I am very new to Python and I would like to know how I would clear a text that has been printed and add another piece of text. For example, I would like to display "Hello" then program with a delay of 10 seconds to replace text with another text "Goodbye". I am using Python 3.3 on Windows 7.
import time
import os
print ('hello there')
time.sleep(10) # this will BLOCK your program for 10 seconds
os.system('cls') # clear the screen, since cls is the clear screen command for windows
print ('bye')
input() # this is to wait to user to enter something to exist
version 2, using some 'visual' effects :D
import time
import os
print ('hello there')
for i in range(1, 10):
time.sleep(1)
print ('.')
os.system('cls')
print ('bye')
input()
Once text is sent to stdout, there really isn't a good way to change it. What you probably want to do would require a UI library such as tkinter (which comes with Python) or wxPython. Then you can create a Window with a label widget that can change every few seconds. You might be able to use Python's curses library too, but I have yet to see a coherent tutorial on how you would use that for this sort of thing.
Python's output is based on an abstraction of "output is just a file that you can write to", so there's no way to do this cross-platform.
However, if you want it to work in a Windows cmd.exe console (aka "DOS prompt"), and don't care about working inside IDLE, on Unix, over a network, etc., you can use the MSVCRT console I/O APIs.
Unfortunately, the limited set of console I/O APIs built into the standard library doesn't include the clear function. But you can look for third-party extended console I/O libraries on PyPI, or use PyWin32 to call the MSVCRT functions directly.
Or you can use a cheap hack:
import subprocess
subprocess.check_call(['cls'])
This just calls the cls function, which does everything for you.
Edit: the linked post does not solve this problem, this is still an outstanding issue.
I execute the following program in Spyder with iPython:
import time
print "Please enter your name."
userName=raw_input();
print "Now let's wait a few seconds, {}.".format(userName)
time.sleep(1)
print "Did you lose your patience?"
It prompts the user for their name, then (instead of printing the first line, waiting, and then printing the second line), it pauses and then prints the outputs of the last two print statements at the same time.
When I run from the command line, it works as expected. So does anyone know what I can do so that the script shows the desired behavior from within Spyder/iPython (I am working in Windows 7, Spyder 2.2.5 running iPython with Python 2.7).
Note because I get the expected behavior when I run from the command line, the suggestion at Why is time.sleep pausing early? is not transparently applicable, but perhaps it is easy to port that solution to this case? Also, running 'sys.stdout.flush()' before the sleep command doesn't seem to do anything.
I tested this in Spyder and vanza's solution works for me. Are you sure you put sys.stdout.flush() in the right line? It should look like this:
vanza's solution:
import time
import sys
print "Please enter your name."
userName=raw_input();
print "Now let's wait a few seconds, {}.".format(userName)
sys.stdout.flush() # <- *** it goes here ***
time.sleep(3)
print "Did you lose your patience?"
You might want to scroll down the iPython console a bit before entering your input, to see the text clearly (otherwise it stays a bit low to be noticed).
This question already has answers here:
How to keep a Python script output window open?
(27 answers)
Closed 9 years ago.
I am trying to learn python and for that purpose i made a simple addition program using python 2.7.3
print("Enter two Numbers\n")
a = int(raw_input('A='))
b = int(raw_input('B='))
c=a+b
print ('C= %s' %c)
i saved the file as add.py and when i double click and run it;the program run and exits instantenously without showing answer.
Then i tried code of this question Simple addition calculator in python it accepts user inputs but after entering both numbers the python exits with out showing answer.
Any suggestions for the above code. Advance thanks for the help
add an empty raw_input() at the end to pause until you press Enter
print("Enter two Numbers\n")
a = int(raw_input('A='))
b = int(raw_input('B='))
c=a+b
print ('C= %s' %c)
raw_input() # waits for you to press enter
Alternatively run it from IDLE, command line, or whichever editor you use.
It's exiting because you're not telling the interpreter to pause at any moment after printing the results. The program itself works. I recommend running it directly in the terminal/command line window like so:
Alternatively, you could write:
import time
print("Enter two Numbers\n")
a = int(raw_input('A='))
b = int(raw_input('B='))
c=a+b
print ('C= %s' %c)
time.sleep(3.0) #pause for 3 seconds
Or you can just add another raw_input() at the end of your code so that it waits for input (at which point the user will type something and nothing will happen to their input data).
Run your file from the command line. This way you can see exceptions.
Execute cmd than in the "dos box" type:
python myfile.py
Or on Windows likley just:
myfile.py
Short Question
Is it possible/practical to write and update a multi-line (contains \n) string on a Windows terminal?
Background
I have looked into curses, but it is Unix only. I saw a few other Window ports, but it was a bit troubling that Windows XP was an experimental OS for one them. I am hoping to use this as part of a diagnostic feature to display link status, message rates, etc on a mainly terminal application (note that some variants do have a wxPython GUI input). That being said, using Cygwin is non-ideal and would love to find a workaround using only the sys module.
