Replace console output in Python

An easy solution is just writing "\r" before the string and not adding a newline; if the string never gets shorter this is sufficient...

sys.stdout.write("\rDoing thing %i" % i)
sys.stdout.flush()

Slightly more sophisticated is a progress bar... this is something I am using:

def start_progress(title):
    global progress_x
    sys.stdout.write(title + ": [" + "-"*40 + "]" + chr(8)*41)
    sys.stdout.flush()
    progress_x = 0

def progress(x):
    global progress_x
    x = int(x * 40 // 100)
    sys.stdout.write("#" * (x - progress_x))
    sys.stdout.flush()
    progress_x = x

def end_progress():
    sys.stdout.write("#" * (40 - progress_x) + "]\n")
    sys.stdout.flush()

You call start_progress passing the description of the operation, then progress(x) where x is the percentage and finally end_progress()

A more elegant solution could be:

def progress_bar(current, total, bar_length=20):
    fraction = current / total

    arrow = int(fraction * bar_length - 1) * '-' + '>'
    padding = int(bar_length - len(arrow)) * ' '

    ending = '\n' if current == total else '\r'

    print(f'Progress: [{arrow}{padding}] {int(fraction*100)}%', end=ending)

Call this function with current and total:

progress_bar(69, 100)

The result should be

Progress: [------------->      ] 69%

Note:

• For Python 3.6 and below
• For Python 2.x.

In python 3 you can do this to print on the same line:

print('', end='\r')

Especially useful to keep track of the latest update and progress.

I would also recommend tqdm from here if one wants to see the progress of a loop. It prints the current iteration and total iterations as a progression bar with an expected time of finishing. Super useful and quick. Works for python2 and python3.

It can be done without using the sys library if we look at the print() function

print(*objects, sep=' ', end='\n', file=sys.stdout, flush=False)

Here is my code:

def update(n):
    for i in range(n):
        print("i:",i,sep='',end="\r",flush=True)
        time.sleep(1)