time

Time Access and Conversions

The time module in Python provides functions for accessing and converting time-related data.

Epoch

The epoch is the point in time from which seconds are counted. In Python, the epoch is January 1, 1970, 00:00:00 (UTC).

Seconds Since the Epoch

The term "seconds since the epoch" refers to the total number of elapsed seconds since the epoch. This value typically excludes leap seconds.

2-Digit Years

The strptime function can parse 2-digit years when given the %y format code. These years are converted to 4-digit years based on the following rules:

Values 69--99 are mapped to 1969--1999.
Values 0--68 are mapped to 2000--2068.

Timezones

UTC (Coordinated Universal Time) is the standard time used for worldwide synchronization. DST (Daylight Saving Time) is an adjustment of the time zone by one hour during certain parts of the year.

Real-Time Functions

The precision of real-time functions (e.g., time, sleep) may be less than the units in which their values or arguments are expressed. This is because the clock may "tick" only a limited number of times per second.

Time Representations

Time can be represented in different ways in Python:

Seconds since the epoch: A floating-point number representing the total number of seconds since the epoch.
struct_time object: A tuple of nine integers representing a specific date and time.
String: A formatted representation of a date and time, such as "YYYY-MM-DD HH:MM:SS".

Conversion Functions

The time module provides functions for converting between time representations:

gmtime(seconds): Convert seconds since the epoch to a struct_time object in UTC.
localtime(seconds): Convert seconds since the epoch to a struct_time object in local time.
calendar.timegm(struct_time): Convert a struct_time object in UTC to seconds since the epoch.
mktime(struct_time): Convert a struct_time object in local time to seconds since the epoch.

Real-World Applications

The time module is used in many real-world applications, including:

Timestamping events
Tracking the duration of tasks
Scheduling events
Converting between time zones

asctime() Function

Simplified Explanation:

The asctime() function takes a time value (like the output of localtime() or gmtime()) and turns it into a human-readable string. It shows the day of the week, date, time, and year.

Topics in Detail:

1. Input:

The function can take an optional argument t, which should be a tuple or struct_time representing a time value.
If t is not provided, it uses the current time as obtained from localtime().

2. Output:

The output is a string in this format: "Day of week Month Day Hour:Minute:Second Year"
The day of the week is a two-character abbreviation, e.g., "Sun" for Sunday.
The month is a three-character abbreviation, e.g., "Jun" for June.
The day of the month is one or two digits, padded with a space if needed.
The hour, minute, and second are two digits each, padded with zeroes if needed.
The year is a four-digit number, e.g., "1993".

3. Locale Independence:

Unlike the C version of asctime(), the Python version does not use locale information to format the date. This means the output format will be consistent regardless of the system's locale settings.

Code Snippet:

import time

# Convert the current time to a time tuple
time_tuple = time.localtime()

# Convert the time tuple to a human-readable string
time_string = time.asctime(time_tuple)

# Print the time string
print(time_string)

Output:

Sun Jun 20 23:21:05 1993

Real-World Applications:

Displaying dates and times in user interfaces
Creating log files with timestamps
Parsing time values in automated scripts
Converting dates between different formats

pthread_getcpuclockid

Purpose:

Determine the clock identifier (clk_id) of the thread-specific CPU-time clock for a given thread.

How it works:

Every thread in a multi-threaded program has its own CPU time clock. This clock measures the amount of time the thread has spent executing on the CPU.

You can obtain the clk_id of a thread's CPU time clock using pthread_getcpuclockid(). This value can then be used to access and manipulate the thread's CPU time information.

Usage:

To use pthread_getcpuclockid(), you need to pass it the ID of the thread you want to get the clk_id for. The thread ID can be obtained using threading.get_ident() or the ident attribute of a threading.Thread object.

Here's an example:

import threading

def get_cpu_clock_id(thread_id):
    clk_id = pthread_getcpuclockid(thread_id)
    return clk_id

# Get the current thread's ID
current_thread_id = threading.get_ident()

# Get the CPU clock ID for the current thread
cpu_clock_id = get_cpu_clock_id(current_thread_id)

Real-world application:

pthread_getcpuclockid() can be useful in debugging and performance analysis. By accessing the CPU time information of a thread, you can determine how much time the thread has spent executing and identify potential performance bottlenecks.

clock_getres()

Explanation:

The clock_getres() function tells you how precise a specific clock is.

Parameters:

clk_id: A number that tells which clock you want to ask about.

Return Value:

A number that tells you how many nanoseconds between each tick of the clock.

Real-World Example:

Here's a simple example Python code:

import time
import timeit

res = time.clock_getres(time.CLOCK_PROCESS_CPUTIME_ID)

print(res)
# Output: 1.0e-06

In this example, we ask about the precision of the clock that measures how much time the current process spent running. The output is 1 microsecond (10^-6 seconds), which means that the clock can measure time with accuracy up to 1 microsecond.

Potential Applications:

Measuring how long a specific task takes to execute.
Synchronizing tasks across multiple processes.
Debugging performance issues.

Clock functions:

clock() returns the current CPU time in seconds.
time() returns the current time in seconds since the epoch.
clock_gettime() returns the time of a specific clock, such as the real-time clock or the monotonic clock.

Monotonic Clock: The monotonic clock is a non-decreasing clock that measures time intervals regardless of system changes, such as the adjustment of the system clock. This makes it useful for applications that need to measure time intervals accurately, such as profiling and synchronization.

Example usage:

import time

# Get current CPU time in seconds
cpu_time = time.clock()

# Get current time in seconds since the epoch
current_time = time.time()

# Get time of real-time clock in seconds since the epoch
real_time = time.clock_gettime(time.CLOCK_REALTIME)

# Get time of monotonic clock in seconds since the epoch
mono_time = time.clock_gettime(time.CLOCK_MONOTONIC)

Real-World Applications:

CPU Time:

Profiling: Measuring the execution time of different parts of a program.
Resource monitoring: Tracking CPU usage over time.

Time Since Epoch:

Date and time display: Converting timestamps to human-readable formats.
Time-based calculations: Calculating time differences, such as elapsed time or expiration dates.

Monotonic Clock:

Synchronization: Coordinating multiple processes or devices without relying on system clock changes.
Performance measurement: Measuring time intervals without interference from system clock adjustments.

Function: clock_gettime_ns

Purpose: Get the current time in nanoseconds.

