frommatplotlibimportpyplotaspltplt.plot([1,2], [1,2])

---------------------------------------------------------------------------TclError                                  Traceback (most recent call last)<ipython-input-2-8dd816f9ddc7> in <module>()----> 1 plt.plot([1, 2], [1, 2])/home/goldbaum/.virtualenvs/yt-dev/local/lib/python2.7/site-packages/matplotlib/pyplot.pyc in plot(*args, **kwargs)   3145 @_autogen_docstring(Axes.plot)   3146 def plot(*args, **kwargs):-> 3147     ax = gca()   3148     # allow callers to override the hold state by passing hold=True|False   3149     washold = ax.ishold()/home/goldbaum/.virtualenvs/yt-dev/local/lib/python2.7/site-packages/matplotlib/pyplot.pyc in gca(**kwargs)    926     matplotlib.figure.Figure.gca : The figure's gca method.    927     """--> 928     return gcf().gca(**kwargs)    929    930 # More ways of creating axes:/home/goldbaum/.virtualenvs/yt-dev/local/lib/python2.7/site-packages/matplotlib/pyplot.pyc in gcf()    576         return figManager.canvas.figure    577     else:--> 578         return figure()    579    580/home/goldbaum/.virtualenvs/yt-dev/local/lib/python2.7/site-packages/matplotlib/pyplot.pyc in figure(num, figsize, dpi, facecolor, edgecolor, frameon, FigureClass, **kwargs)    525                                         frameon=frameon,    526                                         FigureClass=FigureClass,--> 527                                         **kwargs)    528    529         if figLabel:/home/goldbaum/.virtualenvs/yt-dev/local/lib/python2.7/site-packages/matplotlib/backends/backend_tkagg.pyc in new_figure_manager(num, *args, **kwargs)     82     FigureClass = kwargs.pop('FigureClass', Figure)     83     figure = FigureClass(*args, **kwargs)---> 84     return new_figure_manager_given_figure(num, figure)     85     86/home/goldbaum/.virtualenvs/yt-dev/local/lib/python2.7/site-packages/matplotlib/backends/backend_tkagg.pyc in new_figure_manager_given_figure(num, figure)     90     """     91     _focus = windowing.FocusManager()---> 92     window = Tk.Tk()     93     window.withdraw()     94/usr/lib/python2.7/lib-tk/Tkinter.pyc in __init__(self, screenName, baseName, className, useTk, sync, use)   1765                 baseName = baseName + ext   1766         interactive = 0-> 1767         self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)   1768         if useTk:   1769             self._loadtk()TclError: no display name and no $DISPLAY environment variable