How to overwrite the previous print to stdout?

Question

If I had the following code:

for x in range(10):
     print(x)

I would get the output of

1
2
etc..

What I would like to do is instead of printing a newline, I want to replace the previous value and overwrite it with the new value on the same line.

Answer 1

Simple Version

One way is to use the carriage return ('\r') character to return to the start of the line without advancing to the next line.

Python 3

for x in range(10):
    print(x, end='\r')
print()

Python 2.7 forward compatible

from __future__ import print_function
for x in range(10):
    print(x, end='\r')
print()

Python 2.7

for x in range(10):
    print '{}\r'.format(x),
print

Python 2.0-2.6

for x in range(10):
    print '{0}\r'.format(x),
print

In the latter two (Python 2-only) cases, the comma at the end of the print statement tells it not to go to the next line. The last print statement advances to the next line so your prompt won't overwrite your final output.

Line Cleaning

If you can’t guarantee that the new line of text is not shorter than the existing line, then you just need to add a “clear to end of line” escape sequence, '\x1b[1K' ('\x1b' = ESC):

for x in range(75):
    print('*' * (75 - x), x, end='\x1b[1K\r')
print()

Answer 2

Since I ended up here via Google but am using Python 3, here's how this would work in Python 3:

for x in range(10):
    print("Progress {:2.1%}".format(x / 10), end="\r")

Related answer here: How can I suppress the newline after a print statement?

Answer 3

@Mike DeSimone answer will probably work most of the time. But...

for x in ['abc', 1]:
    print '{}\r'.format(x),

-> 1bc

This is because the '\r' only goes back to the beginning of the line but doesn't clear the output.

If POSIX support is enough for you, the following would clear the current line and leave the cursor at its beginning:

print '\x1b[2K\r',

It uses ANSI escape code to clear the terminal line. More info can be found in wikipedia and in this great talk.

Other approach

This other, (arguably worse) solution I have found looks like this:

last_x = ''
for x in ['abc', 1]:
    print ' ' * len(str(last_x)) + '\r',
    print '{}\r'.format(x),
    last_x = x

-> 1

One advantage is that it will work on windows too.

Answer 4

I had the same question before visiting this thread. For me the sys.stdout.write worked only if I properly flush the buffer i.e.

for x in range(10):
    sys.stdout.write('\r'+str(x))
    sys.stdout.flush()

Without flushing, the result is printed only at the end out the script

Answer 5

Suppress the newline and print \r.

print 1,
print '\r2'

or write to stdout:

sys.stdout.write('1')
sys.stdout.write('\r2')

Answer 6

for x in range(10):
    time.sleep(0.5) # shows how its working
    print("\r {}".format(x), end="")

time.sleep(0.5) is to show how previous output is erased and new output is printed "\r" when its at the start of print message , it gonna erase previous output before new output.

Answer 7

Here's a cleaner, more "plug-and-play", version of @Nagasaki45's answer. Unlike many other answers here, it works properly with strings of different lengths. It achieves this by clearing the line with just as many spaces as the length of the last line printed print. Will also work on Windows.

def print_statusline(msg: str):
    last_msg_length = len(getattr(print_statusline, 'last_msg', ''))
    print(' ' * last_msg_length, end='\r')
    print(msg, end='\r')
    sys.stdout.flush()  # Some say they needed this, I didn't.
    setattr(print_statusline, 'last_msg', msg)

Usage

Simply use it like this:

for msg in ["Initializing...", "Initialization successful!"]:
    print_statusline(msg)
    time.sleep(1)

This small test shows that lines get cleared properly, even for different lengths:

for i in range(9, 0, -1):
    print_statusline("{}".format(i) * i)
    time.sleep(0.5)

Answer 8

Try this:

import time
while True:
    print("Hi ", end="\r")
    time.sleep(1)
    print("Bob", end="\r")
    time.sleep(1)

It worked for me. The end="\r" part is making it overwrite the previous line.

WARNING!

