title: Find min index over all Panda data frame
body: <p> Hi </p>
  
  <p>I want to find minimum index overall data frame.Actually, my columns are not features and I just use their labels.</p>
  
  <p>assume my data frame is something like this :</p>
  
  <pre><code>     0    1    2
  a  100    1    2
  b    1  100    4
  c    2    4  100
  </code></pre>
  
  <p>I want a function which returns <code>('b' , '0')</code> or <code>('a','1')</code></p>
  
  <p>I would appreciate for your solutions.</p>