Altair

Complete rewrite of Altair, focused on supporting Vega-Lite 2.X

This version of Altair is based on Vega-Lite 1.2.1.

Major additions

- Support for JupyterLab/nteract through MIME based rendering. Enable this by calling `enable_mime_rendering()` before rendering visualizations (216).

- Change default import in all code and docs to `import altair as alt`

- Check for missing and misspelled column names upon exporting or rendering, and raise `FieldError` (399) if any problems are found. This can be disabled by setting `Chart.validated_columns=False`.

- Raise `MaxRowsExceeded` if the number of rows in the dataset is larger than `Chart.max_rows` to guard against sending large datasets to the browser.

- Move the Vega-Lite 1.x api into `altair.v1` to make it easier for us to migrate to Vega-Lite 2.x and continue to support 1.x. No import change are needed as `altair.v1` is aliased to `altair` in this release (377).

- Moved the example notebooks into a separate repository (https://github.com/altair-viz/altair_notebooks) that has Binder support (#391).

- Add `$schema` to top-level JSON spec (370).

- Minor documentation revisions.

Bug fixes

- Make sure default mark is a point (344).

Nov 7, 2016

Major additions
- Update to Vega-Lite 1.2 and make all its enhancements available to Altair
- Add `Chart.serve` method
([197](https://github.com/altair-viz/altair/pull/197))
- Add `altair.expr` machinery to specify transformations and filterings
([213](https://github.com/altair-viz/altair/pull/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

Initial release of Altair