Saving matplotlib figure with add_axes

Question

I'm trying to save a figure with an extra image on top. However Python only saves the bottom figure. I have:

fig = plt.figure(figsize=(8, 6))
ax = fig.add_subplot(111)

ax.plot(...)
...

ax_im = fig.add_axes([0.1, 1.0, 1, 1])
ax_im.set_xticks([])
ax_im.set_yticks([])

ax.imshow(...)
...

fig.savefig('image.png')

and Matplotlib only saves the figure related to the ax axis. In the iPython notebook the output is fine, it shows both figures, So, I don't know whats happening.

Answer 1

Try something like this

ax_im = fig.add_axes([0.1, 0.2, 0.5, 0.5], label='axes1')

The explanation is that your second parameter to add_axes is 1.0. This specifies the bottom ot the Axes at the top of the figure.

Following example works for me:

import pylab as plt

fig = plt.figure(figsize=(8, 6))
ax = fig.add_subplot(212)

ax.plot(range(3))

ax_im = fig.add_axes([0.3, 0.5, 0.5, 0.4])
ax_im.set_xticks([])
ax_im.set_yticks([])

plt.show()

or even easier, use add_subplot twice:

import pylab as plt

fig = plt.figure(figsize=(8, 6))
ax = fig.add_subplot(212)

ax.plot(range(3))

ax_im = fig.add_subplot(211)
ax_im.plot(range(3), 'o--')
ax_im.set_xticks([])
ax_im.set_yticks([])

plt.show()