Given a date, add time interval (X years, X months, X weeks), return date:
I looked at the datetime and datetime.timedelta docs
class datetime.timedelta(days=0, seconds=0, microseconds=0, milliseconds=0, minutes=0, hours=0, weeks=0)¶.
These works if I want to add a certain number of hours or weeks. However, I am trying to implement an operation such as date + 1 year:
start = datetime.datetime(2000, 1, 1)
# expected output: datetime.datetime(2001, 1, 1)
# with the weeks, etc arguments given in timedelta, this fails unsurprisingly e.g
start + datetime.timedelta(weeks = 52)
# returns datetime.datetime(2000, 12, 30, 0, 0)
Is this year-based operation possible with the basic tools of datetime - if so, how?
For the year example, I could just do start.replace(year = 2001), but that approach will fail if I have months or weeks as input.
The dateutil library seems more advanced, but I was not clear how well it interacts with the in-built datetime objects.
I reviewed this similar question.
Running Python 3.6.5 on MacOs.
timedelta does not support years, because the duration of a year depends on which year (for example, leap years have Feb 29).
You could use a relativedelta instead (from PyPI package python-dateutil) which does support years and takes into account the baseline date for additions.
>>> from dateutil.relativedelta import relativedelta
>>> import datetime
>>> d = datetime.date(2020, 2, 29)
>>> d
datetime.date(2020, 2, 29)
>>> d + relativedelta(years=1)
datetime.date(2021, 2, 28)