Generating a PNG with matplotlib when DISPLAY is undefined

Question

I am trying to use networkx with Python  When I run this program it get this error  Is there anything missing      usr bin env python  import networkx as nx import matplotlib import matplotlib pyplot import matplotlib pyplot as plt  G nx Graph   G add node 1  G add nodes from  2 3 4 5 6 7 8 9 10    nx draw graphviz G   nx write dot G   node png   nx draw G  plt savefig   var www node png     Traceback  most recent call last     File  graph py   line 13  in  lt module gt      nx draw G    File   usr lib pymodules python2 5 networkx drawing nx pylab py   line 124  in draw     cf pylab gcf     File   usr lib pymodules python2 5 matplotlib pyplot py   line 276  in gcf     return figure     File   usr lib pymodules python2 5 matplotlib pyplot py   line 254  in figure       kwargs    File   usr lib pymodules python2 5 matplotlib backends backend tkagg py   line 90  in new figure manager     window   Tk Tk     File   usr lib python2 5 lib-tk Tkinter py   line 1650  in   init       self tk    tkinter create screenName  baseName  className  interactive  wantobjects  useTk  sync  use   tkinter TclError  no display name and no  DISPLAY environment variable     I get a different error now      usr bin env python  import networkx as nx import matplotlib import matplotlib pyplot import matplotlib pyplot as plt  matplotlib use  Agg    G nx Graph   G add node 1  G add nodes from  2 3 4 5 6 7 8 9 10    nx draw graphviz G   nx write dot G   node png   nx draw G  plt savefig   var www node png        usr lib pymodules python2 5 matplotlib   init   py 835  UserWarning   This call to matplotlib use   has no effect because the the backend has already been chosen  matplotlib use   must be called  before  pylab  matplotlib pyplot  or matplotlib backends is imported for the first time     if warn  warnings warn  use error msg  Traceback  most recent call last     File  graph py   line 15  in  lt module gt      nx draw G    File   usr lib python2 5 site-packages networkx-1 2 dev-py2 5 egg networkx drawing nx pylab py   line 124  in draw     cf pylab gcf     File   usr lib pymodules python2 5 matplotlib pyplot py   line 276  in gcf     return figure     File   usr lib pymodules python2 5 matplotlib pyplot py   line 254  in figure       kwargs    File   usr lib pymodules python2 5 matplotlib backends backend tkagg py   line 90  in new figure manager     window   Tk Tk     File   usr lib python2 5 lib-tk Tkinter py   line 1650  in   init       self tk    tkinter create screenName  baseName  className  interactive  wantobjects  useTk  sync  use   tkinter TclError  no display name and no  DISPLAY environment variable     I get a different error now      usr bin env python  import networkx as nx import matplotlib import matplotlib pyplot import matplotlib pyplot as plt  matplotlib use  Agg    G nx Graph   G add node 1  G add nodes from  2 3 4 5 6 7 8 9 10    nx draw graphviz G   nx write dot G   node png   nx draw G  plt savefig   var www node png        usr lib pymodules python2 5 matplotlib   init   py 835  UserWarning   This call to matplotlib use   has no effect because the the backend has already been chosen  matplotlib use   must be called  before  pylab  matplotlib pyplot  or matplotlib backends is imported for the first time     if warn  warnings warn  use error msg  Traceback  most recent call last     File  graph py   line 15  in  lt module gt      nx draw G    File   usr lib python2 5 site-packages networkx-1 2 dev-py2 5 egg networkx drawing nx pylab py   line 124  in draw     cf pylab gcf     File   usr lib pymodules python2 5 matplotlib pyplot py   line 276  in gcf     return figure     File   usr lib pymodules python2 5 matplotlib pyplot py   line 254  in figure       kwargs    File   usr lib pymodules python2 5 matplotlib backends backend tkagg py   line 90  in new figure manager     window   Tk Tk     File   usr lib python2 5 lib-tk Tkinter py   line 1650  in   init       self tk    tkinter create screenName  baseName  className  interactive  wantobjects  useTk  sync  use   tkinter TclError  no display name and no  DISPLAY environment variable

