matplotlib compilation and running issues

jmssnyder · September 17, 2015, 6:04pm

To who it may concern,

I installed matplotlib on my computer and tried to run a program with the
code below:

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 10)
line, = plt.plot(x, np.sin(x), '--', linewidth=2)

When I ran the program I could the below error output:

[vrsops at am-linux-212 cpcharts]$ python line_demo_dash_control.py
Traceback (most recent call last):
  File "line_demo_dash_control.py", line 12, in <module>
    line, = plt.plot(x, np.sin(x), '--', linewidth=2)
  File "/usr/lib64/python2.7/site-packages/matplotlib/pyplot.py", line
3092, in plot
    ax = gca()
  File "/usr/lib64/python2.7/site-packages/matplotlib/pyplot.py", line 828,
in gca
    ax = gcf().gca(**kwargs)
  File "/usr/lib64/python2.7/site-packages/matplotlib/pyplot.py", line 462,
in gcf
    return figure()
  File "/usr/lib64/python2.7/site-packages/matplotlib/pyplot.py", line 435,
in figure
    **kwargs)
  File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py",
line 47, in new_figure_manager
    return new_figure_manager_given_figure(num, thisFig)
  File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py",
line 54, in new_figure_manager_given_figure
    canvas = FigureCanvasQTAgg(figure)
  File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py",
line 72, in __init__
    FigureCanvasQT.__init__(self, figure)
  File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt4.py",
line 68, in __init__
    _create_qApp()
  File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt5.py",
line 138, in _create_qApp
    raise RuntimeError('Invalid DISPLAY variable')
RuntimeError: Invalid DISPLAY variable

What is causing these errors and how do I resolve this issue? Also echo
$DISPLAY is blank.

Thank you for your time.

-Jason
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efiring · September 17, 2015, 6:17pm

To who it may concern,

I installed matplotlib on my computer and tried to run a program with
the code below:

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 10)
line, = plt.plot(x, np.sin(x), '--', linewidth=2)

When I ran the program I could the below error output:

[vrsops at am-linux-212 cpcharts]$ python line_demo_dash_control.py
Traceback (most recent call last):
   File "line_demo_dash_control.py", line 12, in <module>
     line, = plt.plot(x, np.sin(x), '--', linewidth=2)
   File "/usr/lib64/python2.7/site-packages/matplotlib/pyplot.py", line
3092, in plot
     ax = gca()
   File "/usr/lib64/python2.7/site-packages/matplotlib/pyplot.py", line
828, in gca
     ax = gcf().gca(**kwargs)
   File "/usr/lib64/python2.7/site-packages/matplotlib/pyplot.py", line
462, in gcf
     return figure()
   File "/usr/lib64/python2.7/site-packages/matplotlib/pyplot.py", line
435, in figure
     **kwargs)
   File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py",
line 47, in new_figure_manager
     return new_figure_manager_given_figure(num, thisFig)
   File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py",
line 54, in new_figure_manager_given_figure
     canvas = FigureCanvasQTAgg(figure)
   File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py",
line 72, in __init__
     FigureCanvasQT.__init__(self, figure)
   File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt4.py",
line 68, in __init__
     _create_qApp()
   File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt5.py",
line 138, in _create_qApp
     raise RuntimeError('Invalid DISPLAY variable')
RuntimeError: Invalid DISPLAY variable

What is causing these errors and how do I resolve this issue? Also echo
$DISPLAY is blank.

Are you in a graphical environment, or are you using ssh to connect to
the machine? Lack of a DISPLAY variable suggests the latter--no X.

Eric

···

On 2015/09/17 8:04 AM, Jason Snyder wrote:

Thank you for your time.

-Jason

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Matplotlib-users at python.org
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jblackburne · September 17, 2015, 6:20pm

Hi Jason,

$DISPLAY should normally look like HOSTNAME:X where HOSTNAME is your local
machine's hostname and X is some number. That's assuming you have a
graphical display running. Matplotlib is trying to start up one of its
interactive backends, but cannot because your $DISPLAY is blank. You can
fix this by setting $DISPLAY to its proper value, or by switching backends
to a non-interactive backend like 'agg', which will let you save figures to
disk.

I can't help you with the former, except to say that if you are connecting
to a remote machine using ssh, you can try forwarding your local display to
the remote machine using ssh -X.

To do the latter, insert these 2 lines before your code:
import matplotlib as mpl
mpl.use('agg')

-Jeff

···

On Thu, Sep 17, 2015 at 11:04 AM, Jason Snyder <jmssnyder at ucdavis.edu> wrote:

To who it may concern,

I installed matplotlib on my computer and tried to run a program with the
code below:

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 10)
line, = plt.plot(x, np.sin(x), '--', linewidth=2)

When I ran the program I could the below error output:

[vrsops at am-linux-212 cpcharts]$ python line_demo_dash_control.py
Traceback (most recent call last):
  File "line_demo_dash_control.py", line 12, in <module>
    line, = plt.plot(x, np.sin(x), '--', linewidth=2)
  File "/usr/lib64/python2.7/site-packages/matplotlib/pyplot.py", line
3092, in plot
    ax = gca()
  File "/usr/lib64/python2.7/site-packages/matplotlib/pyplot.py", line
828, in gca
    ax = gcf().gca(**kwargs)
  File "/usr/lib64/python2.7/site-packages/matplotlib/pyplot.py", line
462, in gcf
    return figure()
  File "/usr/lib64/python2.7/site-packages/matplotlib/pyplot.py", line
435, in figure
    **kwargs)
  File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py",
line 47, in new_figure_manager
    return new_figure_manager_given_figure(num, thisFig)
  File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py",
line 54, in new_figure_manager_given_figure
    canvas = FigureCanvasQTAgg(figure)
  File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py",
line 72, in __init__
    FigureCanvasQT.__init__(self, figure)
  File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt4.py",
line 68, in __init__
    _create_qApp()
  File
"/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_qt5.py",
line 138, in _create_qApp
    raise RuntimeError('Invalid DISPLAY variable')
RuntimeError: Invalid DISPLAY variable

What is causing these errors and how do I resolve this issue? Also echo
$DISPLAY is blank.

Thank you for your time.

-Jason

_______________________________________________
Matplotlib-users mailing list
Matplotlib-users at python.org
Matplotlib-users Info Page

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