# Effortlessly Convert Datetime to Seconds and Epoch Time in Python

## Epoch Time: Making Sense of Time in Python

Time is an essential aspect of our lives, and it is also crucial in programming. Programming languages like Python provide tools to manipulate time effortlessly.

One such method is Epoch Time, also called POSIX or UNIX Time, a system that provides a way of keeping track of time in seconds since January 1, 1970, called the Epoch. Many programming tasks involve calculating the time difference between two dates or finding the number of seconds elapsed between two timestamps.

We can use Python to convert datetimes to seconds and vice versa. In this article, we will explore how to convert datetime to seconds and back again in Python.

## Understanding Epoch Time

Unix Epoch time is a system that represents the number of seconds elapsed since January 1st, 1970 at 00:00:00 UTC. It is a universal standard for computers, and many operating systems use it.

To represent an Epoch Time in Python, we use a floating-point number. The floating-point number represents the number of seconds elapsed since the Epoch.

## Subtraction Method

To calculate the number of elapsed seconds between two dates, we can use the `total_seconds()` function. The `total_seconds()` function is a built-in method for datetime objects in Python.

For instance, let’s say we have two dates and we want to calculate the number of seconds between them. We can subtract the earlier date from the later date and then use the `total_seconds()` function to calculate the difference in seconds.

``````# Import datetime module
from datetime import datetime
# Date format YYYY-MM-DD HH:MM:SS
date1 = datetime.strptime('2022-01-01 01:00:00', '%Y-%m-%d %H:%M:%S')
date2 = datetime.strptime('2022-01-01 01:10:00', '%Y-%m-%d %H:%M:%S')
# Calculate the elapsed time
elapsed_time = date2 - date1
# Calculate the number of seconds
seconds_elapsed = elapsed_time.total_seconds()
# Print the result
print(f'The elapsed time between {date2} and {date1} is {seconds_elapsed} seconds')
``````

In the above example, we first import the `datetime` module and create two datetime objects. We then subtract `date1` from `date2` to get the `elapsed_time` between the two dates.

Finally, we use the `total_seconds()` function to calculate the number of seconds elapsed and print the result.

## timestamp() Method

Another way to convert datetimes to seconds is through the use of the `timestamp()` method. This method returns the number of seconds elapsed since the Epoch.

``````# Import datetime module
from datetime import datetime
# Create a datetime object
date = datetime.strptime('2022-01-01 02:00:00', '%Y-%m-%d %H:%M:%S')
# Convert to Unix Timestamp
unix_timestamp = date.timestamp()
# Print the result
print(f'The Unix Timestamp of {date} is {unix_timestamp} seconds')
``````

In the above example, we create a datetime object and use the `timestamp()` function to convert the datetime to a Unix Timestamp. We then print the result, which shows the number of seconds elapsed since the Epoch.

### Seconds/Epoch to Datetime

Conversely, we can use Python to convert Epoch time to datetimes. The `fromtimestamp()` method creates a datetime object from a Unix timestamp.

``````# Import datetime module
from datetime import datetime
# Input Unix Timestamp
unix_timestamp = 1641043200.0
# Convert to datetime object
date = datetime.fromtimestamp(unix_timestamp)
# Print the result
print(f'The datetime from Unix Timestamp {unix_timestamp} is {date}')
``````

In the above example, we use the `fromtimestamp()` method to create a datetime object from a Unix timestamp. We print the result, which shows the date and time in a formatted string.

In conclusion, Epoch Time is a universal standard for computers, and it provides a way of keeping track of time in seconds since January 1, 1970. Python provides several ways of converting datetimes to seconds, including the subtraction method and the `timestamp()` method.

Conversely, we can convert Epoch time to datetimes using the `fromtimestamp()` method. These tools enable us to work with time more efficiently and accurately in Python.

## Converting Epoch Time with Milliseconds to Datetime

In both programming and in life, time accuracy is crucial. Timestamps that represent milliseconds are commonly used for data analysis, especially for high-frequency data.

Epoch time with milliseconds refers to the number of milliseconds that elapsed since January 1st, 1970 at 00:00:00 UTC. Converting epoch time with milliseconds to datetime is essential for data manipulation or analysis, and Python provides a straightforward way of doing that.

In earlier parts of this article, we explored converting epoch time to datetime and datetime to epoch time. In this section, we will look at how to convert epoch time with milliseconds to datetime using Python.

