pandas.tseries.offsets.DateOffset — pandas 0.24.0rc1 documentation (original) (raw)
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 +
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 +
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 |
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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. |
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| freqstr | | | -------------- | | | kwds | | | name | | | nanos | | | rule_code | |
Methods
| apply_index | Vectorized apply of DateOffset to DatetimeIndex, raises NotImplentedError for offsets without a vectorized implementation. |
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| 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 | |