When working with datetime objects in Python, you may come across a situation where you need to append nanoseconds to a millisecond datetime object. In this article, we will explore three different ways to solve this problem.

Solution 1: Using timedelta

One way to append nanoseconds to a millisecond datetime object is by using the timedelta class from the datetime module. The timedelta class allows us to add or subtract a specific duration to a datetime object.

from datetime import datetime, timedelta

millisecond_datetime = datetime(2022, 1, 1, 12, 0, 0, 0)
nanoseconds = 500

# Convert nanoseconds to microseconds
microseconds = nanoseconds // 1000

# Create a timedelta object with microseconds
delta = timedelta(microseconds=microseconds)

# Add the timedelta to the millisecond datetime object
nanosecond_datetime = millisecond_datetime + delta

print(nanosecond_datetime)

In this solution, we first convert the given nanoseconds to microseconds by dividing it by 1000. Then, we create a timedelta object with the microseconds value. Finally, we add the timedelta to the millisecond datetime object to obtain the nanosecond datetime object.

Solution 2: Using strftime and strptime

Another way to append nanoseconds to a millisecond datetime object is by converting the datetime objects to strings, manipulating the strings, and then converting them back to datetime objects.

from datetime import datetime

millisecond_datetime = datetime(2022, 1, 1, 12, 0, 0, 0)
nanoseconds = 500

# Convert millisecond datetime to string
millisecond_str = millisecond_datetime.strftime('%Y-%m-%d %H:%M:%S.%f')

# Append nanoseconds to the millisecond string
nanosecond_str = millisecond_str[:-3] + f'{nanoseconds:03}'

# Convert nanosecond string to datetime
nanosecond_datetime = datetime.strptime(nanosecond_str, '%Y-%m-%d %H:%M:%S.%f')

print(nanosecond_datetime)

In this solution, we first convert the millisecond datetime object to a string using the strftime method. We then manipulate the string by appending the given nanoseconds. Finally, we convert the modified string back to a datetime object using the strptime method.

Solution 3: Using timedelta and total_seconds

The third way to append nanoseconds to a millisecond datetime object is by using the timedelta class and the total_seconds method. This solution involves converting both the millisecond and nanosecond datetime objects to Unix timestamps, performing the necessary calculations, and then converting the result back to a datetime object.

from datetime import datetime, timedelta

millisecond_datetime = datetime(2022, 1, 1, 12, 0, 0, 0)
nanoseconds = 500

# Convert millisecond datetime to Unix timestamp
millisecond_timestamp = millisecond_datetime.timestamp()

# Calculate nanosecond timestamp
nanosecond_timestamp = millisecond_timestamp + nanoseconds * 1e-9

# Convert nanosecond timestamp to datetime
nanosecond_datetime = datetime.fromtimestamp(nanosecond_timestamp)

print(nanosecond_datetime)

In this solution, we first convert the millisecond datetime object to a Unix timestamp using the timestamp method. We then calculate the nanosecond timestamp by adding the given nanoseconds multiplied by 1e-9 (to convert nanoseconds to seconds) to the millisecond timestamp. Finally, we convert the nanosecond timestamp back to a datetime object using the fromtimestamp method.

After evaluating the three solutions, it can be concluded that Solution 1, which uses timedelta, is the most straightforward and efficient approach to append nanoseconds to a millisecond datetime object in Python. It avoids unnecessary string conversions and provides a clear and concise solution.