pyplot: Closing a show() window doesn't continue code

Question

I have successfully been using pyplot to show heatmaps. Today it seems to have stopped working.

My problem is that setting up my plot, then calling the show() method shows the figure in a window, but when I close this window (by clicking the x at the top), my code doesn't continue past where the show() method is called. It seems to hang on show().

matrix is a numpy matrix.

This is an example of my code:

plt.pcolor(matrix, cmap=plt.cm.binary)
plt.xlabel('xaxis', fontsize=20)
plt.ylabel('yaxis', fontsize=20)
plt.axis([0, matrix.shape[1], 0, matrix.shape[0]])
plt.colorbar()
#This is where my code hangs...
plt.show()
#Closing the window manually does nothing.
#And the close() method doesn't seem to do anything.
plt.close()

After the show() method is called, and the window is closed, my process keeps going, and I have to manually terminate it.

Does anyone know the reason why this is happening?

Are you using this in ipython? What OS are you working on? Have you changed anything in your script or updated any packages that could have caused the problem? Could you provide a bit more details? — hitzg
– hitzg, Commented Jun 9, 2015 at 12:55

Brent Robertson · Accepted Answer · 2018-01-26 23:07:12Z

4

If you are using tkinter:

I ran into the same problem when using tkinter (to select the file with the data for the plots) in conjunction with pyplot. I have found that, by calling root.destroy on my tkinter.Tk() object, closing the window created by plt.show() allows my code to continue instead of hanging.

answered Jan 26, 2018 at 23:07

Brent Robertson

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Comments

tmdavison · Accepted Answer · 2015-06-08 17:02:20Z

1

have you tried setting plt.ion() sometime before plt.show(). That should set interactive mode, and show won't stop the execution of your script.

answered Jun 8, 2015 at 17:02

tmdavison

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6 Comments

Kestrel Over a year ago

When I add plt.ion() before plt.show(), the window appears briefly (long enough to see the figure, actually), and then closes by itself.

hitzg Over a year ago

@Kestrel Well in that case it closes because you call plt.close().

hitzg Over a year ago

This solution is a work-around, but not an answer to the question why show continues to block after closing the figure.

tmdavison Over a year ago

Agreed, just thought it might be useful in this case

Kestrel Over a year ago

@hitzg even when plt.close() is removed, it still exhibits the same blocking behaviour.

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Richard · Accepted Answer · 2017-09-11 02:29:38Z

0

because plt.show() is a "blocking function" and the code will not resume until you close the figure. it will not even get to plt.close() before you close the figure, as it is written after plt.show()

edited Sep 11, 2017 at 2:29

Richard

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answered Jun 7, 2017 at 10:47

Alon

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Comments

MacItaly · Accepted Answer · 2019-12-09 22:14:09Z

0

Just recently it looks as though you can do:

plt.show(block=False)

This will no longer block the code from continuing after the graph is closed.

answered Dec 9, 2019 at 22:14

MacItaly

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