ipython notebook clear cell output in code

Question

In a iPython notebook, I have a while loop that listens to a Serial port and print the received data in real time.

What I want to achieve to only show the latest received data (i.e only one line showing the most recent data. no scrolling in the cell output area)

What I need(i think) is to clear the old cell output when I receives new data, and then prints the new data. I am wondering how can I clear old data programmatically ?

cel · Accepted Answer · 2020-02-11T16:05:31.537

371

You can use IPython.display.clear_output to clear the output of a cell.

from IPython.display import clear_output

for i in range(10):
    clear_output(wait=True)
    print("Hello World!")

At the end of this loop you will only see one Hello World!.

Without a code example it's not easy to give you working code. Probably buffering the latest n events is a good strategy. Whenever the buffer changes you can clear the cell's output and print the buffer again.

edited Feb 11 '20 at 16:05

answered Jul 18 '14 at 06:12

cel

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Simplest ajax interface ever! – Unni Mar 28 '17 at 20:52
67

Using the `clear_output(wait=True)` will generally make the result nicer if you have `clear_output` inside a loop. – Toke Faurby Jun 08 '17 at 23:49
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half of the screen after the print result shakes, but shake less thanks to the wait=True – B.Mr.W. Aug 12 '18 at 04:26
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But this clears all the output. Is there a way to clear only the most recent figure? Edit: this is what I was looking for: https://github.com/jupyter-widgets/ipywidgets/issues/1744#issuecomment-335179855 – Solomon Vimal Jul 18 '19 at 00:13
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Why are we looping? What's with `i`? – jorijnsmit Dec 18 '19 at 16:38
2

@jorijnsmit, just to illustrate that "Hello World!" is not printed 10 times, but just 1 time. `i` doesn't really matter. – cel Dec 18 '19 at 17:45

score 9 · Answer 2 · answered Sep 03 '19 at 13:11

You can use the IPython.display.clear_output to clear the output as mentioned in cel's answer. I would add that for me the best solution was to use this combination of parameters to print without any "shakiness" of the notebook:

from IPython.display import clear_output

for i in range(10):
    clear_output(wait=True)
    print(i, flush=True)

score 3 · Answer 3 · answered Jul 11 '21 at 17:52

3

You can have a better visualization of the function clear_output(wait=True) with this simple code.

from IPython.display import clear_output
import time 

for i in tqdm(range(10)):
    clear_output(wait=True)
    print(i)
    time.sleep(1)

answered Jul 11 '21 at 17:52

vaibhav singh

55
5

score 2 · Answer 4 · answered Jun 10 '19 at 21:08

And in case you come here, like I did, looking to do the same thing for plots in a Julia notebook in Jupyter, using Plots, you can use:

    IJulia.clear_output(true)

so for a kind of animated plot of multiple runs

    if nrun==1  
      display(plot(x,y))         # first plot
    else 
      IJulia.clear_output(true)  # clear the window (as above)
      display(plot!(x,y))        # plot! overlays the plot
    end

Without the clear_output call, all plots appear separately.

score 1 · Answer 5 · answered Aug 05 '21 at 15:22

1

If I am not wrong you mean you just need to clear the output part of a cell, which could be a valid output or some error which you don't what to look anymore. If Yes! just go to top ribbon and select Cell > Current Outputs > Clear

answered Aug 05 '21 at 15:22

VinitV

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That should work for interactive clearing of the cell, but OP asked for a programmatic way to do this. – joanis Aug 05 '21 at 17:17

score 0 · Answer 6 · answered May 09 '22 at 18:42

0

Simple, if you want to clear the output of that current cell only just use this at the end of that cell

from IPython.display import clear_output
clear_output(wait=False)

answered May 09 '22 at 18:42

Deepanshu Mehta

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ipython notebook clear cell output in code

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