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time.perf_counter() function in Python

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  • Difficulty Level : Easy
  • Last Updated : 23 Mar, 2022
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The time module provides various time-related functions. We must import the time module before using perf_counter() so we can access the function without throwing any errors.
The perf_counter() function always returns the float value of time in seconds. Return the value (in fractional seconds) of a performance counter, i.e. a clock with the highest available resolution to measure a short duration. It does include time elapsed during sleep and is system-wide. The reference point of the returned value is undefined, so that only the difference between the results of consecutive calls is valid. In between this we can use time.sleep() and likewise functions.
Code #1: Understand the usage of the perf_counter
 

Python3




# Python program to show time by perf_counter()
from time import perf_counter
 
# integer input from user, 2 input in single line
n, m = map(int, input().split())
 
# Start the stopwatch / counter
t1_start = perf_counter()
 
for i in range(n):
    t = int(input()) # user gave input n times
    if t % m == 0:
        print(t)
 
# Stop the stopwatch / counter
t1_stop = perf_counter()
 
print("Elapsed time:", t1_stop, t1_start)
 
 
print("Elapsed time during the whole program in seconds:",
                                        t1_stop-t1_start)


Output: 
 

pref_counter_ns(): 
It always gives the integer value of time in nanoseconds. Similar to perf_counter(), but return time as nanoseconds.
Code #2: Usage of the perf_counter_ns and how to implement it. 
 

Python3




# Python program to show time by
# perf_counter_ns()
from time import perf_counter_ns
 
# integer input from user, 2 input in single line
n, m = map(int, input().split())
 
# Start the stopwatch / counter
t1_start = perf_counter_ns()
 
for i in range(n):
    t = int(input()) # user gave input n times
    if t % m == 0:
        print(t)
 
# Stop the stopwatch / counter
t1_stop = perf_counter_ns()
 
print("Elapsed time:", t1_stop, 'ns', t1_start, 'ns')
 
print("Elapsed time during the whole program in ns after n, m inputs:",
       t1_stop-t1_start, 'ns')


Output: 
 

Compare both the outputs of the program as perf_counter() returns in seconds and pers_counter_ns() returns in nanoseconds.
Advantages of perf_counter() : 
1. perf_counter() will give you more precise value than time.clock() function . 
2. From Python3.8 time.clock() function will be deleted and perf_counter will be used. 
3. We can calculate float and integer both values of time in seconds and nanoseconds. 
 


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