CODEWITHSUNDEEP
pythonmatplotlibplot
Osmond Bishop
Osmond Bishop

Reputation: 8180

Error with bbox_inches='tight' in matplotlib

I use the following piece of code in an ipython notebook to save a bar graph as a .png file:
plt.savefig(filename, bbox_inches='tight')

It works on my computer and I have tried running the script on another computer. However I get the following error when I try to run it on the other machine.

AssertionError
---> 119 plt.savefig(filename,bbox_inches='tight')

C:\Python27\lib\site-packages\matplotlib\pyplot.pyc in savefig(*args,**kwargs)
---> 472 self.canvas.print_figure(*args,**kwargs)

C:\Python27\lib\site-packages\matplotlib\figure.pyc in savefig(self,*args,**kwargs)
---> 1363 self.canvas.print_figure(*args,**kwargs)

C:\Python27\lib\site-packages\matplotlib\backend_bases.pyc
---> 2054 bbox_inches = self.figure.get_tightbbox(renderer)

C:\Python27\lib\site-packages\matplotlib\figure.pyc in get_tightbbox(self,renderer)
---> 1496 _bbox = Bbox.union([b for b in bb if b.width!=0 or b.height!=0])

C:\Python27\lib\site-packages\matplotlib\transforms.pyc in union(bboxes)
---> 714 assert(len(bboxes))

AssertionError:

Removing the bbox_inches='tight' argument seems to resolve the error and saves a file but there is no picture there, only a completely blank .png file.

I have made sure that our versions of python, matplotlib and other packages are all the same. Has anyone come across this before? I'm thinking it could be a bug in matplotlib, but then that would not make sense as it works fine on my computer and we have the same versions. Any ideas or suggestions?

Upvotes: 5

Views: 6336

Answers (4)

aseagram
aseagram

Reputation: 1231

In my own code I "resolved" this issue by calling savefig on the figure, rather than from pyplot (plt.savefig()), i.e.:

fig.savefig(filename, bbox_inches='tight')

where fig is an instance of matplotlib.figure.Figure. This was not an issue for me because of ipython, but rather it originated from trying to update and draw figures in a long loop.

Upvotes: 1

someguy
someguy

Reputation: 31

I had the very same error message. I showed the image via gui and then saved it, which yielded the error. I resolved it by first saving it and only thereafter showing it.

Upvotes: 3

Osmond Bishop
Osmond Bishop

Reputation: 8180

The error was produced when running ipython inline. 

ipython.exe notebook --pylab=inline

To fix this problem just remove the '=inline'.

Upvotes: 1

Hooked
Hooked

Reputation: 88118

This usually means no figures are rendered to the canvas. This also explains why, when you the argument is removed there is no corresponding image! For example:

import pylab
pylab.savefig('test', bbox_inches='tight')

Yields a similar error:

    pylab.savefig('test', bbox_inches='tight')
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 471, in savefig
    return fig.savefig(*args, **kwargs)
  File "/usr/lib/pymodules/python2.7/matplotlib/figure.py", line 1185, in savefig
    self.canvas.print_figure(*args, **kwargs)
  File "/usr/lib/pymodules/python2.7/matplotlib/backend_bases.py", line 1985, in print_figure
    bbox_inches = self.figure.get_tightbbox(renderer)
  File "/usr/lib/pymodules/python2.7/matplotlib/figure.py", line 1326, in get_tightbbox
    _bbox = Bbox.union([b for b in bb if b.width!=0 or b.height!=0])
  File "/usr/lib/pymodules/python2.7/matplotlib/transforms.py", line 675, in union
    assert(len(bboxes))

Upvotes: 4

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