title: Histogram in Python Using matplotlib
body: <p>I am struggling with this really badly. There is something that I'm just not getting. I have a function, which I want to plot a histogram of a dictionary with the keys on the x-axis and the values on the y-axis, then save the file in a location specified when calling the function. What I have is:</p>
  
  <pre><code>​import matplotlib.pyplot as plt
  
  
  def test(filename):
      dictionary = {0:1000, 1:20, 2:15, 3:0, 4:5}
      xmax = max(dictionary.keys())
      ymax = max(dictionary.values())
      plt.hist(dictionary,xmax)
      plt.title('Histogram Title')
      plt.xlabel('Label')
      plt.ylabel('Another Label')
      plt.axis([0, xmax, 0, ymax])
      plt.figure()
      plt.savefig(filename)
  
  test('test_graph.svg')
  </code></pre>
  
  <p>I simply cannot get this to work, and I've struggled for a very long time reading other questions and documentation. Any help would be greatly appreciated. Thanks.</p>
  
  <p>EDIT:</p>
  
  <p>The error I have is:</p>
  
  <pre><code>File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 343, in figure
      **kwargs)
    File "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line 80, in new_figure_manager
      window = Tk.Tk()
    File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1688, in __init__
      self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
  TclError: no display name and no $DISPLAY environment variable
  </code></pre>