Matplotlib seems to require the $DISPLAY environment variable which means a running X server.
Some web hosting services do not allow a running X server session.
Is there a way to generate graphs using matplotlib without a running X server?
[username@hostname ~]$ python2.6 Python 2.6.5 (r265:79063, Nov 23 2010, 02:02:03) [GCC 4.1.2 20080704 (Red Hat 4.1.2-48)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import matplotlib.pyplot as plt >>> fig = plt.figure() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/home/username/lib/python2.6/matplotlib-1.0.1-py2.6-linux-i686.egg/matplotlib/pyplot.py", line 270, in figure **kwargs) File "/home/username/lib/python2.6/matplotlib-1.0.1-py2.6-linux-i686.egg/matplotlib/backends/backend_tkagg.py", line 80, in new_figure_manager window = Tk.Tk() File "/usr/local/lib/python2.6/lib-tk/Tkinter.py", line 1643, in __init__ self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use) _tkinter.TclError: no display name and no $DISPLAY environment variable >>>
@Neil's answer is one (perfectly valid!) way of doing it, but you can also simply call
matplotlib.use('Agg') before importing
matplotlib.pyplot, and then continue as normal.
import matplotlib as mpl mpl.use('Agg') import matplotlib.pyplot as plt fig = plt.figure() ax = fig.add_subplot(111) ax.plot(range(10)) fig.savefig('temp.png')
You don't have to use the Agg backend, as well. The pdf, ps, svg, agg, cairo, and gdk backends can all be used without an X-server. However, only the Agg backend will be built by default (I think?), so there's a good chance that the other backends may not be enabled on your particular install.
Alternately, you can just set the backend parameter in your
.matplotlibrc file to automatically have
matplotlib.pyplot use the given renderer.
You need to use the matplotlib API directly rather than going through the pylab interface. There's a good example here: