>`_, `#948 <https://github.com/holoviz/datashader/pull/948>`_, `#951 <https://github.com/holoviz/datashader/pull/951>`_)
- Updates to docstrings (b1349e3, `950 <https://github.com/holoviz/datashader/pull/950>`_)