CODEWITHSUNDEEP
pythonmatplotlibcron
bgame2498
bgame2498

Reputation: 4847

Running a python script with cron, matplotlib error

I am trying to run a python script using cron. The script runs without issue from the command line but has problems with matplotlib when run from cron. The error is below.

Traceback (most recent call last):

File "/home/ubuntu/python/spread.py", line 154, in <module>
    plot_spread(lat, lon, vals, mean, maxs, mins, stdp, stdm, ens_members)
  
File "/home/ubuntu/python/spread.py", line 81, in plot_spread
    plt.fill_between(x, maxs, stdp, color='r', alpha=0.2)
  
File "/usr/lib/python2.7/dist-packages/matplotlib-1.5.0_818.gfd83789-py2.7-linux-x86_64.egg/matplotlib/pyplot.py", line 2785, in fill_between
    ax = gca()
  
File "/usr/lib/python2.7/dist-packages/matplotlib-1.5.0_818.gfd83789-py2.7-linux-x86_64.egg/matplotlib/pyplot.py", line 928, in gca
    return gcf().gca(**kwargs)
  
File "/usr/lib/python2.7/dist-packages/matplotlib-1.5.0_818.gfd83789-py2.7-linux-x86_64.egg/matplotlib/pyplot.py", line 578, in gcf
    return figure()
  
File "/usr/lib/python2.7/dist-packages/matplotlib-1.5.0_818.gfd83789-py2.7-linux-x86_64.egg/matplotlib/pyplot.py", line 527, in figure
    **kwargs)
  
File "/usr/lib/python2.7/dist-packages/matplotlib-1.5.0_818.gfd83789-py2.7-linux-x86_64.egg/matplotlib/backends/backend_qt4agg.py", line 46, in new_figure_manager
    return new_figure_manager_given_figure(num, thisFig)
  
File "/usr/lib/python2.7/dist-packages/matplotlib-1.5.0_818.gfd83789-py2.7-linux-x86_64.egg/matplotlib/backends/backend_qt4agg.py", line 53, in new_figure_manager_given_figure
    canvas = FigureCanvasQTAgg(figure)
  
File "/usr/lib/python2.7/dist-packages/matplotlib-1.5.0_818.gfd83789-py2.7-linux-x86_64.egg/matplotlib/backends/backend_qt4agg.py", line 76, in __init__
    FigureCanvasQT.__init__(self, figure)
  
File "/usr/lib/python2.7/dist-packages/matplotlib-1.5.0_818.gfd83789-py2.7-linux-x86_64.egg/matplotlib/backends/backend_qt4.py", line 68, in __init__
    _create_qApp()
  
File "/usr/lib/python2.7/dist-packages/matplotlib-1.5.0_818.gfd83789-py2.7-linux-x86_64.egg/matplotlib/backends/backend_qt5.py", line 138, in _create_qApp
    raise RuntimeError('Invalid DISPLAY variable')

RuntimeError: Invalid DISPLAY variable

Upvotes: 3

Views: 1188

Answers (1)

Tamirlan
Tamirlan

Reputation: 392

I got a similar error when I tried to import matplotlib.pyplot in python using cron. You can force matplotlib to not use any Xwindows backend. Do this:

import matplotlib as mpl
mpl.use('Agg')
import matplotlib.pyplot as plt

These links might be also helpful:

Generating a PNG with matplotlib when DISPLAY is undefined

Generating matplotlib graphs without a running X server

Hope this is helpful!

Upvotes: 6

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