### strptime() Method

To convert epoch time with milliseconds to a datetime object in Python, we can use the `strptime()` method. The `strptime()` method converts a string representation of the datetime object into an actual datetime object in Python.

``````# Import datetime module
from datetime import datetime
# Input Unix Timestamp in Epoch with milliseconds
epoch_milliseconds = 1641043200000
# Convert to datetime object
date = datetime.fromtimestamp(epoch_milliseconds//1000)
# Add milliseconds to datetime object
date = date.replace(microsecond=epoch_milliseconds%1000*1000)
# Print the result
print(f'The datetime from epoch with milliseconds {epoch_milliseconds} is {date}')
``````

In the above example, we first import the `datetime` module and input the Unix Timestamp in epoch with milliseconds. We then convert the Unix Timestamp to seconds by floor division by 1000 and using the `fromtimestamp()` function to create a datetime object.

Finally, we add the microseconds to the datetime object by getting the remainder of the Unix Timestamp divided by 1000 and multiplying it by 1000. The `strptime()` method requires a format code to parse the date string correctly.

In the case of epoch time with milliseconds, the `%f` format code represents the milliseconds in the string.

``````# Import datetime module
from datetime import datetime
# Input Unix Timestamp in Epoch with milliseconds
epoch_milliseconds = 1641043200000
# Convert to datetime object
date = datetime.strptime(str(epoch_milliseconds/1000), '%.3f')
# Print the result
print(f'The datetime from epoch with milliseconds {epoch_milliseconds} is {date}')
``````

In the above example, we use the `strptime()` function to convert the epoch time with milliseconds to a datetime object. We first convert the Unix Timestamp in epoch with milliseconds to seconds by dividing it by 1000 and converting it to a string.

We then use the `%.3f` format code to represent the milliseconds in the string. The `%f` code specifies the microseconds field and allows for up to six decimal places.

Thus, for epoch time with milliseconds, we can pass the string to `strptime()` with the `%f` code multiplied by 1000 to convert to microseconds.

``````# Import datetime module
from datetime import datetime
# Input Unix Timestamp in Epoch with milliseconds
epoch_milliseconds = 1641043200000
# Convert to datetime object
date = datetime.strptime(str(epoch_milliseconds), '%s%f')
# Print the result
print(f'The datetime from epoch with milliseconds {epoch_milliseconds} is {date}')
``````

In the above example, we use the `%s%f` format code to specify both the seconds and milliseconds fields. Once again, we convert the Unix Timestamp in epoch with milliseconds to a string and pass it to `strptime()` with the specified format code.

We can also write a helper function to convert epoch time with milliseconds to datetime.

``````# Import datetime module
from datetime import datetime
# Helper function to convert epoch with milliseconds to datetime
def epoch_milliseconds_to_datetime(epoch_milliseconds: int) -> datetime:
return datetime.fromtimestamp(epoch_milliseconds//1000).replace(microsecond=epoch_milliseconds%1000*1000)
# Input Unix Timestamp in Epoch with milliseconds
epoch_milliseconds = 1641043200000
# Convert to datetime object
date = epoch_milliseconds_to_datetime(epoch_milliseconds)
# Print the result
print(f'The datetime from epoch with milliseconds {epoch_milliseconds} is {date}')
``````

In the above example, we define a helper function that takes an integer input for the Unix Timestamp in epoch with milliseconds and returns a datetime object. We then use the function to convert the input epoch with milliseconds to datetime and print the result.

In conclusion, converting epoch time with milliseconds to datetime is essential for data manipulation or analysis in Python. We can use the `strptime()` method, which requires a format code to parse the date string correctly.

We can also write a helper function to convert epoch time with milliseconds to datetime. Python provides a straightforward way of converting epoch time with milliseconds to datetime, making it easy to work with high-frequency data.

In conclusion, time accuracy is crucial, especially in data analysis. Python provides powerful tools to convert datetime to seconds, seconds to datetime, and epoch time with milliseconds to datetime.

We have discussed various methods such as the subtraction method, the `timestamp()` method, and the `strptime()` method, and we have seen how to create helper functions to convert epoch time with milliseconds to datetime. Understanding these methods is essential for manipulating time data and handling high-frequency data in data analysis.

Therefore, mastering these methods will make working with time data more straightforward and efficient.