title: List rows which column value is not unique in dataframe
body: <p>I have a dataframe where some of the SongIds are repeated. I would like to extract those rows which have the repetition. Any idea how? Tried:</p>
  
  <pre><code>dfB[dfB.SongId.duplicated()]
  </code></pre>
  
  <p>But didn't work well.</p>
  
  <p>This is an example of my dataframe. SongId 0, 10 and 16 are repeated in this example:</p>
  
  <p><a href="https://i.stack.imgur.com/RE4MU.png" rel="noreferrer"><img src="https://i.stack.imgur.com/RE4MU.png" alt="enter image description here"></a></p>