Converting Python DateTime to Unix Timestamp: Top 5 Methods

💡 Problem Formulation: Python developers often need to convert DateTime objects to Unix timestamps, which represent the number of seconds since January 1, 1970 (the Unix epoch). For instance, given a Python DateTime object datetime.datetime(2023, 1, 1, 0, 0), the desired output is the corresponding Unix timestamp 1672531200. This article explores effective ways to achieve this conversion.

Method 1: Using mktime()

One common method to convert a Python DateTime object to a Unix timestamp is using the time.mktime() function from the time module. This function takes a time tuple (which can be obtained from a DateTime object using timetuple()) and returns a Unix timestamp.

Here’s an example:

import datetime
import time

dt = datetime.datetime(2023, 1, 1, 0, 0)
timestamp = time.mktime(dt.timetuple())
print(timestamp)

Output:

1672531200.0

The code snippet above first creates a datetime object for January 1, 2023. It then calls timetuple() to convert this object to a time tuple, which is passed to time.mktime() to finally obtain the Unix timestamp.

Method 2: Using datetime.timestamp()

Introduced in Python 3.3, the datetime.timestamp() method offers a direct way to convert a DateTime object to a Unix timestamp. This method accounts for timezone information if available and returns the timestamp as a float.

Here’s an example:

import datetime

dt = datetime.datetime(2023, 1, 1, 0, 0)
timestamp = dt.timestamp()
print(timestamp)

Output:

1672531200.0

The example simply involves creating a datetime object and calling its timestamp() method to retrieve the Unix timestamp. This is one of the most straightforward methods available.

Method 3: Combining calendar.timegm() with datetime.utctimetuple()

For UTC DateTime objects, the calendar.timegm() function together with datetime.utctimetuple() provides a way to obtain Unix timestamps. The utctimetuple() generates a UTC-based time tuple which calendar.timegm() processes into a timestamp.

Here’s an example:

import datetime
import calendar

dt = datetime.datetime(2023, 1, 1, 0, 0, tzinfo=datetime.timezone.utc)
timestamp = calendar.timegm(dt.utctimetuple())
print(timestamp)

Output:

1672531200

Here, we’re working with a timezone aware DateTime object, forcing UTC, and then converting it into a timestamp using calendar.timegm() after getting the UTC time tuple with utctimetuple().

Method 4: Using strftime() to Format as Epoch Time

The strftime() method in Python’s DateTime object can format dates into strings. This can be used to format the date in a way that represents Unix epoch time by using the formatting code %s.

Here’s an example:

import datetime

dt = datetime.datetime(2023, 1, 1, 0, 0)
timestamp = dt.strftime('%s')
print(timestamp)

Output:

1672531200

The code uses strftime() with the format code %s to convert the datetime object directly into a Unix timestamp string, which is printed out. Note that this method is not available on some operating systems.

Bonus One-Liner Method 5: Subtracting Epoch

This one-liner involves calculating the total seconds by subtracting the epoch start from the DateTime object. Python allows for the subtraction of two DateTime objects directly, which results in a timedelta object. Calling total_seconds() on this delta gives us the timestamp.

Here’s an example:

import datetime

dt = datetime.datetime(2023, 1, 1, 0, 0)
epoch_start = datetime.datetime(1970, 1, 1)
timestamp = (dt - epoch_start).total_seconds()
print(timestamp)

Output:

1672531200.0

The code sets the epoch start as a DateTime object and subtracts it from the DateTime object in question. The resulting timedelta object’s total_seconds() provides the Unix timestamp.

Summary/Discussion

• Method 1: mktime(). Reliable and widely used. Rounds to the nearest integer. Time zone adjustments might be needed.
• Method 2: datetime.timestamp(). Simple and concise. Python 3.3+ only. May return a float with sub-second precision.
• Method 3: timegm() and utctimetuple(). Best for UTC DateTime objects. Requires additional imports. Not suitable for time zone aware conversions.
• Method 4: strftime(). Useful for formatting as Unix time directly. May not be supported in all environments. Returns a string, not an integer.
• Bonus Method 5: Subtracting Epoch. A straightforward one-liner. Most pythonic. May lose precision over a long time span.