Syntax:

clock_gettime_ns(clk_id) -> int

Arguments:

clk_id: The clock ID (e.g., time.CLOCK_REALTIME for the system clock).

Returns:

The current time in nanoseconds since the epoch (January 1, 1970 at midnight UTC).

Example:

import time

# Get the current time in nanoseconds
now = time.clock_gettime_ns(time.CLOCK_REALTIME)

# Print the time in a human-readable format
print(time.ctime(now / 1000000000))

Output:

Tue Sep 20 17:03:01 2022

Applications:

Measuring the performance of code
Generating timestamps for events
Scheduling tasks

clock_settime() Function

Explanation

The clock_settime() function lets you change the time of a specific clock in your computer. This can be useful for setting your system clock or for testing code that relies on the current time.

Parameters

The clock_settime() function takes two parameters:

clk_id: A constant that tells the function which clock you want to change. Currently, the only accepted value for clk_id is CLOCK_REALTIME, which refers to the system clock.
time: A floating-point number representing the new time you want to set the clock to. The time is measured in seconds.

Example

Here's an example of how to use the clock_settime() function:

import time

# Get the current time
current_time = time.time()

# Set the time to 1 hour earlier
new_time = current_time - 3600

# Change the time of the system clock
time.clock_settime(time.CLOCK_REALTIME, new_time)

# Verify that the time has changed
print(time.time())

Real-World Applications

The clock_settime() function can be used for a variety of purposes, including:

Setting your system clock. If your computer's clock is incorrect, you can use the clock_settime() function to fix it.
Testing code that relies on the current time. If you're writing code that relies on the current time, you can use the clock_settime() function to test your code with different time values.

clock_settime_ns() Function

Explanation

The clock_settime_ns() function is similar to the clock_settime() function, but it allows you to set the time of a clock with more precision. The time is measured in nanoseconds, which is 1 billionth of a second.

Parameters

The clock_settime_ns() function takes two parameters:

clk_id: A constant that tells the function which clock you want to change. Currently, the only accepted value for clk_id is CLOCK_REALTIME, which refers to the system clock.
time: A tuple of two integers representing the new time you want to set the clock to. The first integer is the seconds part of the time, and the second integer is the nanoseconds part of the time.

Example

Here's an example of how to use the clock_settime_ns() function:

import time

# Get the current time
current_time = time.time()

# Set the time to 1 nanosecond earlier
new_time = (int(current_time), int(current_time * 1000000000) - 1)

# Change the time of the system clock
time.clock_settime_ns(time.CLOCK_REALTIME, new_time)

# Verify that the time has changed
print(time.time())

Real-World Applications

The clock_settime_ns() function can be used for a variety of purposes, including:

Precision timing. If you need to measure time very accurately, you can use the clock_settime_ns() function to set the time of the system clock to a specific value.
Testing code that relies on the current time. If you're writing code that relies on the current time, you can use the clock_settime_ns() function to test your code with different time values.

Function: clock_settime_ns

Simplified Explanation:

Imagine your computer has multiple clocks, like a kitchen timer for cooking and a stopwatch for running. clock_settime_ns lets you adjust the time shown on one of these clocks.

Technical Details:

clk_id specifies which clock you want to adjust (e.g., CLOCK_REALTIME for the system clock).
time is the new time to set in nanoseconds (billionths of a second).

Real-World Example:

You're developing a video game and want to make sure the game runs at a consistent speed. You can use clock_settime_ns to adjust the system clock so that each frame of the game takes exactly the same amount of time.

Code Implementation:

import time

# Get the current system time
current_time = time.clock_gettime(time.CLOCK_REALTIME)

# Convert the current time to nanoseconds
current_nanoseconds = current_time.tv_sec * 1000000000 + current_time.tv_nsec

# Add 100 nanoseconds to the current time
new_time = current_nanoseconds + 100

# Set the system time to the new time
time.clock_settime_ns(time.CLOCK_REALTIME, new_time)

Potential Applications:

Synchronizing clocks across multiple computers in a network
Creating high-precision timing applications (e.g., financial trading)
Debugging timing issues in code

ctime() Function

Description:

The ctime() function converts a timestamp (number of seconds since January 1, 1970) into a human-readable string representing the local time.

Parameters:

secs (optional): The timestamp to convert. If not provided, the current time is used.

Return Value:

A string representing the local time in the format:

'Day Name Month Day HH:MM:SS Year'

Example Usage:

import time

# Get current time as a timestamp
timestamp = time.time()

# Convert timestamp to local time string
local_time = time.ctime(timestamp)

# Print the local time
print(local_time)

Output:

Sun Jun 20 23:21:05 1993

Real-World Applications:

Storing timestamps in databases for tracking events
Displaying time information in user interfaces
Comparing timestamps to determine age or duration of events
Setting time-based limits or constraints
Logging events with timestamps for debugging or security purposes

get_clock_info() Function

This function provides information about a specified clock in a Python program.

Understanding Clocks in Python

In Python, there are several different types of clocks:

Monotonic Clock: Measures time elapsed since an arbitrary starting point, and never goes backward.
Performance Counter Clock: Measures time elapsed since an arbitrary starting point, but can be affected by power saving modes.
Process Time Clock: Measures CPU time spent by the current process.
Thread Time Clock: Measures CPU time spent by the current thread.
System Time Clock: Measures the current time based on the system's clock, influenced by factors like time zone and NTP synchronization.

Using get_clock_info()

The get_clock_info() function takes one parameter:

name: The name of the clock to get information about, as a string.

The function returns a namespace object with the following attributes:

adjustable: True if the clock can be changed manually or automatically, False otherwise.
implementation: The name of the underlying C function used to get the clock value.
monotonic: True if the clock cannot go backward, False otherwise.
resolution: The resolution of the clock in seconds (a float).

Code Example

import time

# Get information about the monotonic clock
clock_info = time.get_clock_info('monotonic')

# Print the clock information
print(clock_info.adjustable)  # True or False
print(clock_info.implementation)  # Name of the underlying C function
print(clock_info.monotonic)  # True
print(clock_info.resolution)  # Resolution in seconds

Real-World Applications

Measuring execution time: The monotonic and performance counter clocks can be used to measure the execution time of code blocks.
Synchronizing events: Clocks that are guaranteed to be monotonic can be used to ensure that events occur in a specific order.
Evaluating system performance: Process and thread time clocks can be used to evaluate the performance of a process or thread.
Time-based calculations: Clocks can be used for calculations such as time differences and timeouts.

gmtime() function

The gmtime() function in Python's time module converts a timestamp (the number of seconds since the start of the Unix epoch, which is January 1, 1970 at midnight UTC) into a struct_time object. A struct_time object is a named tuple containing the following fields:

(year, month, day, hour, minute, second, weekday, yearday, isdst)

The isdst field is always 0 for gmtime() because it returns a time in UTC, which does not observe daylight saving time.

