getdate

Calendar.getdate(expr, ref) resolves date expressions against month, year, or date references. It returns numpy.datetime64 for scalar calls and numpy.ndarray for vectorized calls.

The expr argument has three forms:

  • <position> <day>, such as first day, 15th day, last bizday, next wed

  • <position> <day> <before|after> <position> <day>, such as first day before 15th day or 1st bizday before 2nd fri

  • previous <weekday>, such as previous mon

Positions are next, first/1st, second/2nd, third/3rd, <n> with the right English suffix (4th, 11th, 21st, 22nd) and last. Days are day, bizday, or a weekday as a 3-letter or full English name (mon/monday … sun/sunday). Words are case-insensitive; any other word raises ValueError.

Reference rules:

  • year or month refs: the n-th day, business day or weekday inside the period; last is the last one and next means the first. Composite expressions work with period refs only.

  • date refs: <n> day is the date plus n days, <n> bizday is offset(date, n), and <n> <weekday> is the n-th such weekday strictly after the date. last (or previous, for weekdays) gives the one strictly before.

  • all refs in one call must be of one kind (year, month or date).

[1]:

from bizdays import Calendar

cal = Calendar.load(name="ANBIMA")

Month references use YYYY-MM strings.

[2]:

cal.getdate("15th day", "2002-05")

[2]:

np.datetime64('2002-05-15')

[3]:

cal.getdate("first day before 15th day", "2002-01")

[3]:

np.datetime64('2002-01-14')

[4]:

cal.getdate(["last day", "last bizday"], "2006")

[4]:

array(['2006-12-31', '2006-12-29'], dtype='datetime64[D]')

The last business day of a month. All refs in one call must be of one kind: mixing month and date refs raises ValueError.

[5]:

cal.getdate("last bizday", "2024-02")

[5]:

np.datetime64('2024-02-29')

Year references can be integers or year strings.

[6]:

cal.getdate("first bizday", 2002)

[6]:

np.datetime64('2002-01-02')

Date references resolve the expression relative to that day.

[7]:

cal.getdate("next wed", "2021-02-10")

[7]:

np.datetime64('2021-02-17')

[8]:

cal.getdate("previous mon", "2021-02-10")

[8]:

np.datetime64('2021-02-08')

[9]:

cal.getdate("second fri", "2026-04-20")

[9]:

np.datetime64('2026-05-01')

[10]:

cal.getdate(["next bizday", "last bizday"], "2022-06-18")

[10]:

array(['2022-06-20', '2022-06-17'], dtype='datetime64[D]')

[11]:

cal.getdate("last mon", "2022-06-20")

[11]:

np.datetime64('2022-06-13')

Both the expression and the reference can be vectorized, with refs of one kind per call.

[12]:

cal.getdate(["15th day", "16th day"], ["2002-01", "2001-01"])

[12]:

array(['2002-01-15', '2001-01-16'], dtype='datetime64[D]')

[13]:

cal.getdate(["next wed", "previous mon"], ["2021-02-10", "2021-02-10"])

[13]:

array(['2021-02-17', '2021-02-08'], dtype='datetime64[D]')