How can I overwrite a print output with another specific print output? For example:
print("Overwrite this line", end="\r")
print("I do not want to overwrite any line")
print("I want to overwrite the first line")
How can I overwrite the first print statement with the third print statement?
I want to replace the first line, with the third line. The second line should remain as it is.
In this code example, the first line would be overwritten by the second one, but the I do not want that. I want the first line would be overwritten by the third one
You can use ANSI escape sequences, as long as your terminal supports them (this is the case on Linux, I'm not sure about Windows)
In particular, the interesting ones for this problem are:
\033[<N>A - Move the cursor up N lines
\033[<N>B - Move the cursor down N lines
You can print the first two lines normally, then for the third one move up 2 lines, print it (this will print a newline and move the cursor to the second line), move down 1 line and continue with your code. I interted some delays in the code so that the effect is visible:
print("Overwrite this line")
time.sleep(1)
print("I do not want to overwrite any line")
time.sleep(1)
print("\033[2AI want to overwrite the first line\033[1B")
You must use conditional statements. If statement for example:
choice = input('what do you want to display? 1 or 2')
if choice == '1' then:
print('I want to overwrite the first line')
else:
print('I do not want to overwrite any line')
Does this answer your question? If not, please elaborate.
Use escape sequence \r for this purpose. And for wait use time.sleep
import time
print("Overwrite this line", end="")
time.sleep(10)
print("\rI want to overwrite the first line")
print("I do not want to overwrite any line")
For more precise result wait for key press. and check out this code:
import msvcrt as m
def wait():
m.getch()
print("Overwrite this line", end="")
wait()
print("\rI want to overwrite the first line")
print("I do not want to overwrite any line")
Related
Here's the problem. In the following code, I wish to produce a 'moving cursor' effect. Here's the code:
sys.stdout.write('\033[2K\033[1G')
time.sleep(2)
print ('virus_prevention.fix.virus.|attempt_enter')
time.sleep(2)
sys.stdout.write('\033[2K\033[1G')
print ('virus_prevention.fix.virus|.attempt_enter')
time.sleep(0.1)
sys.stdout.write('\033[2K\033[1G')
print ('virus_prevention.fix.viru|s.attempt.enter')
time.sleep(0.1)
sys.stdout.write('\033[2K\033[1G')
print('virus_prevention.fix.vir|us.attempt.enter')
time.sleep(0.1)
sys.stdout.write('\033[2K\033[1G')
print ('virus_prevention.fix.vi|rus.attempt.enter')
time.sleep(0.1)
sys.stdout.write('\033[2K\033[1G')
print ('virus_prevention.fix.v|irus.attempt.enter')
time.sleep(0.1)
sys.stdout.write('\033[2K\033[1G')
print ('virus_prevention.fix.|virus.attempt.enter')
time.sleep(2)
sys.stdout.write('\033[2K\033[1G')
print ('virus_prevention.fix|virus.attempt.enter')
And this is the output:
[2K[1Gvirus_prevention.fix.virus.|attempt_enter
[2K[1Gvirus_prevention.fix.virus|.attempt_enter
[2K[1Gvirus_prevention.fix.viru|s.attempt.enter
[2K[1Gvirus_prevention.fix.vir|us.attempt.enter
[2K[1Gvirus_prevention.fix.vi|rus.attempt.enter
[2K[1Gvirus_prevention.fix.v|irus.attempt.enter
[2K[1Gvirus_prevention.fix.|virus.attempt.enter
And the sys.stdout.write doesn't really help. It just ends up with added text on the front of the current text. So if there are solutions anyone is willing to share (Python 3) please do. (I did have a solution which used repeatedly clearing the screen via os.system('clear'), which I don't really want to use.)
sys.stdout.write is a good start, but you also need to pass a "carriage return" '\r' to jump to the beginning of the line. This will overwrite the old characters with the next call:
for i in range(10):
sys.stdout.write(str(i)+'\r')
time.sleep(1)
If the new line is shorter than the previous line, you will still see the additional characters of the previous line. As a fix you can add some additional spaces to overwrite them.
The main difference between sys.stdout.write and print is, that print will automatically append a linebreak (\n). This is why you see the sys.stdout.write infront of the next printed line.
Running this in an interactive Python session has some weird side effects, but it is fine if you use it in a Python script. Also, make sure not to have any other print() commands inbetween. This only works on the current line, and any '\n' creates a new line.
sys.stdout.write('virus_prevention.fix.virus.|attempt_enter\r')
time.sleep(2)
sys.stdout.write('virus_prevention.fix.virus|.attempt_enter\r')
print() # create a linebreak at the end
This is similar to what you wish to achieve, you will need to adjust it to work with where you want the 'cursor' to show
import time
displayText = "Python"
character = '|'
for i in range(len(displayText)+1):
print(displayText[:i] + character + displayText[i:], end='\r')
time.sleep(.2)
input()
This will give the desired effect when executed via console/command prompt; but not through Python's IDLE Shell.
