title: Adjust figure size with respect to the axes size?
body: <p>Let's say I create a simple plot with matplotlib </p>
  
  <pre><code>import matplotlib.pyplot as plt
  fig = plt.figure()
  ax = fig.add_subplot(111)
  
  plot stuff etc .. . 
  </code></pre>
  
  <p>After I finished the plotting routines I want to adjust the size of my figure (but keeping all aspect ratios the same), such that the total height of <code>ax</code> is set to a constant value i.e. 3 inches.
  Is there a nice and short way to archieve this ? </p>
  
  <p>EDIT: I know how to change the figure size, but here i want to adjust it according to the size of the axes.</p>