title: Pandas split column into multiple columns by comma
body: <p>I am trying to split a column into multiple columns based on comma/space separation.</p>
  
  <p>My dataframe currently looks like</p>
  
  <pre><code>     KEYS                                                  1
  0   FIT-4270                                          4000.0439
  1   FIT-4269                                          4000.0420, 4000.0471
  2   FIT-4268                                          4000.0419
  3   FIT-4266                                          4000.0499
  4   FIT-4265                                          4000.0490, 4000.0499, 4000.0500, 4000.0504,
  </code></pre>
  
  <p>I would like</p>
  
  <pre><code>   KEYS                                                  1           2            3        4 
  0   FIT-4270                                          4000.0439
  1   FIT-4269                                          4000.0420  4000.0471
  2   FIT-4268                                          4000.0419
  3   FIT-4266                                          4000.0499
  4   FIT-4265                                          4000.0490  4000.0499  4000.0500  4000.0504 
  </code></pre>
  
  <p>My code currently removes The KEYS column and I'm not sure why. Could anyone improve or help fix the issue?</p>
  
  <pre><code>v = dfcleancsv[1]
  
  #splits the columns by spaces into new columns but removes KEYS?
  
  dfcleancsv = dfcleancsv[1].str.split(' ').apply(Series, 1)
  </code></pre>