_tkinter.TclError:没有显示名称并且没有$ DISPLAY环境变量

问题:_tkinter.TclError:没有显示名称并且没有$ DISPLAY环境变量

我在服务器中运行一个简单的python脚本:

import matplotlib.pyplot as plt
import numpy as np

x = 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

I am running a simple python script in the server:

import matplotlib.pyplot as plt
import numpy as np

x = 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)

I try to use the command python example.py in this server which has matplotlib 1.5.1 installed it fails with the error:

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

What is happening here?


回答 0

Matplotlib默认情况下选择Xwindows后端。您需要将matplotlib设置为不使用Xwindows后端。

将此代码添加到脚本的开头(在导入pyplot之前),然后重试:

import matplotlib
matplotlib.use('Agg')

或添加到.config/matplotlib/matplotlibrcbackend: Agg以使用非交互式后端。

echo "backend: Agg" > ~/.config/matplotlib/matplotlibrc

或者在连接到服务器时使用ssh -X remoteMachine命令来使用Xwindows。

您也可以尝试导出显示:export DISPLAY=mymachine.com:0.0

有关更多信息:https : //matplotlib.org/faq/howto_faq.html#matplotlib-in-a-web-application-server

Matplotlib chooses Xwindows backend by default. You need to set matplotlib to not use the Xwindows backend.

Add this code to the start of your script (before importing pyplot) and try again:

import matplotlib
matplotlib.use('Agg')

Or add to .config/matplotlib/matplotlibrc line backend: Agg to use non-interactive backend.

echo "backend: Agg" > ~/.config/matplotlib/matplotlibrc

Or when connect to server use ssh -X remoteMachine command to use Xwindows.

Also you may try to export display: export DISPLAY=mymachine.com:0.0.

For more info: https://matplotlib.org/faq/howto_faq.html#matplotlib-in-a-web-application-server


回答 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。

You can solve it by adding these two lines in the VERY beginning of your .py script.

import matplotlib
matplotlib.use('Agg')

PS: The error will still exists if these two lines are not added in the very beginning of the source code.


回答 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时才如此。

To add up on the answer, I used this at the beginning of the needed script. So it runs smoothly on different environments.

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

Because I didn’t want it to be alsways using the 'Agg' backend, only when it would go through Travis CI for example.


回答 3

我在尝试在Raspberry Pi上远程运行一个简单的tkinter应用程序时遇到了同样的问题。就我而言,我确实希望在pi显示器上显示tkinter GUI,但是我希望能够从主机通过SSH执行它。我也没有使用matplotlib,所以这不是造成我问题的原因。我可以通过将DISPLAY环境变量设置为错误来解决该问题,该错误表明了以下命令:

export DISPLAY=:0.0

可以在此处找到有关显示环境变量的功能以及语法为何如此奇怪的很好的解释:https : //askubuntu.com/questions/432255/what-is-display-environment-variable

I had this same issue trying to run a simple tkinter app remotely on a Raspberry Pi. In my case I did want to display the tkinter GUI on the pi display, but I want to be able to execute it over SSH from my host machine. I was also not using matplotlib, so that wasn’t the cause of my issue. I was able to resolve the issue by setting the DISPLAY environment variable as the error suggests with the command:

export DISPLAY=:0.0

A good explanation of what the display environment variable is doing and why the syntax is so odd can be found here: https://askubuntu.com/questions/432255/what-is-display-environment-variable


回答 4

另一个解决方案是安装Xvfb,然后将显示导出到该文件。即:

disp=:8
screen=0
geom=640x480x24
exec Xvfb $disp -screen $screen $geom 2>/tmp/Xvfb.log &

然后

$ export DISPLAY =:8

$ ./example.py

Another solution is to install Xvfb, and export your display to it. ie:

disp=:8
screen=0
geom=640x480x24
exec Xvfb $disp -screen $screen $geom 2>/tmp/Xvfb.log &

Then

$ export DISPLAY=:8

$ ./example.py


回答 5

在使用Xshell连接Linux服务器时,我也遇到了这个问题。

在寻找方法之后,我找到了Xming + Xshell来解决matplotlib的图像显示问题。

如果上述解决方案不能解决您的问题,请尝试在使用Xshell的条件下下载Xming。然后在Xshell中设置属性,SSH->隧道-> X11transfer->选择X DISPLAY localhost:0.0

I also met this problem while using Xshell to connect Linux server.

After seaching for methods, I find Xming + Xshell to solve image imshow problem with matplotlib.

If solutions aboved can’t solve your problem, just try to download Xming under the condition you’re using Xshell. Then set the attribute in Xshell, SSH->tunnel->X11transfer->choose X DISPLAY localhost:0.0


回答 6

为了查看图像,图解以及远程计算机的Windows上显示的所有内容,您需要像这样连接到它:

ssh -X user@hostname

这样,您就可以访问X服务器。X服务器是X窗口系统中的程序,可在本地计算机(即用户直接使用的计算机)上运行,并处理对这些计算机上的图形卡,显示屏和输入设备(通常是键盘和鼠标)的所有访问。

更多信息在这里

In order to see images, plots and anything displayed on windows on your remote machine you need to connect to it like this:

ssh -X user@hostname

That way you enable the access to the X server. The X server is a program in the X Window System that runs on local machines (i.e., the computers used directly by users) and handles all access to the graphics cards, display screens and input devices (typically a keyboard and mouse) on those computers.

More info here.