pandas.tseries.offsets.DateOffset¶
-
class
pandas.tseries.offsets.
DateOffset
(n=1, normalize=False, **kwds)[source]¶ Standard kind of date increment used for a date range.
Works exactly like relativedelta in terms of the keyword args you pass in, 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.
DateOffets work 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 onOffset method: dateOffset.onOffset(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 + <n number of periods>
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 is date is valid return date + <n number of periods>
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.
Parameters: - n : int, default 1
The number of time periods the offset represents.
- normalize : bool, default False
Whether to round the result of a DateOffset addition down to the previous midnight.
- **kwds
Temporal parameter that add to or replace the offset value.
Parameters that add to the offset (like Timedelta):
- years
- months
- weeks
- days
- hours
- minutes
- seconds
- microseconds
- nanoseconds
Parameters that replace the offset value:
- year
- month
- day
- weekday
- hour
- minute
- second
- microsecond
- nanosecond
See also
Examples
>>> ts = pd.Timestamp('2017-01-01 09:10:11') >>> ts + DateOffset(months=3) Timestamp('2017-04-01 09:10:11')
>>> ts = pd.Timestamp('2017-01-01 09:10:11') >>> ts + DateOffset(month=3) Timestamp('2017-03-01 09:10:11')
Attributes
base
Returns a copy of the calling offset object with n=1 and all other attributes equal. freqstr kwds name nanos rule_code Methods
apply_index
Vectorized apply of DateOffset to DatetimeIndex, raises NotImplentedError for offsets without a vectorized implementation. rollback
(dt)Roll provided date backward to next offset only if not on offset. rollforward
(dt)Roll provided date forward to next offset only if not on offset. __call__ apply copy isAnchored onOffset