title: applying regex to a pandas dataframe
body: <p>I'm having trouble applying a regex function a column in a python dataframe.  Here is the head of my dataframe:</p>
  
  <pre><code>               Name   Season          School   G    MP  FGA  3P  3PA    3P%
   74       Joe Dumars  1982-83   McNeese State  29   NaN  487   5    8  0.625   
   84      Sam Vincent  1982-83  Michigan State  30  1066  401   5   11  0.455   
   176  Gerald Wilkins  1982-83     Chattanooga  30   820  350   0    2  0.000   
   177  Gerald Wilkins  1983-84     Chattanooga  23   737  297   3   10  0.300   
   243    Delaney Rudd  1982-83     Wake Forest  32  1004  324  13   29  0.448  
  </code></pre>
  
  <p>I thought I had a pretty good grasp of applying functions to Dataframes, so maybe my Regex skills are lacking.</p>
  
  <p>Here is what I put together:</p>
  
  <pre><code>import re
  
  def split_it(year):
      return re.findall('(\d\d\d\d)', year)
  
   df['Season2'] = df['Season'].apply(split_it(x))
  
  TypeError: expected string or buffer
  </code></pre>
  
  <p>Output would be a column called Season2 that contains the year before the hyphen.  I'm sure theres an easier way to do it without regex, but more importantly, i'm trying to figure out what I did wrong</p>
  
  <p>Thanks for any help in advance.</p>