title: Pandas Dataframe check if a value exists using regex
body: <p>I have a big dataframe and I want to check if any cell contains <code>admin</code> string. </p>
  
  <pre><code>   col1                   col2 ... coln
  0   323           roster_admin ... rota_user
  1   542  assignment_rule_admin ... application_admin
  2   123           contact_user ... configuration_manager
  3   235         admin_incident ... incident_user
  ... ...  ...                   ... ...
  </code></pre>
  
  <p>I tried to use <code>df.isin(['*admin*']).any()</code> but it seems like <code>isin</code> doesn't support regex. How can I search though all columns using regex? </p>
  
  <p>I have avoided using loops because the dataframe contains over 10 million rows and many columns and the efficiency is important for me.</p>