title: Pandas Dataframe Aggregation
body: <p>I have the following dataframe (I didnt include an index here, but obvisouly there is also an index)</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>ID_1</th>
  <th>ID_2</th>
  <th>Count</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>55</td>
  <td>62</td>
  <td>1000</td>
  </tr>
  <tr>
  <td>62</td>
  <td>55</td>
  <td>1200</td>
  </tr>
  <tr>
  <td>...</td>
  <td>...</td>
  <td>...</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>Now I would like to aggregate those two columns, since I do not care if the ID is in the column ID_1 or in ID_2.</p>
  <p>I would like to get the following result:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>ID_1</th>
  <th>ID_2</th>
  <th>Count</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>55</td>
  <td>62</td>
  <td>2200</td>
  </tr>
  <tr>
  <td>62</td>
  <td>55</td>
  <td>2200</td>
  </tr>
  <tr>
  <td>...</td>
  <td>...</td>
  <td>...</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>That means that I want to sum the Count column over all the rows in my dataframe where two IDs are the same (doesnt care if they are in ID_1 column or ID_2 column).</p>
  <p>I thought about grouping the dataframe, but that did not work properly.</p>
  <p>I am happy for any help!</p>