Date object with year and month only

问题:

Is it possible to create date object with year and month only? I don't need day.

In [5]: from datetime import date

In [6]: date(year=2013, month=1)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-6-a84d4034b10c> in <module>()
----> 1 date(year=2013, month=1)

TypeError: Required argument 'day' (pos 3) not found

I'm using the date object as key in my dictionary and January 20 must have the same key as January 21, because they are in same month and year.

I used a simple integer before that as a month number. Unfortunately I need to know the year too!

回答1:

No, you can't do that. For your usecase, use a tuple instead:

key = (2013, 1)

Since you don't need to do date manipulations on the value a tuple more than suffices.

回答2:

As an addition to other answer, you can use namedtuple.

from collections import namedtuple
MyDate = namedtuple('MyDate', ['month', 'year'])
dkey = MyDate(year=2013, month=1)

回答3:

import datetime

date = datetime.date(year=2013, month=1, day=4)
str(date.year) + '-' + str(date.month)

回答4:

If you want to use datetime, you must follow its attributes. Here I quote it from the official website:

"An idealized naive date, assuming the current Gregorian calendar always was, and always will be, in effect. Attributes: year, month, and day."

So, you can't ignore day and remember to give assignment.