I am trying to clear only last few line from output console window. To achieve this I have decided to use create stopwatch and I have achieved to interrupt on keyboard interrupt and on enter key press it creates lap but my code only create lap once and my current code is clearing whole output screen.
clear.py
import os
import msvcrt, time
from datetime import datetime
from threading import Thread
def threaded_function(arg):
while True:
input()
lap_count = 0
if __name__ == "__main__":
# thread = Thread(target = threaded_function)
# thread.start()
try:
while True:
t = "{}:{}:{}:{}".format(datetime.now().hour, datetime.now().minute, datetime.now().second, datetime.now().microsecond)
print(t)
time.sleep(0.2)
os.system('cls||clear') # I want some way to clear only previous line instead of clearing whole console
if lap_count == 0:
if msvcrt.kbhit():
if msvcrt.getwche() == '\r': # this creates lap only once when I press "Enter" key
lap_count += 1
print("lap : {}".format(t))
time.sleep(1)
continue
except KeyboardInterrupt:
print("lap stop at : {}".format(t))
print(lap_count)
when I run
%run <path-to-script>/clear.py
in my ipython shell I am able to create only one lap but it is not staying for permanent.
To clear only a single line from the output :
print ("\033[A \033[A")
This will clear the preceding line and will place the cursor onto the beginning of the line.
If you strip the trailing newline then it will shift to the previous line as \033[A means put the cursor one line up
I think the simplest way is to use two print() to achieve clean the last line.
print("something will be updated/erased during next loop", end="")
print("\r", end="")
print("the info")
The 1st print() simply make sure the cursor ends at the end of the line and not start a new line
The 2nd print() would move the cursor to the beginning of the same line and not start a new line
Then it comes naturally for the 3rd print() which simply start print something where the cursor is currently at.
I also made a toy function to print progress bar using a loop and time.sleep(), go and check it out
def progression_bar(total_time=10):
num_bar = 50
sleep_intvl = total_time/num_bar
print("start: ")
for i in range(1,num_bar):
print("\r", end="")
print("{:.1%} ".format(i/num_bar),"-"*i, end="")
time.sleep(sleep_intvl)
The codes shared by Ankush Rathi above this comment are probably correct, except for the use of parenthesis in the print command. I personally recommend doing it like this.
print("This message will remain in the console.")
print("This is the message that will be deleted.", end="\r")
One thing to keep in mind though is that if you run it in IDLE by pressing F5, the shell will still display both messages. However, if you run the program by double clicking, the output console will delete it. This might be the misunderstanding that happened with Ankush Rathi's answer (in a previous post).
I know this is a really old question but i couldn't find any good answer at it. You have to use escape characters. Ashish Ghodake suggested to use this
print ("\033[A \033[A")
But what if the line you want to remove has more characters than the spaces in the string?
I think the better thing is to find out how many characters can fit in one of your terminal's lines and then to add the correspondent number of " " in the escape string like this.
import subprocess, time
tput = subprocess.Popen(['tput','cols'], stdout=subprocess.PIPE)
cols = int(tput.communicate()[0].strip()) # the number of columns in a line
i = 0
while True:
print(i)
time.sleep(0.1)
print("\033[A{}\033[A".format(' '*cols))
i += 1
finally I would say that the "function" to remove last line is
import subprocess
def remove():
tput = subprocess.Popen(['tput','cols'], stdout=subprocess.PIPE)
cols = int(tput.communicate()[0].strip())
print("\033[A{}\033[A".format(' '*cols))
For Python 3's, using f-String.
from time import sleep
for i in range(61):
print(f"\r{i}", end="")
sleep(0.1)
Found a solution on this page that works. Here is the helper function:
import sys
def delete_last_line():
"Deletes the last line in the STDOUT"
# cursor up one line
sys.stdout.write('\x1b[1A')
# delete last line
sys.stdout.write('\x1b[2K')
I hope it helps someone.
None of the other answers worked for me. Putting print("Sentence to be overwritten", end='\r') would instantly clear my sentence and it would never be visible to begin with. I'm using PyCharm on a Mac if that could be making the difference. What I had to do is the following:
from time import sleep
print("Sentence to be overwritten", end='')
sleep(1)
print("\r", end='')
print("Sentence to stay")
end='' makes it so the print doesn't automatically put a '\n' character at the end. Then print("\r", end='') will put the cursor at the beginning of the line. Then the 2nd print statement will be printed in the same spot as the first, overwriting it.
If you intend to delete certain line from the console output,
print "I want to keep this line"
print "I want to delete this line",
print "\r " # this is going to delete previous line
or
print "I want to keep this line"
print "I want to delete this line\r "
I'm pretty new to Python programming, and I'm attempting to create a simple little game with a little "initialization" on boot up.
I pretty much want it to spell out "Welcome", but with all of the letters popping up every 100ms.
I've got the sleep function down pat, however, rather than adding on each character to the end of the previous line, it is simply printing it all out on a new line.
This is what I'm currently getting:
W
e
l
c
o
m
e
.
I'd prefer it to just be Welcome.
