Version 2.1.0

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)