AggregateReplace
The AggregateReplace type describes a function that can be used to optimize a custom Aggregate by providing a shortcut for when a single value in the input values is replaced with another.
(
current: Cell,
add: Cell,
remove: Cell,
length: number,
): Cell | undefined
Type | Description | |
---|---|---|
current | Cell | The current value of the aggregation. |
add | Cell | The |
remove | Cell | The |
length | number | The length of the array of |
returns | Cell | undefined | The new value of the aggregation. |
Some aggregation functions do not need to recalculate the aggregation of the whole set when one value changes. For example, when replacing a number in a series, the new sum of the series is the previous sum, plus the new value, minus the old value.
If it is not possible to shortcut the aggregation based on just one value changing, return undefined
and the aggregation will be completely recalculated.
Where
possible, if you are providing a custom Aggregate, seek an implementation of an AggregateReplace function that can reduce the complexity cost of changing the input data set in place.
v2.0.0