Save a subplot in matplotlib

Question

Is it possible to save (to a png) an individual subplot in a matplotlib figure? Let's say I have

import pyplot.matplotlib as plt ax1 = plt.subplot(121) ax2 = plt.subplot(122) ax1.plot([1,2,3],[4,5,6])     ax2.plot([3,4,5],[7,8,9]) 

Is it possible to save each of the two subplots to different files or at least copy them separately to a new figure to save them?

I am using version 1.0.0 of matplotlib on RHEL 5.

Answer 1

While @Eli is quite correct that there usually isn't much of a need to do it, it is possible. savefig takes a bbox_inches argument that can be used to selectively save only a portion of a figure to an image.

Here's a quick example:

import matplotlib.pyplot as plt import matplotlib as mpl import numpy as np  # Make an example plot with two subplots... fig = plt.figure() ax1 = fig.add_subplot(2,1,1) ax1.plot(range(10), 'b-')  ax2 = fig.add_subplot(2,1,2) ax2.plot(range(20), 'r^')  # Save the full figure... fig.savefig('full_figure.png')  # Save just the portion _inside_ the second axis's boundaries extent = ax2.get_window_extent().transformed(fig.dpi_scale_trans.inverted()) fig.savefig('ax2_figure.png', bbox_inches=extent)  # Pad the saved area by 10% in the x-direction and 20% in the y-direction fig.savefig('ax2_figure_expanded.png', bbox_inches=extent.expanded(1.1, 1.2)) 

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The full figure:

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Area inside the second subplot:

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Area around the second subplot padded by 10% in the x-direction and 20% in the y-direction: