Python Program to Create a Lap Timer

In this article, we will make a simple timer to calculate lap-time intervals using Python.

time:  This module provides various time-related functions. It is a part of Python's standard library and does not require installation.

Approach:

The user needs to press ENTER to complete each lap. The timer keeps counting till CTRL+C is pressed. For each lap we calculate the lap time by subtracting the current time from the total time at the end of the previous lap. The time() function of the time module, returns the current epoch time in milliseconds. 

Below is the implementation:

# importing libraries
import time


# Timer starts
starttime = time.time()
lasttime = starttime
lapnum = 1

print("Press ENTER to count laps.\nPress CTRL+C to stop")

try:
    while True:

        # Input for the ENTER key press
        input()

        # The current lap-time
        laptime = round((time.time() - lasttime), 2)

        # Total time elapsed
        # since the timer started
        totaltime = round((time.time() - starttime), 2)

        # Printing the lap number,
        # lap-time and total time
        print("Lap No. "+str(lapnum))
        print("Total Time: "+str(totaltime))
        print("Lap Time: "+str(laptime))

        print("*"*20)

        # Updating the previous total time
        # and lap number
        lasttime = time.time()
        lapnum += 1

# Stopping when CTRL+C is pressed
except KeyboardInterrupt:
    print("Done")

Output:

ENTER to count laps.
Press CTRL+C to stop
Lap No. 1
Total Time: 1.09
Lap Time: 1.09
********************
Lap No. 2
Total Time: 2.66
Lap Time: 1.41
********************
Lap No. 3
Total Time: 5.06
Lap Time: 2.23
********************
Lap No. 4
Total Time: 5.63
Lap Time: 0.4
********************
Done

Time complexity: O(1) - the program runs in constant time, regardless of the size of the input.

Auxiliary space: O(1) - the program uses a fixed amount of memory, regardless of the size of the input