I have tried the following: (note that I expected them to fail, but hoped I would be wrong)
Attempt 1: Updates the string but it is all on 1 line
sys.stdout.write("\r")
sys.stdout.write("This is a multi-line screen print test")
sys.stdout.write("Line 1")
sys.stdout.write("Line 2")
sys.stdout.flush()
Attempt 2: Does not update but prints all the lines
sys.stdout.write("\r")
sys.stdout.write("This is a multi-line screen print test\n")
sys.stdout.write("Line 1 \n")
sys.stdout.write("Line 2\n")
sys.stdout.flush()
The closest thing I could find to curses (that has been updated in the last 10 years) was Windows Console Driver. Rather than use this approach I went at it was a less elegant method.
import os
import time
while(1):
time.sleep(.05)
os.system('cls')
print "This is a multi-line screen print test"
print "Line 1"
print "Line 2"
You might have to use the Windows Console API. For example, SetConsoleCursorPosition. Other people appear to have implemented Python modules to support this API: 1, 2
I have just started with Python. When I execute a python script file on Windows, the output window appears but instantaneously goes away. I need it to stay there so I can analyze my output. How can I keep it open?
You have a few options:
Run the program from an already-open terminal. Open a command prompt and type:
python myscript.py
For that to work you need the python executable in your path. Just check on how to edit environment variables on Windows, and add C:\PYTHON26 (or whatever directory you installed python to).
When the program ends, it'll drop you back to the cmd prompt instead of closing the window.
Add code to wait at the end of your script. For Python2, adding ...
raw_input()
... at the end of the script makes it wait for the Enter key. That method is annoying because you have to modify the script, and have to remember removing it when you're done. Specially annoying when testing other people's scripts. For Python3, use input().
Use an editor that pauses for you. Some editors prepared for python will automatically pause for you after execution. Other editors allow you to configure the command line it uses to run your program. I find it particularly useful to configure it as "python -i myscript.py" when running. That drops you to a python shell after the end of the program, with the program environment loaded, so you may further play with the variables and call functions and methods.
cmd /k is the typical way to open any console application (not only Python) with a console window that will remain after the application closes. The easiest way I can think to do that, is to press Win+R, type cmd /k and then drag&drop the script you want to the Run dialog.
Start the script from an already open cmd window or
at the end of the script add something like this, in Python 2:
raw_input("Press enter to exit;")
Or, in Python 3:
input("Press enter to exit;")
To keep your window open in case of exception (yet, while printing the exception)
Python 2
if __name__ == '__main__':
try:
## your code, typically one function call
except Exception:
import sys
print sys.exc_info()[0]
import traceback
print traceback.format_exc()
print "Press Enter to continue ..."
raw_input()
To keep the window open in any case:
if __name__ == '__main__':
try:
## your code, typically one function call
except Exception:
import sys
print sys.exc_info()[0]
import traceback
print traceback.format_exc()
finally:
print "Press Enter to continue ..."
raw_input()
Python 3
For Python3 you'll have to use input() in place of raw_input(), and of course adapt the print statements.
if __name__ == '__main__':
try:
## your code, typically one function call
except BaseException:
import sys
print(sys.exc_info()[0])
import traceback
print(traceback.format_exc())
print("Press Enter to continue ...")
input()
To keep the window open in any case:
if __name__ == '__main__':
try:
## your code, typically one function call
except BaseException:
import sys
print(sys.exc_info()[0])
import traceback
print(traceback.format_exc())
finally:
print("Press Enter to continue ...")
input()
you can combine the answers before: (for Notepad++ User)
press F5 to run current script and type in command:
cmd /k python -i "$(FULL_CURRENT_PATH)"
in this way you stay in interactive mode after executing your Notepad++ python script and you are able to play around with your variables and so on :)
Create a Windows batch file with these 2 lines:
python your-program.py
pause
Using atexit, you can pause the program right when it exits. If an error/exception is the reason for the exit, it will pause after printing the stacktrace.
import atexit
# Python 2 should use `raw_input` instead of `input`
atexit.register(input, 'Press Enter to continue...')
In my program, I put the call to atexit.register in the except clause, so that it will only pause if something went wrong.
if __name__ == "__main__":
try:
something_that_may_fail()
except:
# Register the pause.
import atexit
atexit.register(input, 'Press Enter to continue...')
raise # Reraise the exception.
In python 2 you can do it with: raw_input()
>>print("Hello World!")
>>raw_input('Waiting a key...')
In python 3 you can do it with: input()
>>print("Hello world!")
>>input('Waiting a key...')
Also, you can do it with the time.sleep(time)
>>import time
>>print("The program will close in 5 seconds")
>>time.sleep(5)
On Python 3
input('Press Enter to Exit...')
Will do the trick.
You can just write
input()
at the end of your code
therefore when you run you script it will wait for you to enter something
{ENTER for example}
I had a similar problem. With Notepad++ I used to use the command : C:\Python27\python.exe "$(FULL_CURRENT_PATH)" which closed the cmd window immediately after the code terminated.
