Python Matplotlib, retain plot after command line script ends

Question

After many hours searching I am looking for a straightforward answer to the question... "Is there ANY way to run a Python3 script from the command line, which generates a plot, and have the plot remain on-screen after the script ends"?

Ideally I would love to leave the plot running in the background, and have it remain interactive enough to allow for zooming, panning and resizing (don't care cabout updating data ... yet), but I'll settle for something as low-tech as just leaving the plot there, so I can rerun the same script with different data, so I can compare plots (ya, I know I can run the entire py script in the background if necessary, which is less elegant, but may be necessary).

Some possibilities that have some to mind that may or may not be possible: have the main script spawn a background/detached process that does the plotting; use threading; keep the script running while I want to zoom/pan/resize, then leave the plot in a static state (like a picture) when the script ends.

Tried maybe a dozen or so methods posted, but none work so far.

If it can't be done, please someone just give a short and simple answer that says so, so I can move on and kludge something together like writing an image file, and spawning a background shell that that displays a picture. Or possibly, going back to something low-tech like Bash, which will allow me to use GNUplot (yup, that works amazingly ok compared to matpltlib, so far).

Thanks to anyone who can save my sanity.

-G

Here is some of what I tried from other posts:

plt.show(block=False) will not even show a plot unless preceeded by a plt.pause(). even plt.draw() does not produce a plot. only plt.pause() before the plt.show(block=False) gives me a plot, and then the plot closes when the script ends

plt.pause(0.01) allows for zooming/resizing/etc while in a loop (which I can live with), but no way to leave (even a static plot) after the script ends. This is usable, if I can leave the plot on-screen after the script ends.

plt.draw(), plt.ion() gives anomalous results, including blank plots or no plots at all

No you cannot do this. You cannot keep part of a program running after it has stopped running. Why do you want the script to end? If you want to plot more figures, just run the script again, either from the same command line after putting the process in the background, or from another command line. — Jody Klymak
– Jody Klymak, Commented Jan 27, 2023 at 2:09

Chris · Accepted Answer · 2023-01-27 00:33:02Z

1

You could just open the saved image figure, for example in this post

import sys
import subprocess

def openImage(path):
    imageViewerFromCommandLine = {'linux':'xdg-open',
                                  'win32':'explorer',
                                  'darwin':'open'}[sys.platform]
    subprocess.Popen([imageViewerFromCommandLine, path])

import matplotlib.pyplot as plt
import numpy as np

# Data for plotting
t = np.arange(0.0, 2.0, 0.01)
s = 1 + np.sin(2 * np.pi * t)

fig, ax = plt.subplots()
ax.plot(t, s)

ax.set(xlabel='time (s)', ylabel='voltage (mV)',
       title='About as simple as it gets, folks')
ax.grid()

fig.savefig("test.png")

openImage('test.png')

answered Jan 27, 2023 at 0:33

Chris

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gboffi · Accepted Answer · 2023-01-27 14:49:37Z

0

Just use background execution.

answered Jan 27, 2023 at 14:49

gboffi

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gboffi Over a year ago

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