title: TypeError: strptime() argument 1 must be str, not float
body: <p>I'm having parsing errors on my code, below is the code and almost understandable dataset</p>
  
  <pre><code>import numpy as np
  import pandas as pd
  from datetime import datetime as dt
  
  data0 = pd.read_csv('2009-10.csv')
  data1 = pd.read_csv('2010-11.csv')
  
  def parse_date(date):
      if date == '':
          return None
      else:
          return dt.strptime(date, '%d/%m/%y').date()
  
  data0.Date = data0.Date.apply(parse_date)
  data1.Date = data1.Date.apply(parse_date)
  </code></pre>
  
  <p><strong><em>TypeError: strptime() argument 1 must be str, not float</em></strong></p>
  
  <pre><code>Date    HomeTeam    AwayTeam    FTHG    FTAG    FTR HTHG    HTAG    HTR Referee HS  AS  HST AST HF  AF  HC  AC  HY  AY  HR  AR  B365H   B365D   B365A
  15/08/09    Aston Villa Wigan   0   2   A   0   1   A   M Clattenburg   11  14  5   7   15  14  4   6   2   2   0   0   1.67    3.6 5.5
  15/08/09    Blackburn   Man City    0   2   A   0   1   A   M Dean  17  8   9   5   12  9   5   4   2   1   0   0   3.6 3.25    2.1
  15/08/09    Bolton  Sunderland  0   1   A   0   1   A   A Marriner  11  20  3   13  16  10  4   7   2   1   0   0   2.25    3.25    3.25
  15/08/09    Chelsea Hull    2   1   H   1   1   D   A Wiley 26  7   12  3   13  15  12  4   1   2   0   0   1.17    6.5 21
  15/08/09    Everton Arsenal 1   6   A   0   3   A   M Halsey    8   15  5   9   11  13  4   9   0   0   0   0   3.2 3.25    2.3
  
  Date    HomeTeam    AwayTeam    FTHG    FTAG    FTR HTHG    HTAG    HTR Referee HS  AS  HST AST HF  AF  HC  AC  HY  AY  HR  AR  B365H   B365D   B365A
  14/08/10    Aston Villa West Ham    3   0   H   2   0   H   M Dean  23  12  11  2   15  15  16  7   1   2   0   0   2   3.3 4
  14/08/10    Blackburn   Everton 1   0   H   1   0   H   P Dowd  7   17  2   12  19  14  1   3   2   1   0   0   2.88    3.25    2.5
  14/08/10    Bolton  Fulham  0   0   D   0   0   D   S Attwell   13  12  9   7   12  13  4   8   1   3   0   0   2.2 3.3 3.4
  14/08/10    Chelsea West Brom   6   0   H   2   0   H   M Clattenburg   18  10  13  4   10  10  3   1   1   0   0   0   1.17    7   17
  14/08/10    Sunderland  Birmingham  2   2   D   1   0   H   A Taylor    6   13  2   7   13  10  3   6   3   3   1   0   2.1 3.3 3.6
  14/08/10    Tottenham   Man City    0   0   D   0   0   D   A Marriner  22  11  18  7   13  16  10  3   0   2   0   0   2.4 3.3 3
  </code></pre>