# cumstdTopN

Syntax

cumstdTopN(X, S, top, [ascending=true], [tiesMethod=’latest’])

Please see Cumulative Moving TopN Functions (cumTopN functions) for the parameters and windowing logic.

Details

After stably sorting S in the specified ascending order, the function calculates the standard deviation of the first top elements of X in a cumulative window.

Return value: DOUBLE type.

Examples

```\$ X=1 2 3 10 100 4 3
\$ S = 0.3 0.5 0.1 0.1 0.5 0.2 0.4
\$ cumstdTopN(X, S, 6, 4)
[,0.70,1,4.08,43.07,39.31,39.22]

\$ X = matrix(1..10, 11..20)
\$ S = matrix(2022.01.01 2022.02.03 2022.01.23 NULL 2021.12.29 2022.01.20 2022.01.23 2022.01.22 2022.01.24 2022.01.24, NULL 2022.02.03 2022.01.23 2022.04.06 NULL 2022.02.03 2022.02.03 2022.02.05 2022.02.08 2022.02.03)
\$ cumstdTopN(X, S, 6, 4)
```

#0

#1

0.7071

1

0.7071

1

1

1.7078

1

2.0736

1.7078

2.3664

2.0736

2.6077

2.3664

2.6077

2.7869

2.6077

3.0332

```\$ id=rand(10,10)
\$ price=rand(100,10)
\$ t=table(id, price)
\$ select cumavgTopN(price, id, 6, 4) as result from t
```

result

94

69.5

46.3333

55.75

57.8

49.6667

50.5

50.5

51.5

51.5