当 DISPLAY 未定义时使用 Matplotlib [英] Using Matplotlib when DISPLAY is undefined

问题描述

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环境变量有关的运行时错误.按照建议，我在测试脚本的开头通过 matplotlib.use 设置了 Agg 后端，并确保没有调用 show().尽管如此，我仍然收到如下错误:

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 Agg backend via matplotlib.use at the beginning of my test scripts, and have ensured there are no calls to show(). Nevertheless, I still get errors such the following:

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

还有其他建议可以避免这种情况吗?

Are there other recommendations to averting this?

推荐答案

Using xvfb 工作，见 Travis 的

Using xvfb works, see Travis's GUI & Headless browser testing documentation.

p.s. matplotlib.use('Agg')技巧对我有用.

p.s. The matplotlib.use('Agg') trick works for me.

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