Highlights of new additions in v5.4.0:

• Add statistical regression, loess, and kde transforms, with groupby support.
• Add gradients (linear and radial) for use as fill or stroke colors.
• Add prev_value, next_value fill operation for the window transform.
• Add legendX and legendY properties to position legends with orient "none".
• Add isDefined and isValid expression functions.
• Add filter option for TopoJSON mesh extraction.
• Add support for expr-valued sort fields.
• Improve encoding update efficiency.

Changes from v5.3.5:

vega

• Update test specifications.

vega-encode

• Add mod parameter to Encode transform to control inclusion of mod tuples that are not updated by the encoders.

vega-functions

• Add isDefined and isValid expression functions.

vega-geo

• Add nomod metadata flag to GeoShape transform.
• Add null value filter when marshaling GeoJSON data for projection fit.
• Add test case for null GeoJSON values.

vega-loader

• Add filter property to TopoJSON format.
• Add test cases for TopoJSON format filter.

vega-parser

• Add value update checks to generated encoder functions, add only updated items to the mod set. Results in more efficient re-rendering when only a subset of items have encoded values modified. If a mark includes a post-encoding transform that lacks a nomod metadata flag, disable mod set filtering by the encoder to ensure proper pulse propagation.
• Add support for expr-valued sort fields.
• Add legendX / legendY properties to legend parser.

vega-regression

• Create regression package, add regression and loess transforms.

vega-scenegraph

• Update gradient handling to add id and default values, as needed.
• Add radial gradient support, via pattern wrapping.
• Update scenegraph JSON schema.

vega-schema

• Add usermeta support for all scopes, not just the top-level.
• Add expr-valued sort fields to schema.
• Add DSV/CSV/TSV header property to schema.
• Add filter property to TopoJSON format schema.
• Add legendX / legendY properties to legend schema.
• Add explicit linear and radial gradient color values to schema.
• Add new transforms to schema.

vega-statistics

• Add regression methods, adapting @HarryStevens' d3-regression work. (Thanks!)
• Add sampleCurve method for adaptive subdivision of interpolated curves.
• Update number coercion and valid value filtering.
• Document new methods in README.md.

vega-transforms

• Add KDE transform and tests.
• Add prev_value, next_value window operations.
• Add minsteps and maxsteps parameters to Density transform.
• Minor updates to Compare transform.

vega-typings

• Add expr-valued sort fields to typings.
• Add DSV/CSV/TSV header property to typings. Refactor DSV typings.
• Add filter property to TopoJSON format typings.
• Add legendX/legendY properties to legend typings.
• Add explicit linear and radial gradient color values to typings.
• Add KDE, Loess, and Regression transforms to typings.
• Add prev_value, next_value window operations to typings.

monorepo

• Update dev dependencies.