Python string to datetime – strptime()

We can convert a string to datetime using strptime() function. This function is available in datetime and time modules to parse a string to datetime and time objects respectively.

Python strptime()

Python strptime() is a class method in datetime class. Its syntax is:

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datetime.strptime(date_string, format)

Both the arguments are mandatory and should be string. This function is exactly opposite of strftime() function, which converts datetime object to a string.

We have the similar function available in time module too, where its syntax is:

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time.strptime(time_string[, format])

Here the function returns struct_time object. If format string is not provided, it defaults to “%a %b %d %H:%M:%S %Y” which matches the formatting returned by ctime() function.

If the input string cannot be parsed according to the provided format, then ValueError is raised. The exception message provides clear details about the issue in parsing.

Python strptime() format directives

Following table contains most of the commonly used format directives.

Python strptime() examples

Let’s look into some specific examples of strptime() function to convert string to datetime and time objects.

String to datetime

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from datetime import datetime

datetime_str = '09/19/18 13:55:26'

datetime_object = datetime.strptime(datetime_str, '%m/%d/%y %H:%M:%S')

print(type(datetime_object))
print(datetime_object)  # printed in default format

Output:

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<class 'datetime.datetime'>
2018-09-19 13:55:26

String to date object

We can use date() function alongwith strptime() function to convert string to date object.

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date_str = '09-19-2018'

date_object = datetime.strptime(date_str, '%m-%d-%Y').date()
print(type(date_object))
print(date_object)  # printed in default formatting

Output:

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<class 'datetime.date'>
2018-09-19

String to time object

We can use time() function alongwith strptime() function to convert string to time object.

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time_str = '13::55::26'
time_object = datetime.strptime(time_str, '%H::%M::%S').time()
print(type(time_object))
print(time_object)

Output:

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<class 'datetime.time'>
13:55:26

Python time strptime() example

Let’s see some examples of using time module strptime() function.

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import time

time_obj = time.strptime(time_str, '%H::%M::%S')
print(type(time_obj))
print(time_obj)

# default formatting - "%a %b %d %H:%M:%S %Y"
print(time.strptime('Wed Sep 19 14:55:02 2018'))

Output:

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<class 'time.struct_time'>
time.struct_time(tm_year=1900, tm_mon=1, tm_mday=1, tm_hour=13, tm_min=55, tm_sec=26, tm_wday=0, tm_yday=1, tm_isdst=-1)
time.struct_time(tm_year=2018, tm_mon=9, tm_mday=19, tm_hour=14, tm_min=55, tm_sec=2, tm_wday=2, tm_yday=262, tm_isdst=-1)

Python strptime() ValueError Example

We can use try-except block to catch parsing exception and perform corrective actions.

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datetime_str = '09/19/18 13:55:26'

try:
    datetime_object = datetime.strptime(datetime_str, '%m/%d/%y')
except ValueError as ve:
    print('ValueError Raised:', ve)

time_str = '99::55::26'

try:
    time_object = time.strptime(time_str, '%H::%M::%S')
except ValueError as e:
    print('ValueError:', e)

Output:

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ValueError Raised: unconverted data remains:  13:55:26
ValueError: time data '99::55::26' does not match format '%H::%M::%S'

Notice that the ValueError message clearly explains the root cause of the parsing exception.

Python Convert String to Datetime with locale

Let’s look at an example where a locale-specific string will be converted to datetime object. We will use locale module to set the locale to be used by python.

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import locale

locale.setlocale(locale.LC_ALL, 'de_DE')
date_str_de_DE = '10-Dezember-2018 Montag'  # de_DE locale
datetime_object = datetime.strptime(date_str_de_DE, '%d-%B-%Y %A')
print(datetime_object)

Output: 2018-12-10 00:00:00

References: datetime strptime(), time strptime()

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