[FIXED] Running final function after stopping a loop seems to have a time difference in Python

Issue

I am writing a Python script that will show me running data when running on my treadmill because the display panel is broken. It's going to use GPIO pins on a Raspberry Pi, so whenever the belt on the treadmill goes around, it can have a metal piece that shorts pins (they act as a button). It calculates speed depending on how fast the belt went around.

This means time is very important here. I've set up a loop in rev_counter() that gets the time and then when the "button" is pressed, it records the time again. Just to test it while I'm writing this program, I've simulated a button press with sleep(). I set it to 1.27841272276 seconds because this would be the time the belt would go around for a 7:30-minute mile pace. I've been trying to get it as close to that pace as possible.

I have gotten it to work pretty well. It is right on or maybe one second off while showing the info in the middle of the workout. The problem is, when I end the workout with CTRL+C so it goes to the results, the average mile pace ends up being off. It should be 7:30-7:31, but it ends up being 7:34-7:36. I'm pretty sure the time gets offset between when I stop the rev_counter() loop and when it calculates the results in results(). For some reason, when I ran the update_display() function in rev_counter() with Thread, it seemed to help. Could stopping in the middle of this loop be causing a problem? Why does only results() and not both rev_counter() and results() not get the time issue?

Here is my Python script:

import math
import os
import time
# from gpiozero import Button
from threading import Thread
from time import sleep

# belt_button = Button(2)


def display(original_time=None, total_distance=None, current_speed=None, prev_rev_time=None):
    os.system('clear')
    print('Current Workout Information')
    print('')
    if original_time is None:
        print(f'Time elapsed: --:--:--')
        print('')
        print('Distance')
        print(f'Miles: --')
        print(f'Kilometers: --')
        print('')
        print('Current Speed')
        print(f'M/H: --')
        print(f'KM/H: --')
        print('')
        print('Pace')
        print(f'Mile: --')
        print(f'Kilometer: --')
    else:
        seconds_elapsed = prev_rev_time - original_time
        time_elapsed = increment(seconds_elapsed)
        mi = total_distance / 5280
        km = total_distance / 3280.84
        mph = current_speed / 1.46667
        kmph = current_speed * 1.09728
        min_mi = 60 / mph
        min_km = 60 / kmph
        mi_pace_min = math.floor(min_mi)
        mi_pace_sec = round((min_mi * 60) % 60)
        if mi_pace_sec < 10:
            mi_pace_sec = f'0{mi_pace_sec}'
        km_pace_min = math.floor(min_km)
        km_pace_sec = round((min_km * 60) % 60)
        if km_pace_sec < 10:
            km_pace_sec = f'0{km_pace_sec}'
        print(f'Time elapsed: {time_elapsed}')
        print('')
        print('Distance')
        print(f'Miles: {round(mi, 2)}')
        print(f'Kilometers: {round(km, 2)}')
        print('')
        print('Current Speed')
        print(f'M/H: {round(mph, 2)}')
        print(f'KM/H: {round(kmph, 2)}')
        print('')
        print('Pace')
        if current_speed == 0:
            print(f'Mile: 0')
            print(f'Kilometer: 0')
        else:
            print(f'Mile: {mi_pace_min}:{mi_pace_sec}')
            print(f'Kilometer: {km_pace_min}:{km_pace_sec}')


def increment(seconds_elapsed):
    seconds_elapsed = math.floor(seconds_elapsed)
    h = seconds_elapsed // 3600
    m = (seconds_elapsed // 60) % 60
    s = seconds_elapsed % 60
    if h < 10:
        h = f'0{h}'
    if m < 10:
        m = f'0{m}'
    if s < 10:
        s = f'0{s}'
    return f'{h}:{m}:{s}'


def rev_counter():
    revolutions = 0
    prev_rev_time = 0
    original_time = time.time()
    try:
        while True:
            prev_rev_time = time.time()
            # GPIO stuff
            # sleep(0.25)
            # belt_button.wait_for_press()
            sleep(1.27841272276)
            rev_time = time.time()
            revolutions += 1
            update_display(original_time, prev_rev_time, rev_time, revolutions)
            # Alternate code
            # thread = Thread(target=update_display, args=(original_time, prev_rev_time, rev_time, revolutions))
            # thread.start()
    except KeyboardInterrupt:
        os.system('clear')
        total_distance = 15 * revolutions
        results(original_time, prev_rev_time, total_distance)


