title: Transferring values between two columns in a pandas data frame
body: <p>I have a pandas data frame like this:</p>
  <pre><code>p q
  0.5 0.5
  0.6 0.4
  0.3 0.7
  0.4 0.6
  0.9 0.1
  </code></pre>
  <p>So, I want to know, how can I transfer greater values to p column and vice versa for q column (Transfering smaller values to q column) like this:</p>
  <pre><code>p q
  0.5 0.5
  0.6 0.4
  0.7 0.3
  0.6 0.4
  0.9 0.1
  </code></pre>