Optimized Transforms

VegaFusion supports optimizing a subset of Vega’s transforms. Below is a detailed breakdown of transform support status.

Note

When a Vega spec includes unsupported transforms, these transforms will be included in the client Vega spec for evaluation by the standard Vega library in the browser. See How it works for more details.

Key:

• ✅: Full optimization support for the transform and all its options

• 🟡: Partial optimization support for the transform with limitations

• ❌: Transform is not currently eligible for optimization

Basic Transforms

Transform	Status	Details
aggregate	🟡	More Info Supported aggregate ops: count valid missing distinct sum mean or average variance variancep stdev stdevp median q1 q3 min max Unsupported aggregate ops: product ci0 ci1 stderr argmin argmax The cross, drop, and key options are not yet supported.
formula	✅	More Info See optimized expressions for details on supported expression features that may be used in the expr field.
window	🟡	More Info Supported window operations: Ranking operations: row_number rank dense_rank percent_rank cume_dist Value operations: first_value last_value All supported aggregate transform ops Not yet supported: ntile lag/lead nth_value prev_value/next_value All frame specifications and peer handling options are supported.
lookup	❌
bin	✅	More Info interval option ignored and both bin edges are always included.
collect	✅
extent	✅
filter	✅	More Info See optimized expressions for details on supported expression features that may be used in the expr field.
flatten	❌	More Info May be possible in the future with DataFusion’s unnest transform.
fold	✅
project	✅
sequence	✅
timeunit	🟡	More Info interval option ignored and both bin edges are always included. step, extent, and maxbins options are not supported, so units must be provided.
countpattern	❌
cross	❌
density	❌
dotbin	❌
identifier	✅
impute	🟡	More Info Supported: field - Field to impute key - Unique identifier field value - Custom value for imputation groupby - Group-based imputation Unsupported: method parameter with options other than value keyvals array for custom key values
kde	❌
loess	❌
pivot	✅
quantile	❌
regression	❌
sample	❌

Geographic and Spatial Transforms

Transform	Status	Details
contour	❌
geojson	❌
geopath	❌
geopoint	❌
geoshape	❌
graticule	❌
heatmap	❌
isocontour	❌
kde2d	❌

Layout Transforms

Transform	Status	Details
stack	✅
force	❌
label	❌
linkpath	❌
pie	❌
voronoi	❌
wordcloud	❌

Hierarchy Transforms

Transform	Status	Details
nest	❌
stratify	❌
treelinks	❌
pack	❌
partition	❌
tree	❌
treemap	❌

Cross-Filter Transforms

Transform	Status	Details
crossfilter	❌
resolvefilter	❌