• Minimum Python version is now 3.6
• Update Vega-Lite to version 4.8.1; many new features and bug fixes from Vega-Lite versions 4.1 through 4.8; see Vega-Lite Release Notes.

Enhancements

• strokeDash encoding can now be used to control line styles (Example: Multi Series Line Chart
• chart.save() now relies on altair_saver for more flexibility (#1943).
• New chart.show() method replaces chart.serve(), and relies on altair_viewer to allow offline viewing of charts (#1988).

Bug Fixes

• Support Python 3.8 (#1958)
• Support multiple views in JupyterLab (#1986)
• Support numpy types within specifications (#1914)
• Support pandas nullable ints and string types (#1924)

##Maintenance

• Altair now uses black and flake8 for maintaining code quality & consistency.

Altair Version 4.0.0 release

Version 4.0.0 is based on Vega-Lite version 4.0, which you can read about at
https://github.com/vega/vega-lite/releases/tag/v4.0.0.

It is the first version of Altair to drop Python 2 compatibility, and is tested
on Python 3.5 and newer.

Enhancements

• Support for interactive legends: (Example)
  

• Responsive chart width and height: (Example)
  

• Bins responsive to selections: (Example)
  

• New pivot transform: (Example)
  

• New Regression transform: (Example)
  

• New LOESS transform: (Example)
  

• New density transform: (Example)
  

• Image mark (Example)
  

• New default html renderer, directly compatible with Jupyter Notebook and
  JupyterLab without the need for frontend extensions, as well as tools like
  nbviewer and nbconvert, and related notebook environments such as Zeppelin,
  Colab, Kaggle Kernels, and DataBricks. To enable the old default renderer, use:

  alt.renderers.enable('mimetype')
  

• Support per-corner radius for bar marks: (Example)
  

Grammar Changes

• Sort-by-field can now use the encoding name directly. So instead of

  alt.Y('y:Q', sort=alt.EncodingSortField('x_field', order='descending'))
  

  you can now use::

  alt.Y('y:Q', sort="-x")
  

• The rangeStep argument to :class:Scale and :meth:Chart.configure_scale is deprecated.
  instead, use chart.properties(width={"step": rangeStep}) or
  chart.configure_view(step=rangeStep).

• align, center, spacing, and columns are no longer valid chart properties, but
  are moved to the encoding classes to which they refer.

Version 3.3.0

released Nov 27, 2019

Last release to support Python 2

Enhancements

• Add inheritance structure to low-level schema classes (#1803)
• Add html renderer which works across frontends (#1793)
• Support Python 3.8 (#1740, #1781)
• Add :G shorthand for geojson type (#1714)
• Add data generator interface: alt.sequence, alt.graticule,
  alt.sphere() (#1667, #1687)
• Support geographic data sources via __geo_interface__ (#1664)

Bug Fixes

• Support pickle and copy.deepcopy for chart objects (#1805)
• Fix bug when specifying count() within transform_joinaggregate() (#1751)
• Fix LayerChart.add_selection (#1794)
• Fix arguments to project() method (#1717)
• Fix composition of multiple selections (#1707)

Version 3.2.0 (released August 5, 2019)

Upgraded to Vega-Lite version 3.4 (See Vega-Lite 3.4 Release Notes).

Following are changes to Altair in addition to those that came with VL 3.4:

Enhancements

• Selector values can be used directly in expressions (#1599)
• Top-level chart repr is now truncated to improve readability of error
  messages (#1572)

Bug Fixes

• top-level add_selection methods now delegate to sub-charts. Previously
  they produced invalid charts (#1607)
• Unsupported mark_*() methods removed from LayerChart (#1607)
• New encoding channels are properly parsed (#1597)
• Data context is propagated when encodings are specified as lists (#1587)

Backward-Incompatible Changes

• alt.LayerChart no longer has mark_*() methods, because they never
  produced valid chart specifications) (#1607)

Enhancements

• better handling of datetimes and timezones (#1053)

• all inline datasets are now converted to named datasets and stored at the
  top level of the chart. This behavior can be disabled by setting
  alt.data_transformers.consolidate_datasets = False (#951 & #1046)

• more streamlined shorthand syntax for window transforms (#957)

Maintenance

• update from Vega-Lite 2.4.3 to Vega-Lite 2.6.0; see vega-lite change-logs 2.5.0 2.5.1 2.5.2 2.6.0

Backward-incompatible changes

• alt.SortField renamed to alt.EncodingSortField and
  alt.WindowSortField renamed to alt.SortField (#923)

Bug Fixes

• Fixed serialization of logical operands on selections within
  transform_filter(): (#1075)

• Fixed sphinx issue which embedded chart specs twice (#1088)

• Avoid Selenium import until it is actually needed (#982)

Enhancements

• add a scale_factor argument to chart.save() to allow the
  size/resolution of saved figures to be adjusted. (#918)

• add an add_selection() method to add selections to charts (#832)

• add chart.serve() and chart.display() methods for more flexiblity
  in displaying charts (#831)

• allow multiple fields to be passed to encodings such as tooltip
  and detail (#830)

• make timeUnit specifications more succinct, by parsing them in a manner
  similar to aggregates (#866)

• make to_json() and to_csv() have deterministic filenames, so in json
  mode a single datasets will lead to a single on-disk serialization (#862)

Breaking Changes

• make data the first argument for all compound chart types to match the
  semantics of alt.Chart (this includes alt.FacetChart,
  alt.LayerChart, alt.RepeatChart, alt.VConcatChart, and
  alt.HConcatChart) (#895).

• update vega-lite to version 2.4.3 (#836)

  • Only API change is internal: alt.MarkProperties is now alt.MarkConfig

Maintenance

• update vega to v3.3 & vega-embed to v3.11 in html output & colab renderer (#838)

Nov 7, 2016

Major additions

• Update to Vega-Lite 1.2 and make all its enhancements available to Altair
• Add Chart.serve method
  (#197)
• Add altair.expr machinery to specify transformations and filterings
  (#213)
• Add Chart.savechart method, which can output JSON, HTML, and (if Node
  is installed) PNG and SVG. See https://altair-viz.github.io/documentation/displaying.html

Bug Fixes

• Countless minor bug fixes

Maintenance:

• Update to Vega-Lite 1.2.1 and add its supported features
• Create website: http://altair-viz.github.io/
• Set up Travis to run conda & pip; and to build documentation