If you print out hi, then print out hello using \r, you’ll get hillo because the output wrote over the previous two letters. If you print out hi with spaces (which don’t show up here), then it will output hi. To fix this, print out spaces using \r.

Answer 9

This works on Windows and python 3.6

import time
for x in range(10):
    time.sleep(0.5)
    print(str(x)+'\r',end='')

Answer 10

I couldn't get any of the solutions on this page to work for IPython, but a slight variation on @Mike-Desimone's solution did the job: instead of terminating the line with the carriage return, start the line with the carriage return:

for x in range(10):
    print '\r{0}'.format(x),

Additionally, this approach doesn't require the second print statement.

Answer 11

The accepted answer is not perfect. The line that was printed first will stay there and if your second print does not cover the entire new line, you will end up with garbage text.

To illustrate the problem save this code as a script and run it (or just take a look):

import time

n = 100
for i in range(100):
    for j in range(100):
        print("Progress {:2.1%}".format(j / 100), end="\r")
        time.sleep(0.01)
    print("Progress {:2.1%}".format(i / 100))

The output will look something like this:

Progress 0.0%%
Progress 1.0%%
Progress 2.0%%
Progress 3.0%%

What works for me is to clear the line before leaving a permanent print. Feel free to adjust to your specific problem:

import time

ERASE_LINE = '\x1b[2K' # erase line command
n = 100
for i in range(100):
    for j in range(100):
        print("Progress {:2.1%}".format(j / 100), end="\r")
        time.sleep(0.01)
    print(ERASE_LINE + "Progress {:2.1%}".format(i / 100)) # clear the line first

And now it prints as expected:

Progress 0.0%
Progress 1.0%
Progress 2.0%
Progress 3.0%

Answer 12

I'm a bit surprised nobody is using the backspace character. Here's one that uses it.

import sys
import time

secs = 1000

while True:
    time.sleep(1)  #wait for a full second to pass before assigning a second
    secs += 1  #acknowledge a second has passed

    sys.stdout.write(str(secs))

    for i in range(len(str(secs))):
        sys.stdout.write('\b')

Answer 13

Here's my solution! Windows 10, Python 3.7.1

I'm not sure why this code works, but it completely erases the original line. I compiled it from the previous answers. The other answers would just return the line to the beginning, but if you had a shorter line afterwards, it would look messed up like hello turns into byelo.

import sys
#include ctypes if you're on Windows
import ctypes
kernel32 = ctypes.windll.kernel32
kernel32.SetConsoleMode(kernel32.GetStdHandle(-11), 7)
#end ctypes

def clearline(msg):
    CURSOR_UP_ONE = '\033[K'
    ERASE_LINE = '\x1b[2K'
    sys.stdout.write(CURSOR_UP_ONE)
    sys.stdout.write(ERASE_LINE+'\r')
    print(msg, end='\r')

#example
ig_usernames = ['beyonce','selenagomez']
for name in ig_usernames:
    clearline("SCRAPING COMPLETE: "+ name)

Output - Each line will be rewritten without any old text showing:

SCRAPING COMPLETE: selenagomez

Next line (rewritten completely on same line):

SCRAPING COMPLETE: beyonce

Answer 14

(Python3) This is what worked for me. If you just use the \010 then it will leave characters, so I tweaked it a bit to make sure it's overwriting what was there. This also allows you to have something before the first print item and only removed the length of the item.

print("Here are some strings: ", end="")
items = ["abcd", "abcdef", "defqrs", "lmnop", "xyz"]
for item in items:
    print(item, end="")
    for i in range(len(item)): # only moving back the length of the item
        print("\010 \010", end="") # the trick!
        time.sleep(0.2) # so you can see what it's doing

Answer 15

One more answer based on the prevous answers.

