_tkinter.TclError：没有显示名称，也没有$ DISPLAY环境变量

Question

我在服务器中运行一个简单的python脚本：import matplotlib.pyplot as pltimport numpy as npx = np.random.randn(60)y = np.random.randn(60)plt.scatter(x, y, s=20)out_png = 'path/to/store/out_file.png'plt.savefig(out_png, dpi=150)我尝试python example.py在已安装matplotlib 1.5.1的服务器中使用该命令，但失败并显示以下错误：Traceback (most recent call last):  File "example.py", line 7, in <module>    plt.scatter(x, y, s=20)  File "/home/USER/.virtualenvs/nnet/lib/python2.7/site-packages/matplotlib/pyplot.py", line 3241, in scatter    ax = gca()  File "/home/USER/.virtualenvs/nnet/lib/python2.7/site-packages/matplotlib/pyplot.py", line 928, in gca    return gcf().gca(**kwargs)  File "/home/USER/.virtualenvs/nnet/lib/python2.7/site-packages/matplotlib/pyplot.py", line 578, in gcf    return figure()  File "/home/USER/.virtualenvs/nnet/lib/python2.7/site-packages/matplotlib/pyplot.py", line 527, in figure**kwargs)  File "/home/USER/.virtualenvs/nnet/lib/python2.7/site-packages/matplotlib/backends/backend_tkagg.py", line 84, in new_figure_manager    return new_figure_manager_given_figure(num, figure)  File "/home/USER/.virtualenvs/nnet/lib/python2.7/site-packages/matplotlib/backends/backend_tkagg.py", line 92, in new_figure_manager_given_figure    window = Tk.Tk()  File "/usr/local/lib/python2.7/lib-tk/Tkinter.py", line 1810, in __init__    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)_tkinter.TclError: no display name and no $DISPLAY environment variable这是怎么回事

Answer 1

您可以通过在.py脚本的非常开头添加这两行来解决此问题。

import matplotlib

matplotlib.use('Agg')

PS：如果在源代码的开头没有添加这两行，则错误仍然存在。

Answer 2

为了加总答案，我在所需脚本的开头使用了它。因此它可以在不同的环境下平稳运行。

import os

import matplotlib as mpl

if os.environ.get('DISPLAY','') == '':

    print('no display found. Using non-interactive Agg backend')

    mpl.use('Agg')

import matplotlib.pyplot as plt

因为我不希望它总是使用'Agg'后端，所以仅当它通过Travis CI时才使用。