Example:

import time

timestamp = time.time()
struct_time = time.gmtime(timestamp)

print(struct_time)

Output:

time.struct_time(tm_year=2023, tm_mon=3, tm_mday=14, tm_hour=19, tm_min=35, tm_sec=32, tm_wday=2, tm_yday=73, tm_isdst=0)

Applications:

The gmtime() function is useful for converting timestamps to UTC times, which can be helpful for debugging, logging, and other tasks. It can also be used to create time series data in UTC, which can be helpful for data analysis and visualization.

localtime() Function in Python's time Module

Purpose:

The localtime() function returns a tuple with nine elements representing the local date and time, adjusted for daylight saving time if applicable.

Syntax:

localtime([secs])

Parameters:

secs (optional): A timestamp in seconds since the epoch (January 1, 1970 at midnight UTC). If not provided, the current time is used.

Return Value:

A tuple with the following elements:

Year (4 digits)
Month (1-12)
Day of the month (1-31)
Hour (0-23)
Minute (0-59)
Second (0-59)
Weekday (0-6, where 0 is Monday)
Day of the year (1-366)
Daylight saving flag (1 if DST is active, 0 otherwise)

Simplified Explanation:

Imagine time as a giant ruler stretching from the past to the future. Each second is marked by a number on the ruler. localtime() takes a number representing a position on the ruler and converts it into a readable date and time, taking into account where you are in the world and whether it's daylight saving time.

Real-World Implementation:

import time

# Get the current local date and time
localtime = time.localtime()

# Print the individual elements
print("Year:", localtime[0])
print("Month:", localtime[1])
print("Day:", localtime[2])
print("Hour:", localtime[3])
print("Minute:", localtime[4])
print("Second:", localtime[5])
print("Weekday:", localtime[6])
print("Day of the year:", localtime[7])
print("DST flag:", localtime[8])

Potential Applications:

Displaying local dates and times in applications
Scheduling tasks based on local time
Converting timestamps to a human-readable format
Adjusting for daylight saving time

mktime() Function

Purpose:

The mktime() function in Python's time module converts a local time represented by a struct_time object or a full 9-tuple into a floating-point number representing the epoch time in seconds.

Parameters:

t: A struct_time object or a 9-tuple representing the local time. The tuple should contain the time components in the following order:

(year, month, day, hour, minute, second, weekday, Julian day, DST flag)

Return Value:

A floating-point number representing the epoch time in seconds.

Usage:

import time

# Create a struct_time object
local_time = time.localtime()

# Convert local time to epoch time
epoch_time = time.mktime(local_time)

print(epoch_time)

Output:

1651546132.985693

Real-World Applications:

Convert local time to epoch time for storage in a database.
Calculate time differences between two local time intervals.
Schedule events or tasks based on local time.

Simplified Explanation:

Imagine you have a clock that shows the time in your local timezone. The mktime() function converts the time displayed on this clock into a number that represents how many seconds have passed since a specific date and time in the past (known as the "epoch"). This number can be used for various purposes, such as calculating time differences or scheduling events.

Improved Code Example:

import time

# Create a struct_time object for a specific date and time
local_time = time.struct_time((2023, 9, 14, 17, 25, 57, 3, 258, -1))

# Convert local time to epoch time
epoch_time = time.mktime(local_time)

# Print the epoch time
print(epoch_time)

Output:

1663166357.0

This improved example demonstrates how to create a struct_time object with a specific date and time and then convert it to epoch time. The epoch time represents the number of seconds that have passed since January 1, 1970, at 00:00:00 Coordinated Universal Time (UTC).

monotonic() Function

The monotonic() function in Python returns the value of a monotonic clock in fractional seconds. A monotonic clock is a clock that cannot go backwards, and its value is not affected by system clock updates.

Simplified Explanation:

Imagine you are timing a race. You have a stopwatch that starts at 0.00 seconds. As the race progresses, the stopwatch keeps counting up, always showing the elapsed time. However, if you accidentally press the reset button, the stopwatch goes back to 0.00 seconds.

A monotonic clock is like a stopwatch that never resets. Even if you accidentally change the system clock, the monotonic clock keeps counting up. This makes it useful for measuring time intervals where you need to know the elapsed time, but you don't care about the exact time of day.

Code Snippet:

import time

# Get the current monotonic time
start_time = time.monotonic()

# Do something that takes time
for i in range(1000000):
    pass

# Get the elapsed time
elapsed_time = time.monotonic() - start_time

# Print the elapsed time
print("Elapsed time:", elapsed_time)

Output:

Elapsed time: 0.0002399999997486266

Real-World Applications:

Performance profiling: Measuring the time it takes for a function or code block to execute.
Game development: Measuring the frame time and ensuring a consistent framerate.
Scientific research: Measuring the time it takes for experiments to complete.
Benchmarking: Comparing the performance of different algorithms or systems.

Note: On macOS, the monotonic() function is system-wide, meaning it returns the same value for all processes on the system. On other platforms, it is process-specific.

monotonic_ns() Function

Simplified Explanation:

The monotonic_ns() function returns the current time as a number of nanoseconds since an arbitrary point in the past. Nanoseconds are billionths of a second, making this function very precise.

Detailed Explanation:

Unlike the time.time() function, monotonic_ns() is not affected by system clock changes or daylight saving time adjustments. This means it always provides a steady and increasing value over time, regardless of any external factors.

Syntax:

import time

current_time_ns = time.monotonic_ns()

Return Value:

The function returns an integer representing the current time in nanoseconds.

Real-World Example:

Imagine you have a program that needs to measure the execution time of a certain task. By calling monotonic_ns() before and after executing the task, you can calculate the elapsed time with high precision, even if the system clock changed during the execution.

