Add JoinAggregateTransform to a vega-lite spec.
An input vega-lite spec
The definition of the fields in the join aggregate, and what calculations to use.
The data fields for partitioning the data objects into separate groups. If unspecified, all data points will be in a single group.
Directly input an object, rather than creating one via the other arguments. Should not be used in conjunction with the other arguments other than
spec. Objects can be of type: JoinAggregateTransform