python get past day ago from date code example

Example 1: datetimes to day of year python

>>> import datetime
>>> today = datetime.datetime.now()
>>> print today
2009-03-06 15:37:02.484000
>>> today.strftime('%j')
'065'

Example 2: 1 day ago python datetime

date_N_days_ago = datetime.now() - timedelta(days=N)