在Jupyter Notebook中打印时如何在光标上存放信息

Question

I'd like to run the following code in Jupyter notebook:

from time import sleep

print("Something I won't update.")
for i in range(10):
    sleep(.5)
    print("a%d\nb%d" % (i, i+1), end="\033[A\r")

The targeted result is the following: it prints at time i=0 :

Something I won't update.
a0
b1

Then at time i=1 , the three lines above are replaced by:

Something I won't update.
a1
b2

And so forth and so on...

This works properly in a terminal but not in my notebook where the ANSI escape \\033[A is considered as an empty character '' . In other words, in Jupyter, I get at time i=0 :

Something I won't update.
a0
b1

And at time i=1 , the output is updated as follows:

Something I won't update.
a0
a1
b2

__EDIT__

Similar questions have been raised on Stack Overflow:

Overwrite previous output in jupyter notebook Overwrite previous output in Jupyter Notebook

How to overwrite the previous print line in Jupyter / IPython How to overwrite the previous print line in Jupyter IPython

However, they only cover the cases:

• How to rewrite a single line which can be handled by:

import sys
from time import sleep

print("Something I won't update.")
for i in range(10):
    sleep(.5)
    sys.stdout.write("\r%d" % i) 

This is not working with paragraphs (multiple lines). The behavior is the same than the one described above.

• How to rewrite the whole cell:

from IPython.display  import clear_output
from time import sleep

print("Something I won't update.")
for i in range(10):
    sleep(.5)
    clear_output(wait=True)
    print("a%d\nb%d" % (i, i+1))

Here the behavior is not the desired one as the line Something I won't update. will disappear. In a more practical usecase, I have other things to display like matplotlib figures that I don't want to remove.

The purpose of this question is to be able to rewrite several specific lines . Is there anyway to get the desired behavior in Jupyter ?

Answer 1

Try this in the jupyter notebook

from time import sleep
from IPython.display import clear_output
for i in range(10):
    sleep(.5)
    clear_output(wait=True)
    print("a%d\nb%d" % (i, i+1))