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How to use Python timeit Module to measure elapsed time in Python In Python

Using Python time Module to measure elapsed time in Python

Python timeit module is often used to measure the execution time of small code snippets. We can also use the timeit() function, which executes an anonymous function with a number of executions. It temporarily turns off garbage collection while calculating the time of execution.

Example 1: Analyze how to use the timeit module

In this example, we will analyze how to use the timeit module and use it to find the execution time of a lambda expression. The code starts with importing the timeit module, and then we use the timeit() function from the module to find the execution time of the function.

Python3




# importing the module
import timeit
 
# define the code statement to test and
# calculate the execution time
exec_time = timeit.timeit("print('Hello World!')")
 
# printing the execution time in seconds
print(exec_time, "secs.")
 






                        









													
													
												

												
												

													
													
Output:

													
													
												

												
												

													
													
Hello World!
Hello World!
Hello World!
Hello World!
Hello World!
...
1.632629341998836 secs.

													
													
												

												
												

													
													
Explanation: The above code segment, will print “Hello World” 1000000 times (since default value of number parameter is 1000000). At the end, the code will print the execution time of the given code segment, measured in seconds.

													
													
												

												
												

													
													
Example 2: Using timeit.timeit() with predefined parameters

													
													
												

												
												

													
													
In this example, we’ll write a Python code segment having a function, and it’s call as a string and pass it to timeit.timeit() function. We’ll use a predefined number of iterations to count the execution time.

													
													
												

												
												

													
													




Python3















                                    




                                    

                                    




                                    




                                    

                                    

                                    
                                




















# importing the module


import timeit


 


 


# code segment to measure


code_segment = '''\


import random


def execute(n):


    return n**n


execute(random.randint(20, 50))


'''


 


# execute code segment and find the execution time


exec_time = timeit.timeit(code_segment, number=10**6)


 


# printing the execution time in secs.


# nearest to 3-decimal places


print(f"{exec_time:.03f} secs.")



















                        







                        









													
													
												

												
												

													
													
Output:

													
													
												

												
												

													
													
1.118 secs.

													
													
												

												
												

													
													
Explanations: In this example, we have defined a Python function and call to the function, everything written as a string representation. We test the running time of the code for 10**6 times and print out the time taken to execute the given function in seconds.

													
													
												

												
												

													
													
Example 3: How to measure elapsed time using timeit.repeat

													
													
												

												
												

													
													
We use the timeit.repeat() method instead of timeit.timeit() which takes a repeat parameter and saves you the trouble of creating a loop and storing the values in the array. This helps in getting an average elapsed time value from multiple execution of the same code segment.

													
													
												

												
												

													
													




Python3















                                    




                                    

                                    




                                    




                                    

                                    

                                    
                                




















# importing the module


import timeit


 


 


# function to test the execution time


def print_square(x):


    return x ** 2


 


 


t_records = timeit.repeat(lambda: print_square(3), number=10, repeat=5)


 


# printing the execution time


for index, exec_time in enumerate(t_records, 1):


    # printing execution time of code in microseconds


    m_secs = round(exec_time * 10 ** 6, 2)


    print(f"Case {index}: Time Taken: {m_secs}µs")



















                        







                        









													
													
												

												
												

													
													
Output:

													
													
												

												
												

													
													
Case 1: Time Taken: 4.41µs
Case 2: Time Taken: 3.15µs
Case 3: Time Taken: 3.07µs
Case 4: Time Taken: 3.04µs
Case 5: Time Taken: 3.08µs

													
													
												

												
												

													
													
Example 4: How to measure elapsed time using timeit.default_timer()

													
													
												

												
												

													
													
timeit.default_timer() uses the timeit.perf_counter() to record the timestamp of an instance in nanoseconds, and we can subtract end time from start time to get the execution time duration in nanoseconds.

													
													
												

												
												

													
													




Python3















                                    




                                    

                                    




                                    




                                    

                                    

                                    
                                




















# importing the module


import timeit


 


 


# define function


def print_square(x):


    return x ** 2


 


 


# record start time


t_0 = timeit.default_timer()


# call function


res = print_square(11111111)


# record end time


t_1 = timeit.default_timer()


 


# calculate elapsed time and print


elapsed_time = round((t_1 - t_0) * 10 ** 6, 3)


print(f"Elapsed time: {elapsed_time} µs")



















                        







                        









													
													
												

												
												

													
													
Output:

													
													
												

												
												

													
													
Elapsed time: 1.266 µs

													
													
												

												
											

											
											

												
How to measure elapsed time in Python?

												
												

													
													
In Python, we can measure the elapsed time on executing a code segment or a Python script using some built-in Python modules. Here we will cover the usage of time, timeit and datetime module.

													
													
												

												
											

										


										
										

											
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												Using Python time Module to measure elapsed time in Python