title: Find Per group a specific value in another Column if does not exist in that group delete that group
body: <p>I am having a trouble in deleting some records from a dataframe. If i groupby a certain column and check for each this column group in another column that for each group does it have any specific value in another column if that specific value does not exist delete that whole group from first column (The column upon which we have applied group by earlier). My data look like this:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th><strong>search_value_per_group</strong></th>
  <th><strong>Column_to_Be_Grouped</strong></th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>Pakistan</td>
  <td>Ehsan</td>
  </tr>
  <tr>
  <td>Saudi Arab</td>
  <td>Irshad</td>
  </tr>
  <tr>
  <td>Pakistan</td>
  <td>Ayesha</td>
  </tr>
  <tr>
  <td>India</td>
  <td>Ehsan</td>
  </tr>
  <tr>
  <td>Switzerland</td>
  <td>Ehsan</td>
  </tr>
  <tr>
  <td>Nigeria</td>
  <td>Ehsan</td>
  </tr>
  <tr>
  <td>Saudi Arabia</td>
  <td>Ayesha</td>
  </tr>
  <tr>
  <td>UK</td>
  <td>Ayesha</td>
  </tr>
  <tr>
  <td>Pakistan</td>
  <td>Zohan</td>
  </tr>
  <tr>
  <td>Afghanistan</td>
  <td>Zohan</td>
  </tr>
  <tr>
  <td>Iraq</td>
  <td>Zohan</td>
  </tr>
  <tr>
  <td>Iran</td>
  <td>Zohan</td>
  </tr>
  <tr>
  <td>USA</td>
  <td>Zohan</td>
  </tr>
  <tr>
  <td>Netherland</td>
  <td>Irshad</td>
  </tr>
  <tr>
  <td>Switzerland</td>
  <td>Irshad</td>
  </tr>
  <tr>
  <td>India</td>
  <td>Irshad</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>I want to delete all that whole group which do not have <strong>Pakistan</strong> in that group. For example in my dataframe i will Delete All <strong>Irshad</strong> from  <strong>Column_to_Be_Grouped</strong> because in all irshad i do not have <strong>Pakistan</strong> and my desired output will look like this as follows:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th><strong>search_value_per_group</strong></th>
  <th><strong>Column_to_Be_Grouped</strong></th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>Pakistan</td>
  <td>Ehsan</td>
  </tr>
  <tr>
  <td>Pakistan</td>
  <td>Ayesha</td>
  </tr>
  <tr>
  <td>India</td>
  <td>Ehsan</td>
  </tr>
  <tr>
  <td>Switzerland</td>
  <td>Ehsan</td>
  </tr>
  <tr>
  <td>Nigeria</td>
  <td>Ehsan</td>
  </tr>
  <tr>
  <td>Saudi Arabia</td>
  <td>Ayesha</td>
  </tr>
  <tr>
  <td>UK</td>
  <td>Ayesha</td>
  </tr>
  <tr>
  <td>Pakistan</td>
  <td>Zohan</td>
  </tr>
  <tr>
  <td>Afghanistan</td>
  <td>Zohan</td>
  </tr>
  <tr>
  <td>Iraq</td>
  <td>Zohan</td>
  </tr>
  <tr>
  <td>Iran</td>
  <td>Zohan</td>
  </tr>
  <tr>
  <td>USA</td>
  <td>Zohan</td>
  </tr>
  </tbody>
  </table>
  </div>