Now I am using cmd /k c:\Python27\python.exe "$(FULL_CURRENT_PATH)" which keeps the cmd window open.
To just keep the window open I agree with Anurag and this is what I did to keep my windows open for short little calculation type programs.
This would just show a cursor with no text:
raw_input()
This next example would give you a clear message that the program is done and not waiting on another input prompt within the program:
print('You have reached the end and the "raw_input()" function is keeping the window open')
raw_input()
Note!
(1) In python 3, there is no raw_input(), just
input().
(2) Use single quotes to indicate a string; otherwise if you type doubles around anything, such as
"raw_input()", it will think it is a function, variable, etc, and not text.
In this next example, I use double quotes and it won't work because it thinks there is a break in the quotes between "the" and "function" even though when you read it, your own mind can make perfect sense of it:
print("You have reached the end and the "input()" function is keeping the window open")
input()
Hopefully this helps others who might be starting out and still haven't figured out how the computer thinks yet. It can take a while. :o)
If you want to run your script from a desktop shortcut, right click your python file and select Send to|Desktop (create shortcut). Then right click the shortcut and select Properties. On the Shortcut tab select the Target: text box and add cmd /k in front of the path and click OK. The shortcut should now run your script without closing and you don't need the input('Hit enter to close')
Note, if you have more than one version of python on your machine, add the name of the required python executable between cmd /k and the scipt path like this:
cmd /k python3 "C:\Users\<yourname>\Documents\your_scipt.py"
Apart from input and raw_input, you could also use an infinite while loop, like this:
while True: pass (Python 2.5+/3) or while 1: pass (all versions of Python 2/3). This might use computing power, though.
You could also run the program from the command line. Type python into the command line (Mac OS X Terminal) and it should say Python 3.?.? (Your Python version) It it does not show your Python version, or says python: command not found, look into changing PATH values (enviromentl values, listed above)/type C:\(Python folder\python.exe. If that is successful, type python or C:\(Python installation)\python.exe and the full directory of your program.
A very belated answer, but I created a Windows Batch file called pythonbat.bat containing the following:
python.exe %1
#echo off
echo.
pause
and then specified pythonbat.bat as the default handler for .py files.
Now, when I double-click a .py file in File Explorer, it opens a new console window, runs the Python script and then pauses (remains open), until I press any key...
No changes required to any Python scripts.
I can still open a console window and specify python myscript.py if I want to...
(I just noticed #maurizio already posted this exact answer)
If you want to stay cmd-window open AND be in running-file directory this works at Windows 10:
cmd /k cd /d $(CURRENT_DIRECTORY) && python $(FULL_CURRENT_PATH)
I found the solution on my py3 enviroment at win10 is just run cmd or powershell as Administrator,and the output would stay at the same console window,any other type of user run python command would cause python to open a new console window.
The simplest way:
your_code()
while True:
pass
When you open the window it doesn't close until you close the prompt.
`import sys,traceback
sys.exc_info()[0]
traceback.format_exc()
print("Press Enter to exit ...")
input()`
simply write the above code after your actual code. for eg. am taking input from user and print on console hence my code will be look like this -->
`import sys,traceback
nam=input("enter your name:")
print("your name is:-{}".format(nam)) #here all my actual working is done
sys.exc_info()[0]
traceback.format_exc()
print("Press Enter to exit ...")
input()`
Try this,
import sys
stat='idlelib' in sys.modules
if stat==False:
input()
This will only stop console window, not the IDLE.
You can launch python with the -i option or set the environment variable PYTHONINSPECT=x. From the docs:
inspect interactively after running script; forces a prompt even
if stdin does not appear to be a terminal; also PYTHONINSPECT=x
So when your script crashes or finishes, you'll get a python prompt and your window will not close.
Create a function like dontClose() or something with a while loop:
import time
def dontClose():
n = 1
while n > 0:
n += 1
time.sleep(n)
then run the function after your code. for e.g.:
print("Hello, World!")
dontClose()
Go here and download and install Notepad++
Go here and download and install Python 2.7 not 3.
Start, Run Powershell. Enter the following. [Environment]::SetEnvironmentVariable("Path", "$env:Path;C:\Python27", "User")
Close Powershell and reopen it.
Make a directory for your programs. mkdir scripts
Open that directory cd scripts
In Notepad++, in a new file type: print "hello world"
Save the file as hello.py
Go back to powershell and make sure you are in the right directory by typing dir. You should see your file hello.py there.
At the Powershell prompt type: python hello.py
On windows 10 insert at beggining this:
#!/usr/bin/env python
# -*- coding: utf-8 -*-
Strange, but it work for me!(Together with input() at the end, of course)
You can open PowerShell and type "python".
After Python has been imported, you can copy paste the source code from your favourite text-editor to run the code.
The window won't close.
A simple hack to keep the window open:
counter = 0
While (True):
If (counter == 0):
# Code goes here
counter += 1
The counter is so the code won’t repeat itself.
The simplest way:
import time
#Your code here
time.sleep(60)
#end of code (and console shut down)
this will leave the code up for 1 minute then close it.