title: How to get only the mismatched columns in pandas
body: <p>while comparing two csv files, I want to export the only columns which has mismatch.Below code gives me all the columns, not the mismatch column, in this case only email, profession column has
  the mismatch values between 2 dataframes. How to export only mismatch columns?</p>
  <pre><code>import pandas as pa
  df1 = pa.read_csv('data1.csv')
  df2 = pa.read_csv('data2.csv')
  diff =df1.merge(df2,indicator=True,how='outer')
  diff1 = diff[diff['_merge'] == 'left_only']
  print(diff1)
  </code></pre>
  <p>Below is the output</p>
  <pre><code>    id firstname lastname  ...                     email2      profession     _merge
  1  101  Gilligan    Brenn  ...   Gilligan.Brenn@gmail.com          worker  left_only
  8  108   Sherrie   Ventre  ...   Sherrie.Ventre@gmail.com  police officer  left_only
  9  109  Roseline   Roscoe  ...  Roseline.Roscoe@gmail.com       developer  left_only
  </code></pre>