Matplotlib – Calling pylab.savefig without display in ipython

ipython-notebookmatplotlib

I need to create a figure in a file without displaying it within IPython notebook. I am not clear on the interaction between IPython and matplotlib.pylab in this regard. But, when I call pylab.savefig("test.png") the current figure get's displayed in addition to being saved in test.png. When automating the creation of a large set of plot files, this is often undesirable. Or in the situation that an intermediate file for external processing by another app is desired.

Not sure if this is a matplotlib or IPython notebook question.

Best Answer

This is a matplotlib question, and you can get around this by using a backend that doesn't display to the user, e.g. 'Agg':

import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt

plt.plot([1,2,3])
plt.savefig('/tmp/test.png')

EDIT: If you don't want to lose the ability to display plots, turn off Interactive Mode, and only call plt.show() when you are ready to display the plots:

import matplotlib.pyplot as plt

# Turn interactive plotting off
plt.ioff()

# Create a new figure, plot into it, then close it so it never gets displayed
fig = plt.figure()
plt.plot([1,2,3])
plt.savefig('/tmp/test0.png')
plt.close(fig)

# Create a new figure, plot into it, then don't close it so it does get displayed
plt.figure()
plt.plot([1,3,2])
plt.savefig('/tmp/test1.png')

# Display all "open" (non-closed) figures
plt.show()
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