title: ValueError: Can only compare identically-labeled Series objects in 2.7
body: <p>I am attempting to compare a column in 2 different data frames and getting an error.  My goal is to determine if the playerID in df1 matches the playerID in df2. Also not sure if it makes a difference but the data in each data frame is of different lengths.</p>
  
  <p>Here is my code with examples of the data frames:</p>
  
  <pre><code>cleaned_hof_df = hof_df[(hof_df.inducted == 'Y') &amp; (hof_df.category == 'Player')] 
  cleaned_hof_df.reset_index(drop = True, inplace = True)
  
  cleaned_hof_df.head(3)
  
  cleaned_wins_losses_df = pitching_df[(pitching_df.W &gt; 0) &amp; (pitching_df.L &gt; 0)] 
  cleaned_wins_losses_df.reset_index(drop = True, inplace = True)
  
  cleaned_wins_losses_df.head(3)
  
  cleaned_hof_df.playerID == cleaned_wins_losses_df.playerID
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/0wvza.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0wvza.png" alt="Here is my code with examples of the data frames"></a></p>