defaultdict and datetime

[Jason Friedman]

$ python3
Python 3.6.1 (default, Apr 8 2017, 09:56:20)
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import collections, datetime
>>> x = collections.defaultdict(int)
>>> x['something']
0
>>> x = collections.defaultdict(datetime.datetime)
>>> x['something']
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: Required argument 'year' (pos 1) not found

I would like to have a dictionary where the default value is a
datetime.datetime object, preferably something small like January 1, year 1.

[MRAB]

For the value you can use datetime.datetime.min.

The argument to defaultdict must be a function that takes no arguments.
You can use lambda for that:

x = collections.defaultdict(lambda: datetime.datetime.min)