User · Answer

import matplotlib matplotlib use  Agg   import matplotlib pyplot as plt   It works for me

User · Answer

When signing into the server to execute the code use this instead   ssh -X username servername   the -X will get rid of the no display name and no  DISPLAY environment variable error

User · Answer

The main problem is that  on your system  matplotlib chooses an x-using backend by default  I just had the same problem on one of my servers   The solution for me was to add the following code in a place that gets read before any other pylab matplotlib pyplot import   import matplotlib   Force matplotlib to not use any Xwindows backend  matplotlib use  Agg     The alternative is to set it in your  matplotlibrc

User · Answer

I got the error while using matplotlib through Spark  matplotlib use  Agg   doesn t work for me  In the end  the following code works for me  More here  import matplotlib pyplot as plt  plt switch backend  agg

User · Answer

I will just repeat what  Ivo Bosticky said which can be overlooked  Put these lines at the VERY start of the py file   import matplotlib matplotlib use  Agg      Or one would get error      usr lib pymodules python2 7 matplotlib   init   py 923  UserWarning   This call to   matplotlib use   has no effect because the the backend has already been chosen  matplotlib use   must be called  before  pylab  matplotlib pyplot     This will resolve all Display issue

User · Answer

What system are you on  It looks like you have a system with X11  but the DISPLAY environment variable was not properly set  Try executing the following command and then rerunning your program   export DISPLAY localhost 0

User · Answer

To make sure your code is portable across Windows  Linux and OSX and for systems with and without displays  I would suggest following snippet   import matplotlib import os   must be before importing matplotlib pyplot or pylab  if os name     posix  and  DISPLAY  not in os environ      matplotlib use  Agg      now import other things from matplotlib import matplotlib pyplot as plt   Credit  https   stackoverflow com a 45756291 207661

User · Answer

The clean answer is to take a little bit of time correctly prepare your execution environment   The first technique you have to prepare your execution environment is to use a matplotlibrc file  as wisely recommended by Chris Q   setting  backend   Agg   in that file  You can even control     with no code changes     how and where matplotlib looks for and finds the matplotlibrc file   The second technique you have to prepare your execution environment is to use the MPLBACKEND environment variable  and inform your users to make use of it    export MPLBACKEND  agg  python  lt program using matplotlib py gt    This is handy because you don t even have to provide another file on disk to make this work  I have employed this approach with  for example  testing in continuous integration  and running on remote machines that do not have displays   Hard-coding your matplotlib backend to  Agg  in your Python code is like bashing a square peg into a round hole with a big hammer  when  instead  you could have just told matplotlib it needs to be a square hole

User · Answer

One other thing to check is whether your current user is authorised to connect to the X display  In my case  root was not allowed to do that and matplotlib was complaining with the same error   user debian    xauth list          debian unix 10  MIT-MAGIC-COOKIE-1  ae921efd0026c6fc9d62a8963acdcca0 root debian    xauth add debian unix 10  MIT-MAGIC-COOKIE-1 ae921efd0026c6fc9d62a8963acdcca0 root debian    xterm   source  http   www debian-administration org articles 494 https   debian-administration org article 494 Getting X11 forwarding through ssh working after running su

User · Answer

I found this snippet to work well when switching between X and no-X 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

User · Answer

Just as a complement of Reinout s answer   The permanent way to solve this kind of problem is to edit  matplotlibrc file  Find it via      import matplotlib    matplotlib matplotlib fname     This is the file location in Ubuntu   etc matplotlibrc    Then modify the backend in that file to backend   Agg  That is it

User · Answer

For Google Cloud Machine Learning Engine   import matplotlib as mpl mpl use  Agg   from matplotlib backends backend pdf import PdfPages   And then to print to file    PDF build and save     def multi page filename  figs None  dpi 200           pp   PdfPages filename          if figs is None              figs    mpl pyplot figure n  for n in mpl pyplot get fignums            for fig in figs              fig savefig pp  format  pdf   bbox inches  tight   fig size  10  8           pp close     and to create the PDF   multi page report name

[python] Generating a PNG with matplotlib when DISPLAY is undefined

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