The best way to fix _tkinter.tclerror: no display name and no $display environment variable error

Question

I get an 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

when I try to run the following code:

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)

How to fix _tkinter.tclerror: no display name and no $display environment variable. Please give me some good ideas.

Juliette Mary · Accepted Answer

It was a problem I was having with Colab. The following code lines helped me to solve it. It should be at the top of your notebook.

### CREATE VIRTUAL DISPLAY ###
!apt-get install -y xvfb # Install X Virtual Frame Buffer
import os
os.system('Xvfb :1 -screen 0 1600x1200x16 &') # create virtual display with size 1600x1200 and 16 bit color. Color can be changed to 24 or 8
os.environ['DISPLAY']=':1.0' # tell X clients to use our virtual DISPLAY :1.0.

%matplotlib inline

### INSTALL GHOSTSCRIPT (Required to display NLTK trees) ###
!apt install ghostscript python3-tk

Anna · Answer

Matplotlib defaults to the Xwindows Backend. Matplotlib must be set to disable the Xwindows Backend This code should be added to the beginning of your script ( prior to importing Pyplot).

import matplotlib
matplotlib.use('Agg')

To use non-interactive backend, add .config/matplotlib/matplotlibrc line HTML12

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

Oder, connect to server using ssh -X remoteMachine command. To use Xwindows You can also export display export DISPLAY=mymachine.com:0.0

Lou Guichard · Answer

This is the final answer. It works in 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

It wasn't my intention to have it use the Agg' backend. I wanted it to only be used when it would go through Travis CI, for example.

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The best way to fix _tkinter.tclerror: no display name and no $display environment variable error