Detect if a variable is a datetime object

Question

I have a variable and I need to know if it is a datetime object.

So far I have been using the following hack in the function to detect datetime object:

i         


        

Answer 1

You can also check using duck typing (as suggested by James).

Here is an example:

from datetime import date, datetime

def is_datetime(dt):
    """
    Returns True if is datetime
    Returns False if is date
    Returns None if it is neither of these things
    """
    try:
        dt.date()
        return True
    except:
        if isinstance(dt, date):
            return False
    return None

Results:

In [8]: dt = date.today()
In [9]: tm = datetime.now()
In [10]: is_datetime(dt)
Out[11]: False
In [12]: is_datetime(tm)
Out[13]: True
In [14]: is_datetime("sdf")
In [15]:

Answer 2

isinstance is your friend

>>> thing = "foo"
>>> isinstance(thing, str)
True

Answer 3

Note, that datetime.date objects aer not considered to be of datetime.datetime type, while datetime.datetime objects are considered to be of datetime.date type.

import datetime                                                                                                                     

today = datetime.date.today()                                                                                                       
now = datetime.datetime.now()                                                                                                       

isinstance(today, datetime.datetime)                                                                                                
>>> False

isinstance(now, datetime.datetime)                                                                                                  
>>> True

isinstance(now, datetime.date)                                                                                                      
>>> True

isinstance(now, datetime.datetime)                                                                                                  
>>> True

Answer 4

I believe all the above answer will work only if date is of type datetime.datetime. What if the date object is of type datetime.time or datetime.date?

This is how I find a datetime object. It always worked for me. (Python2 & Python3):

import datetime
type(date_obj) in (datetime, datetime.date, datetime.datetime, datetime.time)

Testing in Python2 or Python3 shell:

import datetime
d = datetime.datetime.now()  # creating a datetime.datetime object.
date = d.date()  # type(date): datetime.date
time = d.time()  # type(time): datetime.time

type(d) in (datetime, datetime.date, datetime.datetime, datetime.time)
True
type(date) in (datetime, datetime.date, datetime.datetime, datetime.time)
True
type(time) in (datetime, datetime.date, datetime.datetime, datetime.time)
True

Answer 5

You need isinstance(variable, datetime.datetime):

>>> import datetime
>>> now = datetime.datetime.now()
>>> isinstance(now, datetime.datetime)
True

Update

As noticed by Davos, datetime.datetime is a subclass of datetime.date, which means that the following would also work:

>>> isinstance(now, datetime.date)
True

Perhaps the best approach would be just testing the type (as suggested by Davos):

>>> type(now) is datetime.date
False
>>> type(now) is datetime.datetime
True

Pandas Timestamp

One comment mentioned that in python3.7, that the original solution in this answer returns False (it works fine in python3.4). In that case, following Davos's comments, you could do following:

>>> type(now) is pandas.Timestamp

If you wanted to check whether an item was of type datetime.datetime OR pandas.Timestamp, just check for both

>>> (type(now) is datetime.datetime) or (type(now) is pandas.Timestamp)

Answer 6

Use isinstance.

if isinstance(variable,datetime.datetime):
    print "Yay!"