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Posts Tagged ‘timedelta’

subtract a day from a python date

July 10, 2015 Leave a comment

Problem
When working with dates, I prefer the order yyyy-mm-dd (e.g. 2015-07-10). Its main advantage is that if you use it as a prefix and sort your entries, you get them in chronological order. (Another advantage is that in my home country we use this order, so this is much closer to my thinking).

So, I faced the following problem: having a date as a string (“2015-07-10”), calculate the date one day before and produce a string again (“2015-07-09”).

Solution

>>> from datetime import datetime, timedelta
>>> date = "2015-07-10"
>>> today = datetime.strptime(date, '%Y-%m-%d')
>>> today
datetime.datetime(2015, 7, 10, 0, 0)
>>> yesterday = today - timedelta(days=1)
>>> yesterday
datetime.datetime(2015, 7, 9, 0, 0)
>>> yesterday.strftime('%Y-%m-%d')
'2015-07-09'

Links

Remark
Back to dates: if I need to write a date in English, I write it like this: “May 12, 1984”. Avoid “05-12-1984”, because what is it? May 12? Or December 5? God knows only.

Categories: python Tags: , , , ,