title: DataFrame has no attribute to str problem
body: <p><a href="https://i.stack.imgur.com/85JzJ.png" rel="nofollow noreferrer">Here is my csv file in case you need it</a> </p>
  
  <p>I am trying to run through every MLB team's playoff appearances and record them, however <code>"DataFrame" has not attribute to "str"</code> keeps popping up. Here is my code:</p>
  
  <pre><code>record_dict = {}
  file=open("playoff_teams.csv", mode="r")
  for line in file.readlines():
      split_line = line.split()
      record_dict[split_line[0]]=split_line[1:]
  df_playoffs = pd.DataFrame.from_dict(record_dict, orient='index' )
  
  list(sorted(set(df_pitching.team))) == list(sorted(set(df_batting.team))) == list(sorted(set(df_playoffs.index)))
  
  df_all = df_pitching.merge(df_batting, on=['year','team'], 
  how='left', suffixes=('_pitching', '_batting'))
  
  playoff_appearance = []
  for i in range(1969, 2019):                                                                      
      df = df_all[df_all.year == i]
  
      for team in df.team:
          df_plyoff = df_playoffs[df_playoffs.index == team]
  
          if df_plyoff.str.contains(str(i))[0]:
              playoff_appearance.append(1)   
          else:
              playoff_appearance.append(0)
  
  world_series = []
  for i in range(1969, 2019):
      df = df_all[df_all.year == i]
  
      for team in df.team:
          df_ws = df_playoffs[df_playoffs.index == team]
  
          if df_ws.world_series.str.contains(str(i))[0]:  
              world_series.append(1)  
          else:
              world_series.append(0)
  </code></pre>
  
  <p>Here is my error message:</p>
  
  <pre><code>Traceback (most recent call last):
    File "/Users/hannahbeegle/Desktop/Baseball.py", line 148, in &lt;module&gt;
      if df_plyoff.str.contains(str(i))[0]:
    File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pandas/core/generic.py", line 5067, in __getattr__
      return object.__getattribute__(self, name)
  AttributeError: 'DataFrame' object has no attribute 'str'
  </code></pre>