5 Best Ways to Convert Python time to datetime

💡 Problem Formulation: In Python programming, there are frequent needs to convert time representations to datetime objects for easier manipulation and formatting. A typical case entails converting a time structure or a timestamp into a datetime object that is timezone-aware or naive, for tasks such as logging events, data analysis, or synchronization processes. For instance, you might have a timestamp in seconds since the epoch that you want to convert into a datetime object.

Method 1: Using datetime.fromtimestamp()

The datetime.fromtimestamp() function creates a datetime object from a Unix timestamp. This method is straightforward and commonly used when dealing with timestamps representing the number of seconds since the epoch, the 1st of January, 1970.

Here’s an example:

from datetime import datetime

timestamp = 1609459200
dt_object = datetime.fromtimestamp(timestamp)
print(dt_object)

Output:

2021-01-01 00:00:00

This snippet demonstrates how to convert a Unix timestamp to a datetime object. The result is a naive datetime object representing the local time that corresponds to the given timestamp.

Method 2: Using time.strptime() with datetime.combine()

A two-step process involving time.strptime() to parse a time string into a struct_time object, which is then combined with a date using datetime.combine() to form a complete datetime object. This method grants flexibility in handling different time string formats.

Here’s an example:

from datetime import datetime
import time

time_string = "23:10:00"
struct_time = time.strptime(time_string, "%H:%M:%S")
date = datetime.today()
datetime_object = datetime.combine(date, datetime.min.time()) + struct_time.tm_hour * 3600 + struct_time.tm_min * 60 + struct_time.tm_sec
print(datetime_object)

Output:

2021-01-01 23:10:00

This code parses a string representing a time into a struct_time, and then combines it with the current date to form a datetime object which includes the specified time. The time is adjusted using timedeltas for hours, minutes, and seconds.

Method 3: Using datetime.strptime()

The datetime.strptime() method is the straightforward way to convert a time string into a datetime object when the string includes both date and time information. The method parses the string based on a format specifier.

Here’s an example:

from datetime import datetime

date_string = "2021-01-01 23:10:00"
datetime_object = datetime.strptime(date_string, "%Y-%m-%d %H:%M:%S")
print(datetime_object)

Output:

2021-01-01 23:10:00

This snippet shows how a string containing date and time can be parsed into a datetime object using a specific format. This is useful for situations in which the date and time are acquired as a single string.

Method 4: Using calendar.timegm() with datetime.utcfromtimestamp()

Combining the calendar.timegm() method to convert a struct_time or broken-down time into a UTC timestamp, with datetime.utcfromtimestamp() to form a timezone-aware datetime object, is beneficial when working with UTC times.

Here’s an example:

from datetime import datetime
import calendar
import time

struct_time = time.gmtime()  # Gets current UTC struct_time
timestamp = calendar.timegm(struct_time)
utc_datetime = datetime.utcfromtimestamp(timestamp)
print(utc_datetime)

Output:

2021-01-01 23:10:00+00:00

This code first gets the current time in UTC as a struct_time, then converts it to a timestamp, and finally converts this timestamp back to a datetime object that is UTC timezone-aware.

Bonus One-Liner Method 5: Using datetime.utcnow()

As a quick bonus, if the goal is simply to obtain the current time as a naive datetime object in UTC, the built-in datetime.utcnow() function provides a one-liner solution.

Here’s an example:

from datetime import datetime

utc_now = datetime.utcnow()
print(utc_now)

Output:

2021-01-01 23:10:00.123456

This code snippet obtains the current UTC time as a naive datetime object, which does not include timezone information.

Summary/Discussion

• Method 1: Using datetime.fromtimestamp(). Simple. Suited for Unix timestamps. Timezone-naive.
• Method 2: Using time.strptime() with datetime.combine(). More complex. Flexible for different time formats. Involves more steps.
• Method 3: Using datetime.strptime(). Direct. Requires a date and time string together. Format must be specified.
• Method 4: Using calendar.timegm() with datetime.utcfromtimestamp(). Specialized for UTC. Converts struct_time to timezone-aware datetime. Intermediate UTC timestamp required.
• Bonus Method 5: Using datetime.utcnow(). Fast and efficient for current UTC time. Naive with no timezone information.