title: how to make factor level selectinput filed in shiny dashboard
body: <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>sample</th>
  <th>type</th>
  <th>gender</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>sample1</td>
  <td>group1</td>
  <td>Male</td>
  </tr>
  <tr>
  <td>sample2</td>
  <td>group1</td>
  <td>Female</td>
  </tr>
  <tr>
  <td>sample3</td>
  <td>group1</td>
  <td>Male</td>
  </tr>
  <tr>
  <td>sample4</td>
  <td>group2</td>
  <td>Female</td>
  </tr>
  <tr>
  <td>sample5</td>
  <td>group2</td>
  <td>Female</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>Suppose user have uploaded above csv file and data stored  as reactive object -  metadata() .
  how can we create three selectinput fileds variable ,  condition1 and condition2 in dashboard,</p>
  <p>such that varible filed show type and gender.</p>
  <p>condition1  and condition2 fields show ; group1 and group2  (means all the levels of type) ; if user selects variable as type.</p>
  <p>similarly condition1  and condition2 fields show ; Male and Female  (means all the levels of gender) ; if user selects variable as gender.</p>
  <p>please help</p>