Windowed Reduce
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Windowed Reduce (/, ⌿), also called N-wise Reduce, is a primitive dyadic operator which takes a dyadic function, and a number as its left argument, inserts it between the overlapping "windows" of the size of its left argument, and evaluates it into a single array in right-to-left order.
Description
When applied to a vector argument, n f/x evaluates to the expression (a f b f c)(b f c f d) … where a, b, c, d, … are the elements of x, grouped into windows of size n. It works like Reduce, except applied on overlapping segments of an array, and borrows most of its functionality from it.
Examples
Windowed reduce is used to apply functions on overlapping sections of array e.g. when you need the deltas of an array.
3+/5 1 4 1 8
10 6 13
2-/1 2 3 4 5
¯1 ¯1 ¯1 ¯1
4,/35 56 67 79 91
┌───────────┬───────────┐
│35 56 67 79│56 67 79 91│
└───────────┴───────────┘
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