Code Implementation:

import time

start_time_ns = time.monotonic_ns()
# Execute the task here
end_time_ns = time.monotonic_ns()

elapsed_time_ns = end_time_ns - start_time_ns
elapsed_time_ms = elapsed_time_ns / 1000000  # Convert to milliseconds

print("Elapsed time:", elapsed_time_ms, "milliseconds")

Potential Applications:

Measuring performance and execution times
Timing events in high-frequency trading
Monitoring application responsiveness
Creating precise time-based events or notifications

What is perf_counter()?

perf_counter() is a Python function that measures how long it takes for your code to run. It's like a stopwatch that starts when you call the function and stops when you call it again.

How does perf_counter() work?

perf_counter() uses the highest-resolution clock available on your computer to measure time. This means it can measure even very short amounts of time, such as a few millionths of a second.

Why use perf_counter()?

You can use perf_counter() to:

Find out how long specific parts of your code take to run.
Optimize your code by making it run faster.
Compare the performance of different algorithms or code implementations.

Real-world example:

Here's a simple example of how to use perf_counter():

import time

start_time = time.perf_counter()
# Do something that takes time
end_time = time.perf_counter()

print("It took", end_time - start_time, "seconds to run the code.")

Potential applications:

perf_counter() can be used in a variety of real-world applications, such as:

Profiling code to find bottlenecks
Optimizing algorithms
Comparing the performance of different software or hardware implementations
Measuring the latency of network connections

Function: perf_counter_ns()

Simplified Explanation:

Imagine you have a super-fast clock that measures time way smaller than even a millisecond. perf_counter_ns() gives you the current time measured by this ultra-precise clock in nanoseconds.

Code Snippet:

import time
start_time = time.perf_counter_ns()  # Get the current time in nanoseconds
# Do something
end_time = time.perf_counter_ns()  # Get the current time again in nanoseconds
duration = end_time - start_time  # Calculate the time it took in nanoseconds
print(duration)

Real-World Applications:

Performance Benchmarking: Measuring the time it takes for a piece of code to execute helps optimize for speed and efficiency.
Gaming: In fast-paced games, the time between frames or player actions can make a big difference. perf_counter_ns() can help analyze and improve gameplay performance.
Scientific Research: Nanosecond-level precision allows for detailed analysis of physical phenomena and high-speed processes.

process_time() function is used to measure the amount of time spent by the current process in executing. It returns the value of the sum of the system and user CPU time of the current process. The system CPU time is the time spent by the process in the kernel. The user CPU time is the time spent by the process in user mode.

The process_time() function is process-wide by definition. This means that it measures the time spent by all threads in the process. It does not include time elapsed during sleep or time waiting for input/output operations.

The reference point of the returned value is undefined, so that only the difference between the results of two calls is valid. This means that you cannot compare the value returned by process_time() to a known value, such as the current time. You can only compare the values returned by two calls to process_time() to determine how much time has elapsed between the two calls.

The process_time() function is useful for benchmarking code. By measuring the time spent executing a block of code, you can determine how efficient the code is. You can also use the process_time() function to track the time spent in different parts of your program.

Here is an example of how to use the process_time() function:

import time

start_time = time.process_time()

# Do something

end_time = time.process_time()

print("Time elapsed:", end_time - start_time)

In this example, the process_time() function is used to measure the time spent executing the do something block of code. The start_time variable is assigned the value of the process_time() function before the block of code is executed. The end_time variable is assigned the value of the process_time() function after the block of code is executed. The difference between the end_time and start_time variables is the amount of time spent executing the block of code.

The process_time() function can be used in a variety of real-world applications. Here are a few examples:

Benchmarking code: The process_time() function can be used to benchmark code to determine how efficient it is.
Tracking the time spent in different parts of a program: The process_time() function can be used to track the time spent in different parts of a program to identify bottlenecks.
Monitoring the performance of a system: The process_time() function can be used to monitor the performance of a system to identify performance issues.

What is process_time_ns()?

process_time_ns() is a function in Python that returns the amount of time that the current process has spent executing in nanoseconds.

How does it work?

When you run a Python program, the operating system creates a new process for it. This process is a collection of resources, such as memory, CPU time, and file handles, that the program needs to run.

process_time_ns() measures the amount of CPU time that the current process has spent executing. This includes the time spent running the program's code, as well as the time spent waiting for input or output from the operating system.

Why is it useful?

process_time_ns() can be useful for a variety of purposes, such as:

Profiling: Measuring the amount of time that a program spends executing can help you identify bottlenecks and optimize your code.
Benchmarking: Comparing the performance of different programs or algorithms can help you choose the best option for your needs.
Monitoring: Tracking the performance of a program over time can help you identify potential problems.

How to use it:

To use process_time_ns(), simply call the function. It will return the amount of time that the current process has spent executing in nanoseconds.

import time

start_time = time.process_time_ns()

# Do some work

end_time = time.process_time_ns()

print("The program took", end_time - start_time, "nanoseconds to run.")

Real-world examples:

Here are a few real-world examples of how process_time_ns() can be used:

Profiling a web server: You can use process_time_ns() to measure the amount of time that a web server spends processing requests. This information can help you identify bottlenecks and optimize your server configuration.
Benchmarking sorting algorithms: You can use process_time_ns() to compare the performance of different sorting algorithms. This information can help you choose the best algorithm for your needs.
Monitoring a long-running process: You can use process_time_ns() to track the performance of a long-running process, such as a data analysis job. This information can help you identify potential problems and ensure that the process is running smoothly.

sleep() Function

The sleep() function in Python's time module allows you to pause the execution of your program for a specified number of seconds. It's like taking a nap!

How to Use sleep()

To use sleep(), simply pass it the number of seconds you want to pause for as an argument:

import time

# Pause execution for 5 seconds
time.sleep(5)

You can also pass a floating-point number to specify a more precise sleep time, such as 0.5 for half a second.

What Happens When You Use sleep()

When you call sleep(), your program will stop executing the next line of code for the specified number of seconds. This can be useful for:

Adding delays between actions or tasks
Simulating real-world scenarios, such as waiting for a response from a server
Creating animations or other visual effects

Real-World Examples

A game developer might use sleep() to create a pause between levels.
A data scientist might use sleep() to wait for a database query to finish before processing the results.
A UI designer might use sleep() to create a fade-in effect for a website element.

Note:

The actual sleep time may be slightly longer than requested due to the nature of the underlying operating system.
If the sleep is interrupted by a signal (such as a keyboard interrupt), an exception may be raised.
On Windows systems, the default resolution for sleep() is around 15 milliseconds.

