title: Pandas join rows as new columns
body: <p>I have the following df:</p>
  <pre><code>import pandas as pd
  df = pd.DataFrame({'C':[5,4],'P':[2.3,5.6]})
  </code></pre>
  <p><a href="https://i.stack.imgur.com/vFyBm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vFyBm.png" alt="enter image description here" /></a></p>
  <p>I would like to join row 1 to row 0 as follows:</p>
  <p><a href="https://i.stack.imgur.com/Eff1S.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Eff1S.png" alt="enter image description here" /></a></p>
  <p>I understand that duplicate columns get assigned a &quot;_1&quot;.</p>