title: ValueError: Can only compare identically-labeled Series objects in pandas?
body: <p>[Sample Code]</p>
  <pre><code>d = {
     'country': ['IN', 'USA', 'USA', 'IN'],
     'username': ['abi.g', 'pugal.g', 'jan.g', 'jacob.h'],
     'email': ['abi@gmail.com', 'pugal.g@yahoo.in', 'jan232@gmail.com', 'jacob@hoi.com'],
     'ClusterID': ['', '4', '5', '9']
  }
  df1 = pd.DataFrame(d)
  
  data = [
     ['USA', 3490.89, 'qcx_taskid85_duns250437449', '3'], 
     ['JA', 1211, 'Pugal Gandi', '4'], 
     ['USA', 3455.00, 'Janani Khannan', '6']
  ]
  df2 = pd.DataFrame(data, columns=['country', 'salary', 'name', 'ClusterID'])
  
  df1.reset_index(inplace=True, drop=True)
  df2.reset_index(inplace=True, drop=True)
  df1.loc[df1['ClusterID'] == df2['ClusterID']]
  </code></pre>
  <p><a href="https://i.stack.imgur.com/9y5yM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9y5yM.png" alt="enter image description here" /></a>
  <a href="https://i.stack.imgur.com/zmNX1.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/zmNX1.png" alt="enter image description here" /></a></p>
  <p><strong>Qns:</strong> How to compare/filter the two columns using .loc, while the <strong>no. of records are different</strong> in pandas?</p>
  <p>Thanks,</p>