ERROR OCCURED

.. function:: strftime(format[, t])

Convert a tuple or :class:struct_time representing a time as returned by :func:gmtime or :func:localtime to a string as specified by the format argument. If t is not provided, the current time as returned by :func:localtime is used. format must be a string. :exc:ValueError is raised if any field in t is outside of the allowed range.

0 is a legal argument for any position in the time tuple; if it is normally illegal the value is forced to a correct one.

The following directives can be embedded in the format string. They are shown without the optional field width and precision specification, and are replaced by the indicated characters in the :func:strftime result:

+-----------+------------------------------------------------+-------+ | Directive | Meaning | Notes | +===========+================================================+=======+ | %a | Locale's abbreviated weekday name. | | | | | | +-----------+------------------------------------------------+-------+ | %A | Locale's full weekday name. | | +-----------+------------------------------------------------+-------+ | %b | Locale's abbreviated month name. | | | | | | +-----------+------------------------------------------------+-------+ | %B | Locale's full month name. | | +-----------+------------------------------------------------+-------+ | %c | Locale's appropriate date and time | | | | representation. | | +-----------+------------------------------------------------+-------+ | %d | Day of the month as a decimal number [01,31]. | | | | | | +-----------+------------------------------------------------+-------+ | %H | Hour (24-hour clock) as a decimal number | | | | [00,23]. | | +-----------+------------------------------------------------+-------+ | %I | Hour (12-hour clock) as a decimal number | | | | [01,12]. | | +-----------+------------------------------------------------+-------+ | %j | Day of the year as a decimal number [001,366]. | | | | | | +-----------+------------------------------------------------+-------+ | %m | Month as a decimal number [01,12]. | | | | | | +-----------+------------------------------------------------+-------+ | %M | Minute as a decimal number [00,59]. | | | | | | +-----------+------------------------------------------------+-------+ | %p | Locale's equivalent of either AM or PM. | (1) | | | | | +-----------+------------------------------------------------+-------+ | %S | Second as a decimal number [00,61]. | (2) | | | | | +-----------+------------------------------------------------+-------+ | %U | Week number of the year (Sunday as the first | (3) | | | day of the week) as a decimal number [00,53]. | | | | All days in a new year preceding the first | | | | Sunday are considered to be in week 0. | | | | | | | | | | | | | | +-----------+------------------------------------------------+-------+ | %w | Weekday as a decimal number [0(Sunday),6]. | | | | | | +-----------+------------------------------------------------+-------+ | %W | Week number of the year (Monday as the first | (3) | | | day of the week) as a decimal number [00,53]. | | | | All days in a new year preceding the first | | | | Monday are considered to be in week 0. | | | | | | | | | | | | | | +-----------+------------------------------------------------+-------+ | %x | Locale's appropriate date representation. | | | | | | +-----------+------------------------------------------------+-------+ | %X | Locale's appropriate time representation. | | | | | | +-----------+------------------------------------------------+-------+ | %y | Year without century as a decimal number | | | | [00,99]. | | +-----------+------------------------------------------------+-------+ | %Y | Year with century as a decimal number. | | | | | | +-----------+------------------------------------------------+-------+ | %z | Time zone offset indicating a positive or | | | | negative time difference from UTC/GMT of the | | | | form +HHMM or -HHMM, where H represents decimal| | | | hour digits and M represents decimal minute | | | | digits [-23:59, +23:59]. [1]_ | | +-----------+------------------------------------------------+-------+ | %Z | Time zone name (no characters if no time zone | | | | exists). Deprecated. [1]_ | | +-----------+------------------------------------------------+-------+ | %% | A literal '%' character. | | +-----------+------------------------------------------------+-------+

Notes:

(1) When used with the :func:strptime function, the %p directive only affects the output hour field if the %I directive is used to parse the hour.

.. _leap-second:

(2) The range really is 0 to 61; value 60 is valid in timestamps representing leap seconds_ and value 61 is supported for historical reasons.

(3) When used with the :func:strptime function, %U and %W are only used in calculations when the day of the week and the year are specified.

Here is an example, a format for dates compatible with that specified in the :rfc:2822 Internet email standard. [1]_ ::

  >>> from time import gmtime, strftime
  >>> strftime("%a, %d %b %Y %H:%M:%S +0000", gmtime())
  'Thu, 28 Jun 2001 14:17:15 +0000'

Additional directives may be supported on certain platforms, but only the ones listed here have a meaning standardized by ANSI C. To see the full set of format codes supported on your platform, consult the :manpage:strftime(3) documentation.

On some platforms, an optional field width and precision specification can immediately follow the initial '%' of a directive in the following order; this is also not portable. The field width is normally 2 except for %j where it is 3.

.. index:: single: % (percent); datetime format

Can you please simplify and explain the given content from python's time module?

explain each topic in detail and simplified manner (simplify in very plain english like explaining to a child).
retain code snippets or provide if you have better and improved versions or examples.
give real world complete code implementations and examples for each.
provide potential applications in real world for each.
ignore version changes, changelogs, contributions, extra unnecessary content.
```
  The response was blocked.
```

strptime

What is it?

strptime is a function that parses a string representing a time into a struct_time object, similar to what is returned by gmtime or localtime.

How to use it?

You pass two arguments to strptime:

A string representing the time
A format string specifying how the time should be parsed

The format string uses the same directives as those used by strftime. For example, "%a %b %d %H:%M:%S %Y" matches the formatting returned by ctime.

What if the string can't be parsed?

If the string cannot be parsed according to the format, or if it has excess data after parsing, strptime will raise a ValueError exception.

What if some data is missing?

If some data is missing from the string, strptime will fill in default values. The default values are (1900, 1, 1, 0, 0, 0, 0, 1, -1), which represent the following:

Year: 1900
Month: January
Day: 1
Hour: 0
Minute: 0
Second: 0
Weekday: Monday
Julian day: 1
Daylight saving time: -1 (unknown)

Example:

The following code parses the string "30 Nov 00" using the format string "%d %b %y":

import time

time_string = "30 Nov 00"
format_string = "%d %b %y"
time_struct = time.strptime(time_string, format_string)

print(time_struct)

Output:

time.struct_time(tm_year=2000, tm_mon=11, tm_mday=30, tm_hour=0, tm_min=0,
                       tm_sec=0, tm_wday=3, tm_yday=335, tm_isdst=-1)

Real-world applications:

strptime is useful for converting strings representing times into struct_time objects, which can then be used to perform various date and time operations. For example, you could use strptime to:

Convert a string representing a birthdate into a struct_time object, which can then be used to calculate the person's age.
Convert a string representing a time zone into a struct_time object, which can then be used to adjust the time for a different time zone.
Convert a string representing a time interval into a struct_time object, which can then be used to add or subtract time from a given date.

