pandas.tseries.offsets.DateOffset — pandas 3.0.0.dev0+2100.gf496acffcc documentation (original) (raw)

class pandas.tseries.offsets.DateOffset#

Standard kind of date increment used for a date range.

Works exactly like the keyword argument form of relativedelta. Note that the positional argument form of relativedelta is not supported. Use of the keyword n is discouraged– you would be better off specifying n in the keywords you use, but regardless it is there for you. n is needed for DateOffset subclasses.

DateOffset works as follows. Each offset specify a set of dates that conform to the DateOffset. For example, Bday defines this set to be the set of dates that are weekdays (M-F). To test if a date is in the set of a DateOffset dateOffset we can use the is_on_offset method: dateOffset.is_on_offset(date).

If a date is not on a valid date, the rollback and rollforward methods can be used to roll the date to the nearest valid date before/after the date.

DateOffsets can be created to move dates forward a given number of valid dates. For example, Bday(2) can be added to a date to move it two business days forward. If the date does not start on a valid date, first it is moved to a valid date. Thus pseudo code is:

def add(date): date = rollback(date) # does nothing if date is valid return date +

When a date offset is created for a negative number of periods, the date is first rolled forward. The pseudo code is:

def add(date): date = rollforward(date) # does nothing if date is valid return date +

Zero presents a problem. Should it roll forward or back? We arbitrarily have it rollforward:

date + BDay(0) == BDay.rollforward(date)

Since 0 is a bit weird, we suggest avoiding its use.

Besides, adding a DateOffsets specified by the singular form of the date component can be used to replace certain component of the timestamp.

Attributes