sumbars

sumbars(X, Y)

X is a vector/tuple/matrix/table whose elements must be non-negative numbers.

Y is a vector/scalar.

• If X is a vector, Y is a scalar.

• If X is a tuple, Y is a vector with the same length as X.

• If X is a matrix/table, Y is a vector with the same length as the number of columns of X.

For each element X _i in X, calculate the cumulative sum of X _i in the backward direction, i.e., (X _i + X _i-1 + X _i-2 …), until the value is no smaller than Y.

If the cumulative sum never exceeds Y, return 0.

sumbars(1 2 3.3 2 5, 3)
// output
[0,2,1,2,1]

sumbars(matrix(5 3 6 2 3, 2 6 1 5 4), [5, 8])

// calculate the turnover period
id = `A`A`B`A`C`B`A`C`A`B
time = 2022.01.01T09:00:00 + 0..9
volume = 100 150 80 120 220 200 180 90 100 125
t = table(id, time, volume)
capital = 300
re = select *, sumbars(volume, capital) as period from t
re;