Explanation

The struct_time class is a named tuple that represents a time value sequence, such as those returned by the gmtime(), localtime(), and strptime() functions. These functions are used to convert a time value from a specific format, such as a Unix timestamp, to a human-readable format.

Index The index of the attribute in the struct_time object.
Attribute The name of the attribute.
Values The possible values for the attribute.

The following table shows the attributes and their corresponding values:

Index

Attribute

Values

tm_year

The year as a four-digit integer.

tm_mon

The month as a one-digit integer.

tm_mday

The day of the month as a one-digit integer.

tm_hour

The hour as a one-digit integer.

tm_min

The minute as a one-digit integer.

tm_sec

The second as a one-digit integer.

tm_wday

The day of the week as a one-digit integer (0-6, where 0 is Monday).

tm_yday

The day of the year as a one-digit integer (0-364).

tm_isdst

If daylight saving time is in effect, this attribute is 1; otherwise, it is 0.

Real-World Example

The following code snippet shows how to use the gmtime() function to convert a Unix timestamp to a struct_time object:

import time

timestamp = time.time()
struct_time = time.gmtime(timestamp)

print(struct_time)

Output:

time.struct_time(tm_year=2023, tm_mon=2, tm_mday=14, tm_hour=15, tm_min=30, tm_sec=45, tm_wday=2, tm_yday=44, tm_isdst=0)

Potential Applications

The struct_time class can be used in a variety of applications, including:

Displaying the current time and date in a human-readable format.
Parsing dates and times from text input.
Converting between different time formats.
Scheduling tasks.
Timekeeping in scientific and engineering applications.

tm_year

Description: The tm_year attribute of a time object represents the year as a number (e.g., 1993).

Example:

import time

t = time.localtime()
print(t.tm_year)  # Output: 2023

Real-World Application:

Displaying the current year in a calendar or date picker.
Calculating the age of a person based on their birth year.
Comparing dates to determine the difference in years.

tm_mon Attribute

- Range: [1, 12]

Meaning: Represents the month number, where 1 is January and 12 is December.

- Code Example:

import time

t = time.localtime()
print(t.tm_mon)  # Output: 5 (May)

Applications:

Determining the current month or setting a specific month in a datetime object.
Analyzing historical data by month (e.g., sales figures, weather patterns).

Simplified Explanation:

Imagine a calendar with 12 months, numbered from 1 to 12. The tm_mon attribute tells you which month you're currently in or the month you want to set.

Attribute: tm_day

Description: Represents the day of the month, ranging from 1 to 31.
Example:

import time

# Get the current time
now = time.localtime()

# Print the day of the month
print(now.tm_day)

Simplified Explanation:

tm_day is like the number on a calendar that tells you which day it is in the month. For example, if today is July 10th, tm_day will be 10.

Real-World Application:

Displaying the current day of the month on a digital clock or website.
Calculating how many days are left until a specific date.
Managing bookings and reservations that occur on specific days of the month.

tm_hour Attribute:

Definition: Represents the hour of the day, ranging from 0 to 23.
Range: [0, 23]
Example:

from time import localtime

# Get the current time
t = localtime()

# Access the tm_hour attribute
hour = t.tm_hour

Real-World Applications:

Displaying the current time in a user interface
Scheduling tasks or appointments
Tracking time spent on certain activities

The tm_min attribute in the time module represents the minute of the hour, ranging from 0 to 59.

Real-World Example:

import time

# Get the current time as a time object
current_time = time.localtime()

# Print the minute of the hour
print(current_time.tm_min)

This code snippet will output the current minute of the hour, for example:

Potential Applications in the Real World:

The tm_min attribute can be used in many real-world applications, such as:

Scheduling tasks to run at specific times
Tracking the time spent on different activities
Displaying the current time in a user-friendly format

Code Implementation:

The following code snippet shows how to use the tm_min attribute to schedule a task to run at a specific time:

import time
import sched

# Create a scheduler object
scheduler = sched.scheduler(time.time, time.sleep)

# Schedule a task to run at 10:15 AM
scheduler.enterabs(time.mktime((2023, 5, 1, 10, 15, 0, 0, 0, -1)), 1, print, ("Task 1"))

# Run the scheduler
scheduler.run()

This code snippet will schedule the print function to be executed at 10:15 AM on May 1, 2023.

time.tm_sec

Simplified Explanation

tm_sec is an attribute of the time module that represents the seconds field of a time object. It is a number between 0 and 61, where 61 is used to represent leap seconds.

Technical Explanation

Leap seconds are an occasional adjustment made to the Coordinated Universal Time (UTC) clock to keep it in sync with the Earth's rotation. Normally, a day has 86,400 seconds, but leap seconds are added or removed to account for slight variations in the Earth's rotation.

Real-World Example

The following code snippet shows how to get the seconds field of a time object:

import time

# Get the current time
now = time.localtime()

# Get the seconds field
seconds = now.tm_sec

# Print the seconds
print(seconds)

This code will output the current number of seconds.

Potential Applications

tm_sec can be used in a variety of applications, such as:

Displaying the current time
Calculating the time difference between two events
Scheduling tasks

tm_wday attribute explained:

What it is:
- tm_wday is a field within the time struct that represents the day of the week.
Range:
- It ranges from 0 to 6, where:
  - 0 = Monday
  - 1 = Tuesday
  - 2 = Wednesday
  - 3 = Thursday
  - 4 = Friday
  - 5 = Saturday
  - 6 = Sunday
Example:
- If the current date is Wednesday, then tm_wday will be 2.
Code snippet:

import time

now = time.localtime()
print(now.tm_wday)  # Output: 2 for Wednesday

Real-world applications:

Scheduling events: Applications can use tm_wday to schedule events on specific days of the week, such as sending out weekly newsletters or reminders.
Calendar display: tm_wday is useful for creating calendar displays that show the days of the week in the correct order.
Date validation: Applications can use tm_wday to validate dates to ensure that they are valid. For example, an application can use tm_wday to check if a date falls on a weekend.

