比较两个日期时间的类型错误

Question

My problem will look common to you, but I didn't find the answer on the website. I want to combine two dates in python, I use this :

delta = 2012-04-07 18:54:40  - 2012-04-07 18:54:39

But I get an error : TypeError: unsupported operand type(s) for -: 'str' and 'str'

I understand it, but I don't know how to turn it the right way.

Do you have an idea?

Thks!

Answer 1

You are subtracting strings , not datetime.datetime objects. Try the strptime method in order to convert from strings to datetime.datetime .

>>> delta = datetime.datetime.strptime('2012-04-07 18:54:40', '%Y-%m-%d %H:%M:%S') \
            - datetime.datetime.strptime('2012-04-07 18:54:39', '%Y-%m-%d %H:%M:%S')
>>> delta
datetime.timedelta(0, 1)

Answer 2

Make them datetimes!

>>> import datetime
>>> datetime.datetime.now()
datetime.datetime(2013, 5, 13, 10, 25, 6, 20914)
>>> datetime.datetime(2013, 5, 13, 10, 25, 6, 20914)
datetime.datetime(2013, 5, 13, 10, 25, 6, 20914)
>>> datetime.datetime(2013, 5, 13, 10, 25, 6, 20914) - datetime.datetime(2013, 5, 13, 10, 14, 6, 20914)
datetime.timedelta(0, 660)
>>> 

Answer 3

If you want to calculate with datetimes, you first have to parse the date strings you've got.

One possibility is strptime, as mentioned. You can also use python-dateutil :

import dateutil.parser
dateutil.parser.parse("2012-04-07 18:54:40") - dateutil.parser.parse("2012-04-07 18:54:39")

# datetime.timedelta(0, 1)

which is easier to use. Also, there are a lot of other useful things for date handling in dateutil.