title: How to check whether particular column completely match or not
body: <p>I would like to compare particular column with the other one.
  For instance,when I compare A column with B by using some method,
  it should return False.</p>
  
  <pre><code>    A   B
  0   1   2
  1   2   2
  2   3   3
  3   4   4
  </code></pre>
  
  <p>when I try</p>
  
  <pre><code>df.A==df.B
  </code></pre>
  
  <p>But this returns whether each elements match with the other.</p>
  
  <p>How can I compare column with the other one ?</p>