Attribute: tm_yday

Purpose: Represents the day of the year (1-366)

Range: [1, 366]

Simplified Explanation:

Imagine a calendar with 366 days, including leap days. The tm_yday attribute tells you which day of the year it is, starting from 1 on January 1st and ending on 366 on December 31st.

Code Snippets:

from time import strftime

# Get the current day of the year
current_day_of_year = strftime("%j")  # Returns a string representation of the day of the year (e.g., '089')

Real-World Applications:

Calculating birthdays or anniversaries within a year
Determining the day of the week for a given date (using the formula weekday = (day_of_year - 1) % 7)
Scheduling events based on specific days of the year (e.g., holidays)

tm_isdst Attribute

Definition: Represents whether daylight saving time (DST) is active for the given time.
Values:
- 0: DST is not active.
- 1: DST is active.
- -1: DST information is not available.

Simpler Explanation:

Imagine time as a clock. Daylight saving time is like when you move the hands of a clock forward by one hour during the summer months.

When DST is not active (tm_isdst = 0), it's like the clock is set to the regular time.
When DST is active (tm_isdst = 1), it's like the clock has been moved forward by an hour.
If you don't know if DST is active (tm_isdst = -1), it's like the clock doesn't have any hands, so you can't tell the time.

Code Example:

import time

# Get the current time
current_time = time.localtime()

# Check if DST is active
if current_time.tm_isdst == 0:
    print("DST is not active")
elif current_time.tm_isdst == 1:
    print("DST is active")
else:
    print("DST information is not available")

Real-World Applications:

Scheduling appointments: To ensure meetings and events are scheduled at the correct time zone, considering DST.
Managing time-sensitive operations: To adjust processes or systems based on DST changes, such as in financial markets or manufacturing.
Tracking user activity: To analyze data and usage patterns that may be influenced by DST, such as website traffic or app usage.

Attribute: tm_zone

Definition:

The tm_zone attribute represents the abbreviation of the timezone name.

Values:

The value can vary depending on the timezone you are in.
For example, in the Eastern Time Zone, the tm_zone value would be "EST".

Usage:

You can access the tm_zone attribute using the following code:

import time

# Get the current time
current_time = time.localtime()

# Access the tm_zone attribute
timezone_abbreviation = current_time.tm_zone

# Print the timezone abbreviation
print(timezone_abbreviation)

Output:

EST

Real-World Applications:

The tm_zone attribute is useful for:

Displaying the current timezone in your program.
Converting timestamps to and from different timezones.

struct_time

The struct_time object in Python's time module represents a specific point in time, and it is often used in conjunction with the time.mktime() and time.strptime() functions.

The struct_time object has the following attributes:

tm_year: The year (e.g., 2023)
tm_mon: The month (e.g., 9 for September)
tm_mday: The day of the month (e.g., 15)
tm_hour: The hour (e.g., 13 for 1 PM)
tm_min: The minute (e.g., 30)
tm_sec: The second (e.g., 45)
tm_wday: The day of the week (e.g., 0 for Monday)
tm_yday: The day of the year (e.g., 257 for September 15th)
tm_isdst: Whether or not daylight saving time is in effect (e.g., 1 for yes, 0 for no)

mktime()

The time.mktime() function takes a struct_time object as input and returns a float representing the number of seconds since the epoch (January 1, 1970 at midnight UTC).

For example:

import time

# Create a struct_time object representing September 15, 2023 at 1:30 PM
t = time.strptime("2023-09-15 13:30:00", "%Y-%m-%d %H:%M:%S")

# Convert the struct_time object to a float representing the number of seconds since the epoch
seconds = time.mktime(t)

print(seconds)

Output:

1663225400.0

strptime()

The time.strptime() function takes a string representing a date and time and a format string as input, and returns a struct_time object.

The format string specifies the format of the date and time string. The following table lists the most common format specifiers:

Format Specifier

Description

Year

Month

Day of the month

Hour (24-hour clock)

Minute

Second

For example:

import time

# Create a string representing September 15, 2023 at 1:30 PM
date_string = "2023-09-15 13:30:00"

# Create a format string
format_string = "%Y-%m-%d %H:%M:%S"

# Convert the date and time string to a struct_time object
t = time.strptime(date_string, format_string)

print(t)

Output:

time.struct_time(tm_year=2023, tm_mon=9, tm_mday=15, tm_hour=13, tm_min=30, tm_sec=0, tm_wday=4, tm_yday=258, tm_isdst=-1)

Potential Applications

The struct_time object, mktime(), and strptime() functions can be used in a variety of real-world applications, such as:

Parsing and formatting dates and times
Converting between different time zones
Calculating the difference between two dates or times

What is time() in Python?

Simplified Explanation:

time() is a function in Python that tells you how many seconds have passed since a specific date called the "epoch." The epoch is January 1, 1970 at 00:00:00 UTC.

Detailed Explanation:

time() returns a floating-point number representing the number of seconds since the epoch. Floating-point numbers have decimal points, so they can represent values like 123.456.

Precision:

Not all systems record time with the same precision. Some may only update their clocks once per second, so time() may return the same value for several seconds in a row.

Decreasing Values:

Normally, time() should always return increasing values. However, if the system clock is manually changed back, time() may return a lower value than before.

Converting to Other Time Formats:

You can convert the seconds since the epoch to other time formats using the gmtime or localtime functions. These functions take the seconds and return a struct_time object, which contains various date and time components like the year, month, and hour.

Example:

import time

# Get the current time in seconds since the epoch
seconds_since_epoch = time.time()

# Print the seconds
print("Seconds since the epoch:", seconds_since_epoch)

# Convert seconds to a struct_time object in UTC
utc_time = time.gmtime(seconds_since_epoch)

# Print the UTC time components
print("UTC time:", utc_time)

# Convert seconds to a struct_time object in local time
local_time = time.localtime(seconds_since_epoch)

# Print the local time components
print("Local time:", local_time)

Real-World Applications:

Timestamping: Adding timestamps to events to track when they occurred.
Time Measurement: Measuring how long it takes for certain tasks to complete.
Scheduling: Setting up tasks to run at specific times.
Date and Time Manipulation: Calculating dates and times based on user input or past events.
Logging: Recording events and their timestamps for analysis and debugging.

Function: time_ns()

Simplified Explanation:

This function returns the current time as an integer representing the number of nanoseconds (billionths of a second) that have passed since a fixed point in time known as the "epoch." This point is typically January 1, 1970 at 00:00:00 Coordinated Universal Time (UTC).

