Matplotlib 图 window 在交互模式下消失

Question

I need to use interactive mode when plotting with matplotlib (it should be a script, not python or ipython console). But setting plt.ion() causes a strange bug (?). When I try to plot my figure (I don't think it really matters, what I do exactly, because in non-interactive mode it works perfectly fine) I don't see it - I get a blank grey window for split-second, which momentarily disappears and the programme exits. If I explicitly add plt.draw() (and plt.pause(1) to see the result), I see that the figure appears as expected. If I do the same after modifications I want to do to the figure when it is visible, the figure changes. But the window still disappears after the pause is over.

I run it in Spyder with Qt4Agg as a backend under Ubuntu. Tried running the script from terminal as python my_script.py , the result is identical.

What could be the problem? How do I stop the figure from disappearing when in interactive mode?

UPDATE

Working example:

import matplotlib.pyplot as plt
import numpy as np

plt.ion()

x = np.linspace(1, 10)
y = np.sin(x)
plt.plot(x, y)
plt.draw()
plt.pause(1)

If I run this code I see the sine plot for 1 second, then the window disappears.

UPDATE 2

I found a solution here: https://stackoverflow.com/a/10724654/1304161 If I set the run options in Spyder correctly, it works perfectly fine. Although running it in gnome-terminal doesn't work, I don't really need it. Hopefully, there won't be a problem with this when it becomes a part of a GUI app...

Answer 1

I found a solution here: https://stackoverflow.com/a/10724654/1304161

If I set the run options in Spyder correctly, it works perfectly fine. Although running it in gnome-terminal doesn't work, I don't really need it. Hopefully, there won't be a problem with this when it becomes a part of a GUI app. I will be back, if it will be a problem then :)

Answer 2

You can make it work by adding these two lines at the end:

plt.ioff()
plt.show()

So this program works fine:

import matplotlib.pyplot as plt
import numpy as np

plt.ion()

x = np.linspace(1, 10)
y = np.sin(x)
plt.plot(x, y)
plt.draw()
plt.ioff()
plt.show()

Answer 3

To display multiple figures at different times, you can use code.interact(local=locals()) , after plt.show() to pause the Python interpreter until a Ctrl-Z is pressed in the Python Shell:

import code
import matplotlib.pyplot as plt
import numpy as np

# Start pyplot's "interactive mode" which lets you run plt.show multiple times
plt.ion()

x = np.linspace(1, 10)
y = np.sin(x)

# PLOT #1 - displayed
plt.plot(x, y)
plt.draw()
plt.show()

# Wait for figure to be closed AND Ctrl-Z pressed in Python Shell
code.interact(local=locals())

print("Some more code can go here...")

# PLOT #2 - displayed
plt.plot(x, y)
plt.show()

# Wait for figure to be closed AND Ctrl-Z pressed in Python Shell
code.interact(local=locals())