title: How to put text outside python plots and change its rotation?
body: <p>I am creating a 20 x 20 figure using plt.subplots. All my plots have the same axis label therefore instead of writing the label on each subplot I would like to add one label as text by defining the position of this text in figure coordinates instead of data coordinates.</p>
  
  <p>From another question I figured how to do this:</p>
  
  <p><code>plt.gcf().text(0.02, 0.5, textstr, fontsize=14)</code></p>
  
  <p>However, I could not figure out how to change the rotation of this text so it is parallel to the y axis and looking like a general y axis label.</p>