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Convert string to datetime using Python strptime()

The Strptime() Method In Python

So for today, we are going to discuss how we convert a string to datetime using the Python strptime() method.

Let us get started.

Python strptime() Method

The Python strptime() method is available in both datetime and time modules. It is used to parse a given string into datetime or time object according to the specified format.

The use of this function is about the same for both the modules, the only difference being in the type of object returned. Let us have a closer look at the syntax for using it.

For the datetime module, the syntax for using the strptime() method is given below.

datetime.strptime(date_string, format)

The above statement returns a datetime object corresponding to date_string parsed according to the specified format.

And for the time module, the syntax for using the strptime() is fairly similar.

time.strptime(string[, format])

Here the method does the same job just here the returned value is a struct_time object as returned by gmtime() or localtime().

For both cases, the format parameter uses the same directives as those used by strftime() as given in the format table below. The format parameter has to be a string and has a default value "%a %b %d %H:%M:%S %Y". If the string cannot be parsed according to the given format, or if it has excess data after parsing, a ValueError is raised.

Format Table

You must follow the below-given format table to use appropriate directives while specifying the format parameter.

DirectiveMeaning of the DirectiveExample Output
%AWeekday as locale’s full name.Wednesday
%aWeekday as locale’s abbreviated name.Mon, Tue, Wed
%wWeekday as a decimal number, where 0 is Sunday and 6 is Saturday.0,1,2,3,4…6
%dDay of the month as a zero-padded decimal number.01,02,03…31
%-dDay of the month as a decimal number. (Platform specific)1,2,3…
%bMonth as locale’s abbreviated name.Mar
%BMonth as locale’s full name.March
%mMonth as a zero-padded decimal number.01,02…12
%-mMonth as a decimal number. (Platform specific)1,2,…12
%yYear without century as a zero-padded decimal number.20(for 2020)
%YYear with century as a decimal number.2020, 2021, etc.
%HHour (24-hour clock) as a zero-padded decimal number.01, 02, …
%-HHour (24-hour clock) as a decimal number. (Platform specific)1,2,3,…
%IHour (12-hour clock) as a zero-padded decimal number.01, 02, 03, …
%-IHour (12-hour clock) as a decimal number. (Platform specific)1, 2, 3 …
%pLocale’s equivalent of either AM or PM.AM, PM
%MMinute as a zero-padded decimal number.01, 02, …59
%-MMinute as a decimal number. (Platform specific)1,2,3,…59
%SSecond as a zero-padded decimal number.01, 02,…59
%-SSecond as a decimal number. (Platform specific)1, 2, …59
%fMicrosecond as a decimal number, zero-padded on the left.000000
%zUTC offset in the form +HHMM or -HHMM (empty string if the the object is naive).(empty), +0000, -0400, +1030
%ZTime zone name (empty string if the object is naive).(empty), UTC, IST, CST
%jDay of the year as a zero-padded decimal number.1, 2, 3, … 366
%-jDay of the year as a decimal number. (Platform specific)1, 2, 3, … 366
%UWeek number of the year (Sunday as the first day of the week) as a zero padded decimal number. All days in a new year preceding the first Sunday are considered to be in week 0.1, 2, 3,… 53
%WWeek number of the year (Monday as the first day of the week) as a decimal number. All days in a new year preceding the first Monday are considered to be in week 0.1, 2, 3,… 53
%cLocale’s appropriate date and time representation.Wed May 06 12:23:56 2020
%xLocale’s appropriate date representation.05/06/20
%XLocale’s appropriate time representation.12:23:56
%%A literal ‘%’ character.%
Source: Strftime() Official Homepage

Working with the strptime() Method

So now that we are familiar with the syntax of using the strptime() method for both datetime and time modules, let us see how we can use it.

1. time.strptime()

In the example below, we are going to convert a given string into a time object.

import time

time_string = "06/05/2020 12:06:58"

obj = time.strptime(time_string, "%d/%m/%Y %H:%M:%S")

print(type(obj))
print(obj)

#parsing using default formatting: %a %b %d %H:%M:%S %Y

def_obj = time.strptime("Wed May 06 12:06:58 2020")
print(def_obj)

Output:

<class 'time.struct_time'>
time.struct_time(tm_year=2020, tm_mon=5, tm_mday=6, tm_hour=12, tm_min=6, tm_sec=58, tm_wday=2, tm_yday=127, tm_isdst=-1)
time.struct_time(tm_year=2020, tm_mon=5, tm_mday=6, tm_hour=12, tm_min=6, tm_sec=58, tm_wday=2, tm_yday=127, tm_isdst=-1)

Here, time_string is the given string containing the corresponding time parameters. We parse this string using the strptime() function following the “%d/%m/%Y %H:%M:%S” format into the variable obj. As expected obj is of type time.struct_time.

Nextly, we have also parsed another string using the default formatting(without specifying the format parameter). As mentioned earlier in this case by default format is set to %a %b %d %H:%M:%S %Y . This justifies the output.

2. datetime.strptime()

Now let us use the strptime() method to convert a given string into a datetime object.

from datetime import datetime

dt_string = "06//05//2020 12:06:58"

obj = datetime.strptime(dt_string, "%d//%m//%Y %H:%M:%S")

print(type(obj))
print("DateTime object: ", obj)
print("Time object: ", obj.time())
print("Date object: ", obj.date())

Output:

Strptime Output
datetime strptime() Output

As you can see from the output above, the dt_string is successfully converted into a datetime object. We can also use the time() and date() functions over this object to get datetime.time and datetime.date objects respectively.

Let us look at another example where we take the date and time using the input() function from the user.

from datetime import datetime

dt_string = str(input("Enter date in dd:mm:yyyy format:"))

try:
    obj = datetime.strptime(dt_string, "%d:%m:%Y")
    print(obj)
    print(obj.strftime("Date:%d Month:%m Year:%Y")) #strftime to format datetime obj
except ValueError as ex:
    print("ValueError: ", ex)

Output:

Strptime Valuearror
strptime() ValueError

In this example, we take the dt_string as user input and convert it into a datetime object using the strptime() method. Again we take this object and print it is our desired format using the strftime() method.

What if we do not provide the strptime() method a string which matches to the specified format? In that case, a ValueError is raised. Look at the output below(for the same code) where we do so.

Enter date in dd:mm:yyyy format:6/5/20
ValueError:  time data '6/5/20' does not match format '%d:%m:%Y'

Summing Up

So we today learned about converting a string into various types in Python using the strptime() method.

For any further questions related to the topic feel free to use the comments below.

References