Usage:

To use this function, simply call it without any arguments:

current_time_ns = time_ns()

The result will be an integer representing the current time in nanoseconds.

Real-World Application:

This function is commonly used in situations where very precise timing is required, such as:

Measuring the execution time of code snippets
Synchronization between different processes or systems
Generating time-based unique identifiers

Example:

Here's a simple example that demonstrates the use of time_ns():

import time

# Record the start time
start_time_ns = time_ns()

# Perform some time-consuming tasks...

# Record the end time
end_time_ns = time_ns()

# Calculate the elapsed time in milliseconds
elapsed_time_ms = (end_time_ns - start_time_ns) / 1000000

print(f"Elapsed time: {elapsed_time_ms} milliseconds")

In this example, we record the start and end times of some time-consuming tasks in nanoseconds. Then, we calculate the elapsed time in milliseconds by subtracting the start time from the end time and dividing the result by 1 million (since there are 1 million nanoseconds in a millisecond).

Thread Time

Simplified Explanation: Imagine you have a thread (think of it as a worker in a factory) that is doing work. Thread time measures how long the thread has been working, not including any time it spent resting (sleeping). It's like a stopwatch that tracks the worker's active time, but not the time they take breaks.

Code Snippet:

import time

# Get the thread time
thread_time_seconds = time.thread_time()

Real-World Application: Thread time can be useful for performance monitoring. For example, you can use it to:

Track the performance of different threads in a multithreaded application.
Identify threads that are taking too long to execute.
Optimize your code to improve thread performance.

Time Complexity: The time complexity of thread_time() is O(1), meaning it takes a constant amount of time to get the thread time.

What is thread_time_ns Function?

The thread_time_ns function in Python's time module allows you to measure the time taken by a thread to execute in nanoseconds. This function is useful for profiling and optimizing your code to identify performance bottlenecks.

How to Use thread_time_ns Function:

To use the thread_time_ns function, simply call it without any arguments:

import time

# Measure the time taken by this block of code to execute
start_time = time.thread_time_ns()

# Your code here

# Measure the time taken by the previous code block
end_time = time.thread_time_ns()

# Calculate the time difference in nanoseconds
time_taken = end_time - start_time

# Print the time taken
print(f"Time taken: {time_taken} nanoseconds")

Real-World Example:

Here's an example of using the thread_time_ns function to profile a function that calculates the Fibonacci sequence:

import time

def fibonacci(n):
    if n < 2:
        return n
    return fibonacci(n - 1) + fibonacci(n - 2)

# Measure the time taken to calculate the 40th Fibonacci number
start_time = time.thread_time_ns()
result = fibonacci(40)
end_time = time.thread_time_ns()

# Calculate the time difference in milliseconds
time_taken = (end_time - start_time) / 1000000

# Print the time taken and the result
print(f"Time taken: {time_taken} milliseconds")
print(f"Fibonacci number: {result}")

Output:

Time taken: 122.926 milliseconds
Fibonacci number: 102334155

Potential Applications:

The thread_time_ns function has various applications in real-world scenarios, such as:

Profiling and optimizing code: Identify performance bottlenecks and optimize code to improve efficiency.
Measuring the performance of parallel code: Analyze the performance of multi-threaded code and identify potential issues.
Scheduling and resource allocation: Manage thread schedules and allocate resources based on performance measurements.

tzset() Function

Pretend you have a clock that keeps time based on the rules of your local area, like the timezone you live in. This function, called tzset(), lets you change the rules that your clock follows.

It works by checking an environment variable called TZ, which is like a secret code that tells your computer how to adjust the time. The format of this code looks something like this:

std offset [dst [offset [,start[/time], end[/time]]]]

std and dst: These are the names of the timezones you want to use. For example, "EST" for Eastern Standard Time and "EDT" for Eastern Daylight Time.
offset: This number tells you how many hours your timezone is ahead of or behind Coordinated Universal Time (UTC), which is the standard time around the world. If it starts with a minus sign (-), it means your timezone is behind UTC. Otherwise, it's ahead.
start and end: These tell your clock when to switch between standard and daylight saving time. The format is a bit complicated, but it basically uses numbers to represent days of the year or weeks of the month.

Clock ID Constants

These are special numbers that tell your computer what kind of clock you want to use. They can be used with other functions like clock_getres and clock_gettime.

CLOCK_BOOTTIME: This is like a regular clock, but it keeps track of time even when your computer is asleep.
CLOCK_HIGHRES: This is a special clock that tries to be as accurate as possible, even down to the nanosecond.
CLOCK_MONOTONIC: This clock always keeps increasing, even if you change the time on your computer.
CLOCK_MONOTONIC_RAW: Similar to the above, but it doesn't get affected by things like network time adjustments.
CLOCK_PROCESS_CPUTIME_ID: This clock tracks how much time your computer's processor has been working.
CLOCK_PROF: Similar to the above, but it only tracks CPU time for your current program.
CLOCK_TAI: This clock follows a very precise time standard called International Atomic Time.
CLOCK_THREAD_CPUTIME_ID: This clock tracks how much time a specific thread in your program has been running.
CLOCK_UPTIME: This clock keeps track of how long your computer has been running without being turned off.
CLOCK_UPTIME_RAW: Similar to the above, but it doesn't get affected by things like frequency adjustments.

Timezone Constants

These are values that tell you about the current timezone settings.

altzone: The difference in hours between the local daylight saving time and UTC.
daylight: A number that's not zero if your timezone uses daylight saving time.
timezone: The difference in hours between the local standard time and UTC.
tzname: A tuple with two strings - the first is the name of the local standard time, and the second is the name of the local daylight saving time.

Real-World Applications

tzset(): Useful for programs that need to work with multiple timezones or adjust for daylight saving time.
Clock ID Constants: Used for accurate timing operations, such as measuring the performance of code or synchronizing events.
Timezone Constants: Used to display the current time and date in the correct timezone or convert between timezones.

Example Code

import time

# Change the timezone to Eastern Time
time.tzset('EST+05EDT,M4.1.0,M10.5.0')

# Get the current time
now = time.time()

# Convert the current time to a string
current_time = time.strftime('%X %x %Z')

# Print the current time
print(current_time)

This code sets the timezone to Eastern Time, gets the current time as a number of seconds since January 1, 1970, and then converts it to a string in the format "HH:MM:SS MM/DD/YY DST". The output might look something like "02:07:36 05/08/03 EDT".

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