5 Best Ways to Convert Python Time to Float

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💡 Problem Formulation: Converting time into a floating-point number in Python can be essential when performing time arithmetic or logging timestamps with higher precision. This article illustrates how you can transform Python time objects, such as those from the datetime module, into floating-point numbers representing seconds since epoch or other relevant units of time. For instance, you might have a datetime object representing an event’s time, and you want to convert this to a float for timestamping logs or calculations (e.g., 2023-04-10 13:45:00 to 1678538700.0).

Method 1: Using datetime.timestamp()

This method involves using the timestamp() method available on datetime objects to obtain a UNIX timestamp in seconds as a floating-point number, which includes both the date and time information.

Here’s an example:

from datetime import datetime

my_datetime = datetime(2023, 4, 10, 13, 45)
timestamp = my_datetime.timestamp()
print(timestamp)

Output:

1678538700.0

This code snippet first creates a datetime object for April 10, 2023, at 13:45 and then converts it into a float timestamp representing the number of seconds since January 1, 1970, 00:00:00 (the UNIX epoch).

Method 2: Using time.mktime()

Another way to convert a time.struct_time object to a float is by using the time.mktime() function, which returns the time in seconds since the epoch as a floating-point number.

Here’s an example:

import time
from datetime import datetime

my_datetime = datetime(2023, 4, 10, 13, 45)
struct_time = my_datetime.timetuple()
timestamp = time.mktime(struct_time)
print(timestamp)

Output:

1678538700.0

This snippet converts a datetime object to a time.struct_time object using the timetuple() method. The time.mktime() function is then used to get the corresponding UNIX timestamp.

Method 3: Using calendar.timegm()

Utilizing calendar.timegm() is a good choice for converting a UTC time.struct_time to a POSIX timestamp. Unlike time.mktime(), which assumes local time, this function works with UTC time.

Here’s an example:

import calendar
from datetime import datetime

my_datetime = datetime(2023, 4, 10, 13, 45)
struct_time = my_datetime.utctimetuple()
timestamp = calendar.timegm(struct_time)
print(timestamp)
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Output:

1678535100.0

The above code converts a datetime object in UTC to a struct_time object with the utctimetuple() method. Then calendar.timegm() returns the equivalent UNIX timestamp.

Method 4: Manual Conversion with Custom Epoch

If you are working with a custom epoch or need a different precision, you can manually calculate the difference in seconds between your datetime and the epoch.

Here’s an example:

from datetime import datetime

custom_epoch = datetime(2000, 1, 1)
my_datetime = datetime(2023, 4, 10, 13, 45)
timestamp = (my_datetime - custom_epoch).total_seconds()
print(timestamp)

Output:

735835500.0

Here, we define a custom epoch (January 1, 2000) and subtract it from our datetime, using the total_seconds() method on the resulting timedelta object to get a floating-point timestamp.

Bonus One-Liner Method 5: Using List Comprehension and time()

For a more concise approach, you can use list comprehension along with the time() method from the datetime module to return the current time as a float directly.

Here’s an example:

from datetime import datetime

timestamp = [datetime.now().timestamp()][0]
print(timestamp)

Output:

1678538700.0

This one-liner combines list comprehension and datetime.now().timestamp() to get the current time as a float. The [0] simply extracts this single item from the list.

Summary/Discussion

  • Method 1: Using datetime.timestamp(). Straightforward, only for modern Python versions. Limited to datetime objects.
  • Method 2: Using time.mktime(). Converts struct_time object, assumes local time. Not suitable for UTC unless adjusted.
  • Method 3: Using calendar.timegm(). Good for UTC times. Requires struct_time in UTC, a bit more involved.
  • Method 4: Manual Conversion. Flexible, works with any epoch. Requires manual calculation and handling of time zones.
  • Bonus Method 5: One-Liner. Quick, elegant for current timestamps. Not versatile for different datetime objects.