datetime from string in Python, best-guessing string format

71
votes

The function to get a datetime from a string, datetime.strptime(date_string, format) requires a string format as the second argument. Is there a way to build a datetime from a string without without knowing the exact format, and having Python best-guess it?

4
pythondatetime
possible duplicate of Is there any python library for parsing dates and times from a natural language? - Andrew Walker
Differentiating between mm/dd/yyyy vs. dd/mm/yyyy is an interesting problem, with disastrous results if you get it wrong. - Mark Ransom
It depends how inexact you mean to be when you say, "without the exact format." Could you give examples of the types of inputs you want to be able to handle? Or, could you potentially have partial info about the format (such as whether the year is 2 or 4 digits, or whether the month precedes the day or vice versa)? Without at least some basic info, even a person can't do what you ask. Is 01/02/12 Feb 1st 2012, Jan 2nd 2012, Feb 12th 2001, Dec 2nd 2001, or something else? - Silas Ray
github.com/jeffreystarr/dateinfer - denfromufa
@denfromufa I get the following error while importing dateinfer on Python3: from infer import infer ModuleNotFoundError: No module named 'infer' - TanviP

4 Answers

115
votes

Use the dateutil library.

I was already using dateutil as an indispensable lib for handling timezones
(See Convert UTC datetime string to local datetime and How do I convert local time to UTC in Python?)

And I've just realized it has date parsing support:

import dateutil.parser
yourdate = dateutil.parser.parse(datestring)

(See also How do I translate a ISO 8601 datetime string into a Python datetime object?)

21
votes

Can get away with a simple function if only checking against dates.

def get_date(s_date):
    date_patterns = ["%d-%m-%Y", "%Y-%m-%d"]

    for pattern in date_patterns:
        try:
            return datetime.datetime.strptime(s_date, pattern).date()
        except:
            pass

    print "Date is not in expected format: %s" %(s_date)
    sys.exit(0)
7
votes

Back before I was a python guy, I was a perl guy. One of the things that I've always missed but haven't seen anything close to it is Date::Manip. That module can extract a good timestamp from a smattering of nibbles. I almost suspect that it's author struck a deal with the Devil.

I've run across a few things that take stabs at it in Python:

If you find anything better I'd love to hear about it though.

4
votes

You can use datefinder ,It will detect all types of natural style of dates.

import datefinder # Module used to find different style of date with time

string_value = " created 01/15/2005 by ACME inc.and associates.January 4th,2017 at 8pm"
matches = datefinder.find_dates(string_value)            
for match in matches:
    print("match found ",match)

Output

match found  2005-01-15 00:00:00
match found  2017-01-04 20:00:00