title: Pandas adding row at index 0
body: <p>I have a dataframe <code>df</code> with one row, like so:</p>
  <pre><code>               Player      Team  Points  Mean  Price  Value
  Round                                                              
  1              Salah  Liverpool     4.5    4.5   6.89  1.89
  </code></pre>
  <p>Now I need to add a dummy column at index 0 with an open price 'Price' = 5.0, obtained by <code>df['Price'] - df['Value']</code>, and all other column values set to <code>0.0</code>, ending up with, like so:</p>
  <pre><code>               Player      Team  Points  Mean  Price  Value
  Round
  0              Salah  Liverpool     0.0    0.0   5.0    0.0                        
  1              Salah  Liverpool     4.5    4.5   6.89  1.89
  </code></pre>
  <hr />
  <pre><code>atleta_data.loc[-1] = [df['Player'].item(), 
                         df['Team'].item(),
                         0.0, 
                         0.0, 
                         (df['Price'].item() - df['Value'].item()), 
                         0.0]  
  atleta_data.index = atleta_data.index +1  # shifting index
  atleta_data = atleta_data.sort_index()  # sorting by index
  </code></pre>
  <p>But I'm getting Rounds 0 and 2.</p>
  <pre><code>              Player      Team  Points  Mean  Price  Value
  Round
  0              Salah  Liverpool     0.0    0.0   5.0    0.0                        
  2              Salah  Liverpool     4.5    4.5   6.89  1.89
  </code></pre>
  <p>How can I end up with 0 and 1 for Rounds?</p>