# lastWeekOfMonth

Syntax

lastWeekOfMonth(X, [weekday=0], [offset], [n=1])

Arguments

X is a scalar/vector of type DATE, DATETIME, TIMESTAMP or NANOTIMESTAMP.

weekday is an integer from 0 to 6. 0 means Monday, 1 means Tuesday, …, and 6 means Sunday. The default value is 0.

offset is a scalar of the same data type as X. It must be no greater than the minimum value of X. The default value is the minimum value of X.

n is a positive integer. The default value is 1.

Details

In the calendar month of X, suppose the last “weekday” is d.

• If X <d: return the last “weekday” in the previous calendar month.

• If X >=d: return the last “weekday” in the current calendar month.

If parameter offset is specified, the result is updated every n months. Parameter offset works only if parameter n >1.

Examples

```\$ lastWeekOfMonth(2019.11.24,2);
2019.10.30
// The last Wednesday of November 2019 is 2019.11.27, 2019.11.24 is before 2019.11.27, so the function returns the last Wednesday of October 2019.

\$ lastWeekOfMonth(2019.11.29,2);
2019.11.27

\$ date=2012.01.02 2012.02.03 2012.03.07 2012.04.08 2012.05.12 2012.06.16 2012.07.18 2012.08.20 2012.09.25 2012.10.28
\$ time = [09:34:07,09:36:42,09:36:51,09:36:59,09:32:47,09:35:26,09:34:16,09:34:26,09:38:12,09:38:13]
\$ sym = take(`MSFT,10)
\$ price= 49.6 29.46 29.52 30.02 174.97 175.23 50.76 50.32 51.29 52.38
\$ qty = 2200 1900 2100 3200 6800 5400 1300 2500 8800 4500
\$ t1 = table(date, time, sym, qty, price);

\$ select avg(price),sum(qty) from t1 group by lastWeekOfMonth(date,4,2012.01.01,2);
```

lastWeekOfMonth_date

avg_price

sum_qty

2011.12.30

39.53

4100

2012.02.24

29.77

5300

2012.04.27

175.1

12200

2012.06.29

50.54

3800

2012.08.31

51.29

8800

2012.10.26

52.38

4500