def update_display(original_time, prev_rev_time, rev_time, revolutions):
    # feet * rev count
    # 15 = Length of my treadmill in feet
    total_distance = 15 * revolutions
    # feet / second
    rev_seconds = rev_time - prev_rev_time
    current_speed = 15 / rev_seconds
    display(original_time, total_distance, current_speed, prev_rev_time)


def results(original_time, prev_rev_time, total_distance):
    try:
        os.system('clear')
        seconds_elapsed = prev_rev_time - original_time
        time_elapsed = increment(seconds_elapsed)
        print('Workout Results')
        print('')
        if total_distance == 0:
            print(f'Total time: {time_elapsed}')
            print('')
            print('Distance')
            print(f'Miles: 0')
            print(f'Kilometers: 0')
            print('')
            print('Average Speed')
            print(f'M/H: 0')
            print(f'KM/H: 0')
            print('')
            print('Average Pace')
            print(f'Mile: 00:00')
            print(f'Kilometer: 00:00')
        else:
            average_speed = total_distance / seconds_elapsed
            mi = total_distance / 5280
            km = total_distance / 3280.84
            mph = average_speed / 1.46667
            kmph = average_speed * 1.09728
            min_mi = 60 / mph
            min_km = 60 / kmph
            mi_pace_min = math.floor(min_mi)
            mi_pace_sec = round((min_mi * 60) % 60)
            if mi_pace_sec < 10:
                mi_pace_sec = f'0{mi_pace_sec}'
            km_pace_min = math.floor(min_km)
            km_pace_sec = round((min_km * 60) % 60)
            if km_pace_sec < 10:
                km_pace_sec = f'0{km_pace_sec}'
            print(f'Total time: {time_elapsed}')
            print('')
            print('Distance')
            print(f'Miles: {round(mi, 2)}')
            print(f'Kilometers: {round(km, 2)}')
            print('')
            print('Average Speed')
            print(f'M/H: {round(mph, 2)}')
            print(f'KM/H: {round(kmph, 2)}')
            print('')
            print('Average Pace')
            print(f'Mile: {mi_pace_min}:{mi_pace_sec}')
            print(f'Kilometer: {km_pace_min}:{km_pace_sec}')
        print('')
        input('Exit ')
        os.system('clear')
    except KeyboardInterrupt:
        os.system('clear')


def main():
    os.system('clear')
    while True:
        try:
            print('AC Treadmill Workout Program')
            print('')
            input('Start Workout ')
            display()
            rev_counter()
        except KeyboardInterrupt:
            print('\n')
            print('Quitting... ')
            break


if __name__ == '__main__':
    main()

To run this program without any issues, run it in a Unix environment or Windows if you change all the os.system('clear') lines to os.system('cls'). Also make sure to run it in the terminal because my IDE (PyCharm) doesn't allow it to clear even when I set the TERM environment variable.

Solution

I ended up just using Thread and it got it to work the best it will probably work. Later, I'm going to convert the program to C++ so it has better performance and have a GUI and all sorts of stuff.

Here is what it ended up looking like:

import math
import os
import time
from gpiozero import Button
from threading import Thread
from time import sleep

belt_button = Button(2)

# 15 is the length of my belt in feet
belt_length = 15


def display(original_time=None, total_distance=None, current_speed=None, prev_rev_time=None):
    os.system('clear')
    print('Current Workout Information')
    print('')
    if original_time is None:
        print(f'Time elapsed: --:--:--')
        print('')
        print('Distance')
        print(f'Miles: --')
        print(f'Kilometers: --')
        print('')
        print('Current Speed')
        print(f'M/H: --')
        print(f'KM/H: --')
        print('')
        print('Pace')
        print(f'Mile: --')
        print(f'Kilometer: --')
    else:
        seconds_elapsed = prev_rev_time - original_time
        time_elapsed = increment(seconds_elapsed)
        mi = total_distance / 5280
        km = total_distance / 3280.84
        mph = current_speed / 1.46667
        kmph = current_speed * 1.09728
        min_mi = 60 / mph
        min_km = 60 / kmph
        mi_pace_min = math.floor(min_mi)
        mi_pace_sec = round((min_mi * 60) % 60)
        if mi_pace_sec < 10:
            mi_pace_sec = f'0{mi_pace_sec}'
        km_pace_min = math.floor(min_km)
        km_pace_sec = round((min_km * 60) % 60)
        if km_pace_sec < 10:
            km_pace_sec = f'0{km_pace_sec}'
        print(f'Time elapsed: {time_elapsed}')
        print('')
        print('Distance')
        print(f'Miles: {round(mi, 2)}')
        print(f'Kilometers: {round(km, 2)}')
        print('')
        print('Current Speed')
        print(f'M/H: {round(mph, 2)}')
        print(f'KM/H: {round(kmph, 2)}')
        print('')
        print('Pace')
        if current_speed == 0:
            print(f'Mile: 0')
            print(f'Kilometer: 0')
        else:
            print(f'Mile: {mi_pace_min}:{mi_pace_sec}')
            print(f'Kilometer: {km_pace_min}:{km_pace_sec}')


