matplotlib/matplotlib — pull request #3802 by mdboom (2014-11-17 18:50:17+00:00)
Title: Imsave AssertionError (empty bboxes)

Pyplot.imsave does not seem to work. The matplotlibrc file that I'm using: https://raw.githubusercontent.com/byuimpact/numerical_computing/develop/matplotlibrc
```python
import matplotlib
matplotlib.rcParams = matplotlib.rc_params_from_file("./matplotlibrc")

import numpy as np
import matplotlib.pyplot as plt
f = np.random.randint(0, 255, shape=(92,92))
plt.imsave("test.png", f)
```
results in an AssertionError
```
---------------------------------------------------------------------------
AssertionError Traceback (most recent call last)
in ()
----> 1 plt.imsave("test.pdf", f)

/usr/lib/python2.7/site-packages/matplotlib/pyplot.pyc in imsave(*args, **kwargs)
2218 @docstring.copy_dedent(_imsave)
2219 def imsave(*args, **kwargs):
-> 2220 return _imsave(*args, **kwargs)
2221
2222

/usr/lib/python2.7/site-packages/matplotlib/image.pyc in imsave(fname, arr, vmin, vmax, cmap, format, origin, dpi)
1312 canvas = FigureCanvas(fig)
1313 im = fig.figimage(arr, cmap=cmap, vmin=vmin, vmax=vmax, origin=origin)
-> 1314 fig.savefig(fname, dpi=dpi, format=format, transparent=True)
1315
1316

/usr/lib/python2.7/site-packages/matplotlib/figure.pyc in savefig(self, *args, **kwargs)
1468 self.set_frameon(frameon)
1469
-> 1470 self.canvas.print_figure(*args, **kwargs)
1471
1472 if frameon:

/usr/lib/python2.7/site-packages/matplotlib/backend_bases.pyc in print_figure(self, filename, dpi, facecolor, edgecolor, orientation, format, **kwargs)
2141 **kwargs)
2142 renderer = self.figure._cachedRenderer
-> 2143 bbox_inches = self.figure.get_tightbbox(renderer)
2144
2145 bbox_artists = kwargs.pop("bbox_extra_artists", None)

/usr/lib/python2.7/site-packages/matplotlib/figure.pyc in get_tightbbox(self, renderer)
1611 bb.append(ax.get_tightbbox(renderer))
1612
-> 1613 _bbox = Bbox.union([b for b in bb if b.width != 0 or b.height != 0])
1614
1615 bbox_inches = TransformedBbox(_bbox,

/usr/lib/python2.7/site-packages/matplotlib/transforms.pyc in union(bboxes)
720 Return a :class:`Bbox` that contains all of the given bboxes.
721 """
--> 722 assert(len(bboxes))
723
724 if len(bboxes) == 1:

AssertionError:
```

It appears that the ```Bbox.union()``` results in an empty list.

EDIT: Gave the correct sample that code that produces the error.