AggregateRemove

The AggregateRemove type describes a function that can be used to optimize a custom Aggregate by providing a shortcut for when a single value is removed from the input values.

(
  current: Cell,
  remove: Cell,
  length: number,
): ResultCellOrUndefined

Some aggregation functions do not need to recalculate the aggregation of the whole set when one value changes. For example, when removing a number from a series, the new sum of the series is the new value subtracted from the previous sum.

If it is not possible to shortcut the aggregation based on just one value being removed, return undefined and the aggregation will be completely recalculated. One example might be if you were taking the minimum of the values, and the previous minimum is being removed. The whole of the rest of the list will need to be re-scanned to find a new minimum.

When possible, if you are providing a custom Aggregate, seek an implementation of an AggregateRemove function that can reduce the complexity cost of shrinking the input data set.