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Logical function
REDUCE
Accumulates a single result by applying a LAMBDA across an array.
OccasionalDifficulty 1800 · ExpertUsage rank #101 of 520
When to use it
Folds an array into one value by applying a LAMBDA with an accumulator to each element in turn.
The shape of it
- Syntax
=REDUCE([initial_value], array, lambda)
Worked examples
Sum by hand
=REDUCE(0,{1,2,3,4},LAMBDA(acc,x,acc+x)) → 10
A sum built step by step.
Product
=REDUCE(1,{2,3,4},LAMBDA(a,x,a*x)) → 24
A product.
Build a string
=REDUCE("",A2:A4,LAMBDA(a,x,a&x&";")) → Widget;Gadget;Gizmo;
Building text.
Worth knowing
- Use it for calculations that depend on the previous step, like compounding with varying rates.
- The initial value sets the accumulator's type.
- SCAN returns every intermediate value instead of just the last.
Where it goes wrong
- Slow on very large arrays; use native functions when one exists.
- Requires Microsoft 365.
Related
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