title: histogram matplotlib, text out of histogram
body: <p>with python and matplotlib, I can plot a histogram and I can put a text in the histogram area, </p>
  
  <pre><code>import matplotlib.pyplot as plt
  import numpy as np
  
  
  a = np.array([10, 10, 10, 8, 9, 9, 7])
  
  mean = np.mean(a)
  
  fig = plt.figure(figsize=(14, 8))
  ax = fig.add_subplot(111)
  
  plt.hist(a, alpha=0.2)
  
  ax.set_ylabel(u'Frequency')
  ax.set_xlabel(u'Some data')
  ax.xaxis.set_label_coords(0.8, -0.1)
  
  ax.text(mean, 0, '$\mu$\n{}'.format(mean))
  
  plt.show()
  </code></pre>
  
  <p>how I can put the text under the axis?</p>
  
  <p><a href="https://i.stack.imgur.com/5PwEr.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/5PwEr.jpg" alt="histogram"></a>
  </p>