Python 当 DISPLAY 未定义时使用 Matplotlib
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Using Matplotlib when DISPLAY is undefined
提问by Chris Fonnesbeck
When using Matplotlib on a remote machine (e.g. on Travis CI), I run into frequent runtime errors related to the DISPLAY environmental variable not being set. As recommended, I have set the Aggbackend via matplotlib.useat the beginning of my test scripts, and have ensured there are no calls to show(). Nevertheless, I still get errors such the following:
在远程机器上（例如在 Travis CI 上）使用 Matplotlib 时，我经常遇到与未设置 DISPLAY 环境变量相关的运行时错误。按照建议，我在测试脚本的开头设置了Agg后端 via matplotlib.use，并确保没有调用show(). 尽管如此，我仍然收到如下错误：
Traceback (most recent call last):
File "/home/travis/anaconda/envs/testenv/lib/python2.7/site-packages/nose/case.py", line 197, in runTest
self.test(*self.arg)
File "/home/travis/build/pymc-devs/pymc/pymc/tests/test_plots.py", line 36, in test_multichain_plots
forestplot(ptrace, vars=['early_mean', 'late_mean'])
File "/home/travis/build/pymc-devs/pymc/pymc/plots.py", line 325, in forestplot
interval_plot = subplot(gs[0])
File "/home/travis/anaconda/envs/testenv/lib/python2.7/site-packages/matplotlib/pyplot.py", line 896, in subplot
fig = gcf()
File "/home/travis/anaconda/envs/testenv/lib/python2.7/site-packages/matplotlib/pyplot.py", line 450, in gcf
return figure()
File "/home/travis/anaconda/envs/testenv/lib/python2.7/site-packages/matplotlib/pyplot.py", line 423, in figure
**kwargs)
File "/home/travis/anaconda/envs/testenv/lib/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py", line 31, in new_figure_manager
return new_figure_manager_given_figure(num, thisFig)
File "/home/travis/anaconda/envs/testenv/lib/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py", line 38, in new_figure_manager_given_figure
canvas = FigureCanvasQTAgg(figure)
File "/home/travis/anaconda/envs/testenv/lib/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py", line 70, in __init__
FigureCanvasQT.__init__( self, figure )
File "/home/travis/anaconda/envs/testenv/lib/python2.7/site-packages/matplotlib/backends/backend_qt4.py", line 207, in __init__
_create_qApp()
File "/home/travis/anaconda/envs/testenv/lib/python2.7/site-packages/matplotlib/backends/backend_qt4.py", line 62, in _create_qApp
raise RuntimeError('Invalid DISPLAY variable')
RuntimeError: Invalid DISPLAY variable
Are there other recommendations to averting this?
还有其他建议可以避免这种情况吗？
回答by ariddell
Using xvfbworks, see Travis's GUI & Headless browser testingdocumentation.
使用xvfb作品，请参阅 Travis 的GUI 和 Headless 浏览器测试文档。
p.s. The matplotlib.use('Agg')trick works for me.
ps这个matplotlib.use('Agg')技巧对我有用。
