businessYearBegin

businessYearBegin(X, [startingMonth=1], [offset], [n=1])

Return the first business day (Monday to Friday) of the year that X belongs to and that starts in the month of startingMonth.

By default, each period corresponds to one year, and the function returns the first business day of the year containing X. The starting month of the year is determined by the startingMonth parameter. Here, business days are determined solely by the day of the week: Monday through Friday are considered business days, while Saturday and Sunday are considered non-business days.

When both offset and n are specified and n > 1, the function calculates period start dates based on n-year periods. In this case, offset determines how multi-year periods are aligned. Specifically, the system first calculates the first business day of the year containing offset according to startingMonth, and uses that date as the reference point. A new period start boundary is then generated every n years, and the function returns the first business day corresponding to the period to which X belongs.

DolphinDB and pandas both provide similar date offset functionality at the conceptual level. For a comparison of calculation rules, see Functions Related to Date Offset.

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

startingMonth (optional) is an integer between 1 and 12 indicating a month. The default value is 1.

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.

A scalar/vector of type DATE.

businessYearBegin(2012.06.12);
// output: 2012.01.02

businessYearBegin(2012.06.13 10:10:10.008,5);
// output: 2012.05.01

date=2011.10.25 2012.10.25 2013.10.25 2014.10.25 2015.10.25 2016.10.25 2017.10.25 2018.10.25 2019.10.25 2020.10.25
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 businessYearBegin(date,1,2011.10.01,2)

Related functions: businessYearEnd, yearBegin, yearEnd