title: Split a large pandas dataframe
body: <p>I have a large dataframe with 423244 lines. I want to split this in to 4. I tried the following code which gave an error? <code>ValueError: array split does not result in an equal division</code></p>
  
  <pre><code>for item in np.split(df, 4):
      print item
  </code></pre>
  
  <p>How to split this dataframe in to 4 groups?</p>