rolling

Series rolling(Series s,  size_t windowSize,  size_t minPeriods,
       string agg)

@trusted

Computes a rolling aggregation over fixed-width receding frames (ADR-2026-10-24-17): row i sees [max(0, i - windowSize + 1) .. i] inclusive; minPeriods (default 1) nulls rows with too few valid slots; nulls are skipped (not counted); the float association is the chunk-ordered serial left fold.

Parameters

`s`	the input Series
`windowSize`	the receding frame width (at least 1)
`minPeriods`	the minimum valid slots for a non-null output
`agg`	"sum", "mean", "count", "min", or "max"

Returns

the rolling-aggregated Series.

Throws

DataFrameException on unsupported kinds or invalid widths.

Series rolling(Series s,  size_t windowSize,  size_t minPeriods,
       string agg,  size_t ddof)

@trusted

Ditto, with the dispersion degrees of freedom: ddof applies to the "std" and "variance" aggregations only (default 1; a window whose valid count is <= ddof reads null; ADR-2026-10-28-01).

Parameters

`s`	the value column
`windowSize`	the receding frame width (at least 1)
`minPeriods`	the minimum valid slots for a non-null output
`agg`	the aggregation name
`ddof`	the dispersion degrees of freedom

Returns

the per-window aggregation (FLOAT64).

Throws

DataFrameException on invalid widths, an unknown

aggregation, or ddof passed for a non-dispersion aggregation.