overAgg

Series overAgg(DataFrame df,  string column,  string[]  keys,
       string agg)

@trusted

Computes a partitioned aggregation and scatters each partition's result back to every input row of that partition (the over semantics of ADR-2026-10-24-17: the output has the input's length and row order).

Parameters

`df`	the frame
`column`	the column to aggregate
`keys`	the partition key column names
`agg`	the aggregation name ("sum", "count", "mean", "min", "max", "first", "last", "median", "std", "variance")

Returns

the per-row aggregate Series (the input's length).

Throws

DataFrameException for missing columns or unsupported

aggregations.

Series overAgg(DataFrame df,  string column,  string[]  keys,  string agg,
       double  param)

@trusted

Ditto, with the statistical parameter: q for "quantile" (default 0.5 - "median" is its alias), ddof for "std" and "variance" (default 1; ADR-2026-10-28-01).

Parameters

`df`	the frame
`column`	the aggregated column
`keys`	the partition keys
`agg`	the aggregation name
`param`	the statistical parameter (q or ddof)

Returns

the partitioned aggregate scattered to input rows.