Content of pbar.py: import sys, shutil, datetime

last_line_is_progress_bar=False


def print2(print_string):
    global last_line_is_progress_bar
    if last_line_is_progress_bar:
        _delete_last_line()
        last_line_is_progress_bar=False
    print(print_string)


def _delete_last_line():
    sys.stdout.write('\b\b\r')
    sys.stdout.write(' '*shutil.get_terminal_size((80, 20)).columns)
    sys.stdout.write('\b\r')
    sys.stdout.flush()


def update_progress_bar(current, total):
    global last_line_is_progress_bar
    last_line_is_progress_bar=True

    completed_percentage = round(current / (total / 100))
    current_time=datetime.datetime.now().strftime('%m/%d/%Y-%H:%M:%S')
    overhead_length = len(current_time+str(current))+13
    console_width = shutil.get_terminal_size((80, 20)).columns - overhead_length
    completed_width = round(console_width * completed_percentage / 100)
    not_completed_width = console_width - completed_width
    sys.stdout.write('\b\b\r')

    sys.stdout.write('{}> [{}{}] {} - {}% '.format(current_time, '#'*completed_width, '-'*not_completed_width, current,
                                        completed_percentage),)
    sys.stdout.flush()

Usage of script:

import time
from pbar import update_progress_bar, print2


update_progress_bar(45,200)
time.sleep(1)

update_progress_bar(70,200)
time.sleep(1)

update_progress_bar(100,200)
time.sleep(1)


update_progress_bar(130,200)
time.sleep(1)

print2('some text that will re-place current progress bar')
time.sleep(1)

update_progress_bar(111,200)
time.sleep(1)

print('\n') # without \n next line will be attached to the end of the progress bar
print('built in print function that will push progress bar one line up')
time.sleep(1)

update_progress_bar(111,200)
time.sleep(1)

Answer 16

Better to overwrite the whole line otherwise the new line will mix with the old ones if the new line is shorter.

import time, os
for s in ['overwrite!', 'the!', 'whole!', 'line!']:
    print(s.ljust(os.get_terminal_size().columns - 1), end="\r")
    time.sleep(1)

Had to use columns - 1 on Windows.

Answer 17

This worked for me, using Python 3.7.9 within Spyder, in Windows:

from IPython.display import clear_output
from time import sleep

def print_and_overwrite(text):
    '''Remember to add print() after the last print that you want to overwrite.'''
    clear_output(wait=True)
    print(text, end='\r')

for i in range(15):
    #I print the results backwards (from 15 to 1), to test shorter strings
    message = "Iteration %d out of 15" %(15-i)
    print_and_overwrite(message)
    sleep(0.5)

print() #This stops the overwriting
print("This will be on a new line")

Answer 18

Anyway if somebody wants to overprint (clear) a many lines previously printed in stdout, than this answer should be helpful for him. (Thanks Thijmen Dam for the nice article Overwrite Previously Printed Lines)

In ANSI console you can use special sequences:

\033[1A and \033[K

First of them lift up a cursor, second - erase a line entirely.

Example of the clearing a console (Python 3):

LINE_UP = '\033[1A'
LINE_CLEAR = '\033[K'
CONSOLE_HEIGHT = 24 #lines

def clear_console():
    for a in range(CONSOLE_HEIGHT):
        print(LINE_UP, end=LINE_CLEAR, flush=True)

or eventually simply (will clear screen and move cursor to 0,0):

print('\033[2J', end='', flush=True)

If you want just positioning cursor, then use this:

print('\033[<L>;<C>f', end='', flush=True)

where <L> and <C> are Line and Column correspondingly.

Handful reference for you ANSI escape sequences

Answer 19

Based off the responses I seen in this thread I made a nice little class that should be good across all platforms.

import sys
    
class PrintSameLine:
    """Class to correctly print on same line.
    """
    def __init__(self):
        self.last_message = ""

    def print_msg(self, msg: str):
        print(" " * len(self.last_message), end="\r", flush=True)
        print(msg, end="\r", flush=True)
        self.last_message = msg


# Note printing in reverse so you can see how it works
prnt = PrintSameLine()

for i in reverse(range(10)):
    prnt.print_msg(str(i))