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display `print` in callbacks in the notebook

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#116 8 comments 1 reaction 0 assignees View on GitHub

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
jupyter, jupyter-notebook, python

Research direction

The issue provides a Python callback using fig.canvas.mpl_connect and an ipywidgets.Output workaround; start by reproducing the missing print output in JupyterLab with ipympl and compare it with IPython. Done means print output from matplotlib callbacks appears automatically in the notebook without wrapping the callback in an Output context.

Written by the indexing model from the issue text.

Description

import matplotlib.pyplot as plt

fig, ax = plt.subplots()
n = 0

def printer(event):
    global n
    print(f'in event {event}')
    n += 1
 

fig.canvas.mpl_connect('button_press_event', printer)

when run in IPython prints out to stdout on every mouse click. In jlab + ipympl the prints don't show up anywhere I can find...

From https://ipywidgets.readthedocs.io/en/stable/examples/Output%20Widget.html it looks like this can work via:

output = widgets.Output()
display(fig.canvas, output)

n = 0
def printer(event):
    global n
    with output:
        print(f'in event {event}')
    n += 1
    
fig.canvas.mpl_connect('button_press_event', printer)

but I suspect there is a way for this to work automatically....

Dominant language
Jupyter Notebook
Stars
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Forks
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PR merge metrics
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