119

As an input to an API request I need to get yesterday's date as a string in the format YYYY-MM-DD. I have a working version which is:

yesterday = datetime.date.fromordinal(datetime.date.today().toordinal()-1)
report_date = str(yesterday.year) + \
   ('-' if len(str(yesterday.month)) == 2 else '-0') + str(yesterday.month) + \
   ('-' if len(str(yesterday.day)) == 2 else '-0') + str(yesterday.day)

There must be a more elegant way to do this, interested for educational purposes as much as anything else!

Mazdak
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Jacob
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    You can look at this: http://stackoverflow.com/questions/1712116/formatting-yesterdays-date-in-python?rq=1 and just modify the format string – EdChum May 27 '15 at 13:31

5 Answers5

215

You just need to subtract one day from today's date. In Python datetime.timedelta object lets you create specific spans of time as a timedelta object.

datetime.timedelta(1) gives you the duration of "one day" and is subtractable from a datetime object. After you subtracted the objects you can use datetime.strftime in order to convert the result --which is a date object-- to string format based on your format of choice:

>>> from datetime import datetime, timedelta
>>> yesterday = datetime.now() - timedelta(1)

>>> type(yesterday)
>>> datetime.datetime

>>> datetime.strftime(yesterday, '%Y-%m-%d')
'2015-05-26'

Note that instead of calling the datetime.strftime function, you can also directly use strftime method of datetime objects:

>>> (datetime.now() - timedelta(1)).strftime('%Y-%m-%d')
'2015-05-26'

As a function:

from datetime import datetime, timedelta


def yesterday(frmt='%Y-%m-%d', string=True):
    yesterday = datetime.now() - timedelta(1)
    if string:
        return yesterday.strftime(frmt)
    return yesterday

example:

In [10]: yesterday()
Out[10]: '2022-05-13'

In [11]: yesterday(string=False)
Out[11]: datetime.datetime(2022, 5, 13, 12, 34, 31, 701270)
Mazdak
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29

An alternative answer that uses today() method to calculate current date and then subtracts one using timedelta(). Rest of the steps remain the same.

https://docs.python.org/3.7/library/datetime.html#timedelta-objects

from datetime import date, timedelta
today = date.today()
yesterday = today - timedelta(days = 1)
print(today)
print(yesterday)

Output: 
2019-06-14
2019-06-13
Francis Colas
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theRahulMody
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    **This answer is misleading**. Note that you still have to convert your date objects to string. `print` function automatically prints the date in that format but that doesn't mean the objects are string and formatted that way! – Mazdak Jan 23 '20 at 14:52
10
>>> import datetime
>>> datetime.date.fromordinal(datetime.date.today().toordinal()-1).strftime("%F")
'2015-05-26'
Paul Rubel
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6

Calling .isoformat() on a date object will give you YYYY-MM-DD

from datetime import date, timedelta
(date.today() - timedelta(1)).isoformat()
Kevin Nasto
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1

I'm trying to use only import datetime based on this answer.

import datetime

oneday = datetime.timedelta(days=1)
yesterday = datetime.date.today() - oneday
M Koetz
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