This is my current code:
print("W")
time.sleep(0.1)
print("e")
time.sleep(0.1)
print("l")
time.sleep(0.1)
print("c")
time.sleep(0.1)
print("o")
time.sleep(0.1)
print("m")
time.sleep(0.1)
print("e")
I have looked around, but have failed to understand how to implement the function into Python. So an explanation would be extremely appreciated!
Thanks.
Use end='' when calling print():
import time
for c in "Welcome":
print(c, end='')
time.sleep(0.1)
Python's print() function normally prints outputs on a new line, meaning that every time you print something, it appears on another line. To print everything on the same line, as you're asking, use the print() function like this:
print("W", end="")
Notice the second argument which tells Python to continue printing on the same line. The print() function defaults to an ending of \n, or new line. Setting end equal to "" replaced the \n with an empty string.
In the event that you need to use the print() function after you print out "Welcome", the last print() function you use to print out the 'e' should be normal, like this:
print("e")
This way if you print anything after "Welcome", it will print on a new line.
How about this -
for c in "Welcome":
print '\b%s' % c,
time.sleep(0.1)
This question already has an answer here:
Why doesn't print output show up immediately in the terminal when there is no newline at the end?
(1 answer)
Closed last month.
I was trying to create a progress-like thing by printing a dot every second on the same line. Something like "Fishing.....". This is what I used:
import time
print('Fishing', end='')
for i in range(5):
time.sleep(1)
print('.', end='')
But it waits for 5 seconds and prints Fishing..... all at once. But when I don't use the end='', it prints dots every second, but on separate lines like so
Fishing.
.
.
.
.
My questions:
Why does print behave this way?
How can I print a dot every second, but on the same line?
Why does print behave this way?
This has less to do with print and more with your terminal. For performance reasons, the text only gets "flushed" everytime there's a newline character, and not one character at a time.
How can I print a dot every second, but on the same line?
By "flushing" the standard output manually everytime you printed something:
import time
import sys
print('Fishing', end='')
sys.stdout.flush()
for i in range(5):
time.sleep(1)
print('.', end='', flush=True) # another way
If you need this all the time, you could define a seperate flushing print function:
from functools import partial
myprint = partial(print, end='', flush=True)
myprint('Fishing')
for i in range(5):
time.sleep(1)
myprint('.')
This is because print is considered to be an expensive operation: it will usually wait until it has to print a lot of data, or until a new line is encountered (usually only if output is written to a terminal):
Output buffering is determined by file. Use file.flush() to ensure, for instance, immediate appearance on a screen.
Evidently it is not expensive in the sense that it takes minutes: but asking the terminal operator to print new content, or the operating system to write data to a file (in case of I/O redirection) is still not "lightning fast".
You can force to print all data that is still in the queue, by using a flush on the standard output channel.
use
print('.', end="", flush=True)
Im new to python and was wondering how to make a loading animation while my program runs. I need this because I don't want users thinking that the program is caught in a dead loop. I prefer a something like...
Loading...(with the dots disappearing and reappearing one by one)
Thanks!
If your output window supports the carriage return character, you can print it to make the cursor return to the beginning of the current line (provided you end your print statement with a comma, so a newline character isn't automatically printed). Then subsequent prints will overwrite what was already printed. You can use this to do very simple one line animation. Example:
import time
print "Starting program."
print "Loading ",
time.sleep(1) #do some work here...
print "\rLoading. ",
time.sleep(1) #do some more work here...
print "\rLoading.. ",
time.sleep(1) #do even more work...
print "\rLoading...",
time.sleep(1) #gratuitious amounts of work...
print "\rLoading ",
... Where time.sleep(1) is a placeholder representing the actual work you want to do.
Result:
Starting program.
Loading
Then, one second later:
Starting program.
Loading.
Then, one second later:
Starting program.
Loading..
Then, one second later:
Starting program.
Loading...
Then, one second later:
Starting program.
Loading
etc.
Compatibility note: in 3.X, print is no longer a statement, and the "end with a comma" trick no longer works. Instead, specify the end parameter:
print("\rLoading...", end="")
The most proper way I can think of to do it would be using threading.
You would initiate a thread that starts displaying some indication that the program is doing something and then open a new thread that actually does the work.
When the thread doing the work finished then you can move on with whatever else the program does.
This looks ok when ran in windows command prompt, not sure how linux will like it:
import threading
import time
import os
import queue
q = queue.Queue()
q.put(False)
class counter(object):
def __init__(self):
wait_label = "Loading"
self.stop_flag = q.get()
while not self.stop_flag:
try:
self.stop_flag = q.get_nowait()
except:
pass
os.system('cls') # might need to change this command for linux
wait_label += "."
print(wait_label)
time.sleep(1)
class other(counter):
def __init__(self):
time.sleep(15)
q.put(True)
counter_thread = threading.Thread(None, counter)
counter_thread.start()
other_thread = threading.Thread(None, other)
other_thread.start()
To reduce the code length, we can loop it.
import time
# flag variable to print the dots and it's value increases inside the while loop.
flag = 1
# To print the dots we use while loop. In total, 4 dots will be printed.
while flag < 5:
print("\rLoading, Please Wait " + ("." * flag), end=" ")
time.sleep(1)
flag = flag + 1