timeit.py

import timeit as _timeit, math, sys

def _format_time(timespan, precision=3):
    if timespan >= 60.0:
        parts = [('d', 60*60*24),('h', 60*60),('min', 60), ('s', 1)]
        time = []
        leftover = timespan
        for suffix, length in parts:
            value = int(leftover / length)
            if value > 0:
                leftover = leftover % length
                time.append(f'{value}{suffix}')
            if leftover < 1:
                break
        return ' '.join(time)

    units = ['s', 'ms', 'us', 'ns']
    scaling = [1, 1e3, 1e6, 1e9]

    if timespan > 0.0:
        order = min(-int(math.floor(math.log10(timespan)) // 3), 3)
    else:
        order = 3
    return f"{timespan * scaling[order]:.{precision-1}f} {units[order]}"

def timeit(stmt, setup='pass', repeat=7, number=0, precision=3):
    timer = _timeit.Timer(stmt, setup)

    if number == 0:
        for index in range(0, 10):
            number = 10 ** index
            time_number = timer.timeit(number)
            if time_number >= 0.2:
                break

    all_runs = timer.repeat(repeat, number)
    best = min(all_runs) / number
    worst = max(all_runs) / number

    if worst > 4 * best and best > 0 and worst > 1e-6:
        print(f"The slowest run took {worst/best:0.2f} times longer than the "
              "fastest. This could mean that an intermediate result "
              "is being cached.")

    fmt = "{mean} {pm} {std} per loop (mean {pm} std. dev. of {runs} run{run_plural}, {number} loop{loop_plural} each)"
    timings = [ dt / number for dt in all_runs]
    average = lambda: math.fsum(timings) / len(timings)
    stdev = lambda: (math.fsum([(x - average()) ** 2 for x in timings]) / len(timings)) ** 0.5
    pm = '+-'
    if getattr(sys.stdout, 'encoding', None):
        try:
            '\xb1'.encode(sys.stdout.encoding)
            pm = '\xb1'
        except:
            pass

    print(fmt.format(pm = pm, runs = repeat, number = number,
        loop_plural = "" if number == 1 else "s",
        run_plural = "" if repeat == 1 else "s",
        mean = _format_time(average(), precision),
        std = _format_time(stdev(), precision)))