title: Attempting to split every value in a Pandas Dataframe gives an error
body: <p>I have a df:</p>
  <pre><code>  A                B
  0 hello there      123
  1 general kenobi   456
  </code></pre>
  <p>I want to split column A on the space so I end up with</p>
  <pre><code>  A                B
  0 hello            123
  1 general          456
  </code></pre>
  <p>df['A'] = df['A'].str.split('i')</p>
  <p>gives back</p>
  <pre><code>  A                B
  0 [hello, there]      123
  1 [general, kenobi]   456
  </code></pre>
  <p>but when I try and get the correct index df['A'] = df['A'].str.split(' ')[0]</p>
  <blockquote>
  <p>I get ValueError: Length of values does not match length of index</p>
  </blockquote>