semiMonthBegin

semiMonthBegin(X, [dayOfMonth=15], [offset], [n=1])

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

dayOfMonth (optional) is an integer between 2 and 27. The default value is 15.

offset (optional) 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 (optional) is a positive integer. The default value is 1.

Return the first day of the semi-month that X belongs to. Suppose X is the d-th day of the month:

• If d < dayOfMonth: return the first day of the month.

• If d >= dayOfMonth: return the dayOfMonth-th day of the month.

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

semiMonthBegin(2012.06.12);
// output
2012.06.01

semiMonthBegin(2012.06.24);
// output
2012.06.15

semiMonthBegin(2012.06.15);
// output
2012.06.15

semiMonthBegin(2012.06.16, 16);
// output
2012.06.16


date=2016.04.07+(1..10)*7
time = take(09:30:00, 10);
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);
t1;

select avg(price),sum(qty) from t1 group by semiMonthBegin(date);