Multiline output in while loop

Question

My task is to write a function planning a track run. I have to add a while loop to see if the input parameter a_distance was covered and count the number of laps within this distance. I have the following (yet uncompleted) function defined:

import math  # ceil

LAP_DISTANCE = 400

def plan_track_run(a_distance):
    count = 0
    total = 0
    r_output = ""

    while total < a_distance:
        count = count + (1/(LAP_DISTANCE)*a_distance)
        total = total + count * LAP_DISTANCE
        r_output += f"lap #{math.ceil(count)} time ____ s in {count:.2f} x {LAP_DISTANCE}m ={total:.2f}m\n"

The output is a template to write down times for particular distances. The output when the a_distance is smaller than a lap distance (400 meters) can be seen here:

lap #1 time ____ s in 0.50 x 400m = 200.00m

Unfortunately, I do not achieve the desired output in the case when the a_distance is larger than a lap distance, e.g. 1500 meters. There should be a multiline output for each laps, counting upwards until the total number of laps and the total distance is displayed in the last line:

lap #1 time ____ s in 1.00 x 400m = 400.00m
lap #2 time ____ s in 2.00 x 400m = 800.00m
lap #3 time ____ s in 3.00 x 400m = 1200.00m
lap #4 time ____ s in 3.75 x 400m = 1500.00m

My current and wrong output for a_distance = 1500 is:

lap #4 time ____ s in 3.75 x 400m = 1500.00m

Please help me modify this code so that I achieve the desired output also for distances larger than 400 meters. Thank you in advance.

Answer 1

LAP_DISTANCE = 400
a_distance = 1500
count = count + (1/(LAP_DISTANCE)*a_distance) # 0 + 1/400*1500 = 3.75
total = total + count * LAP_DISTANCE # 0 + 3.75 * 400 = 1500

Your second formula fully cancels out the first one, leaving you with total == a_distance which will terminate the loop.

Why do you need to calculate the count from the distance? Just count = count + 1 should be enough, no? And honestly, I would rename that to lap to give it proper context.

The next total would be total = total + LAP_DISTANCE or total = count * LAP_DISTANCE. You should either build the cumulative sum or multiply to get the total, but not both at the same time. To avoid overshooting the distance, a simple conditional or math.min can be used.

Alternatively, compute the number of laps first (laps = math.ceil(a_distance/LAP_DISTANCE)) and then execute the loop laps times: for lap in range(laps): ...