title: dtypes. Difference between S1 and S2 in Python
body: <p>I have two arrays of strings:</p>
  
  <pre><code>In [51]: r['Z']
  Out[51]: 
  array(['0', '0', '0', ..., '0', '0', '0'], 
        dtype='|S1')
  
  In [52]: r['Y']                                                                                                                
  Out[52]: 
  array(['X0', 'X0', 'X0', ..., 'X0', 'X1', 'X1'], 
        dtype='|S2')
  </code></pre>
  
  <p>What is the difference between S1 and S2? Is it just that they hold entries of different length? </p>
  
  <p>What if my arrays have strings of <strong>different lengths</strong>?</p>
  
  <p>Where can I find a list of all possible dtypes and what they mean?</p>