Re: [Matplotlib-users] RuntimeError: CGContextRef is NULL

[Nicolas R. <Nic...@lo...>]

Thanks. Unfortunately wx and tk backends are broken on my machine (but they may be easier to fix).
I will file a bug report for the native backend bug. 

Nicolas


On Oct 4, 2010, at 22:27 , Friedrich Romstedt wrote:

> 2010/10/4 Nicolas Rougier <Nic...@lo...>:
>> I'm trying to have animated plots using draw_artist on mac os x and I got an error with the following script:
>> 
>> import numpy as np
>> import matplotlib.pyplot as plt
>> 
>> plt.ion()
>> plt.figure()
>> subplot = plt.subplot(1,1,1)
>> axis = plt.imshow(np.random.random((10,10)))
>> plt.draw()
>> subplot.draw_artist(axis)
>> plt.show()
>> 
>> The traceback is:
>> 
>> Traceback (most recent call last):
>>  File "matplotlib-bug.py", line 8, in <module>
>>    subplot.draw_artist(axis)
>>  File "/Volumes/Data/Local/lib/python2.7/site-packages/matplotlib/axes.py", line 1946, in draw_artist
>>    a.draw(self._cachedRenderer)
>>  File "/Volumes/Data/Local/lib/python2.7/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
>>    draw(artist, renderer, *args, **kwargs)
>>  File "/Volumes/Data/Local/lib/python2.7/site-packages/matplotlib/image.py", line 338, in draw
>>    gc = renderer.new_gc()
>>  File "/Volumes/Data/Local/lib/python2.7/site-packages/matplotlib/backends/backend_macosx.py", line 105, in new_gc
>>    self.gc.save()
>> RuntimeError: CGContextRef is NULL
>> 
>> 
>> Is there something wrong in my script (it seems to be working on linux) ?
> 
> I don't know what it is, and it looks like some problem with the
> Mac-native backend, but I believe you can sort it out by just
> switching the backend to e.g. TkAgg.
> 
> Friedrich