title: Pandas: Ternary conditional operator for setting a value in a DataFrame
body: <p>I have a dataframe <code>pd</code>. I would like to change a value of column <code>irr</code> depending on whether it is above or below a thresh hold.</p>
  
  <p>How can  I do this in a single line? Now I have </p>
  
  <pre><code>pd['irr'] = pd['irr'][pd['cs']*0.63 &gt; pd['irr']] = 1.0
  pd['irr'] = pd['irr'][pd['cs']*0.63 &lt;=  pd['irr']] = 0.0
  </code></pre>
  
  <p>The problem of course is that I change <code>irr</code> and check it again in the next line.</p>
  
  <p>Is there something like a ternary conditional operator for pandas?</p>