def increment(seconds_elapsed):
    seconds_elapsed = math.floor(seconds_elapsed)
    h = seconds_elapsed // 3600
    m = (seconds_elapsed // 60) % 60
    s = seconds_elapsed % 60
    if h < 10:
        h = f'0{h}'
    if m < 10:
        m = f'0{m}'
    if s < 10:
        s = f'0{s}'
    return f'{h}:{m}:{s}'


def rev_counter():
    revolutions = 0
    prev_rev_time = 0
    original_time = time.time()
    try:
        while True:
            prev_rev_time = time.time()
            sleep(0.25)
            belt_button.wait_for_press()
            rev_time = time.time()
            revolutions += 1
            thread = Thread(target=update_display, args=(original_time, prev_rev_time, rev_time, revolutions))
            thread.start()
    except KeyboardInterrupt:
        os.system('clear')
        total_distance = belt_length * revolutions
        results(original_time, prev_rev_time, total_distance)


def update_display(original_time, prev_rev_time, rev_time, revolutions):
    # feet * rev count
    # 15 = Length of my treadmill in feet
    total_distance = belt_length * revolutions
    rev_seconds = rev_time - prev_rev_time
    # feet / second
    current_speed = belt_length / rev_seconds
    display(original_time, total_distance, current_speed, prev_rev_time)


def results(original_time, prev_rev_time, total_distance):
    try:
        os.system('clear')
        seconds_elapsed = prev_rev_time - original_time
        time_elapsed = increment(seconds_elapsed)
        print('Workout Results')
        print('')
        if total_distance == 0:
            print(f'Total time: {time_elapsed}')
            print('')
            print('Distance')
            print(f'Miles: 0')
            print(f'Kilometers: 0')
            print('')
            print('Average Speed')
            print(f'M/H: 0')
            print(f'KM/H: 0')
            print('')
            print('Average Pace')
            print(f'Mile: 00:00')
            print(f'Kilometer: 00:00')
        else:
            average_speed = total_distance / seconds_elapsed
            mi = total_distance / 5280
            km = total_distance / 3280.84
            mph = average_speed / 1.46667
            kmph = average_speed * 1.09728
            min_mi = 60 / mph
            min_km = 60 / kmph
            mi_pace_min = math.floor(min_mi)
            mi_pace_sec = round((min_mi * 60) % 60)
            if mi_pace_sec < 10:
                mi_pace_sec = f'0{mi_pace_sec}'
            km_pace_min = math.floor(min_km)
            km_pace_sec = round((min_km * 60) % 60)
            if km_pace_sec < 10:
                km_pace_sec = f'0{km_pace_sec}'
            print(f'Total time: {time_elapsed}')
            print('')
            print('Distance')
            print(f'Miles: {round(mi, 2)}')
            print(f'Kilometers: {round(km, 2)}')
            print('')
            print('Average Speed')
            print(f'M/H: {round(mph, 2)}')
            print(f'KM/H: {round(kmph, 2)}')
            print('')
            print('Average Pace')
            print(f'Mile: {mi_pace_min}:{mi_pace_sec}')
            print(f'Kilometer: {km_pace_min}:{km_pace_sec}')
        print('')
        input('Exit ')
        os.system('clear')
    except KeyboardInterrupt:
        os.system('clear')


def main():
    os.system('clear')
    while True:
        try:
            print('ASHER Treadmill Workout Program')
            print('')
            input('Start Workout ')
            display()
            rev_counter()
        except KeyboardInterrupt:
            print('\n')
            print('Quitting... ')
            break


if __name__ == '__main__':
    main()

Answered By - ThrownRedstone