title: Replace the column value with a particular string
body: <p>I have this Dataframe: I want to replace the 1 with df.rule1 and 2 with df.rule2</p>
  
  <pre><code>+---+---------+------+
  |SNo|Operation|Points|
  +---+---------+------+
  |  1|    1 &amp; 2|   100|
  |  2|    1 | 2|   200|
  |  3|1 | 2 &amp; 3|   350|
  +---+---------+------+
  
  </code></pre>
  
  <p>I want this dataframe into this:</p>
  
  <pre><code>+---+------------------------------+------+
  |SNo|Operation                     |Points|
  +---+------------------------------+------+
  |1  |df.rule1 &amp; df.rule2           |100   |
  |2  |df.rule1 | df.rule2           |200   |
  |3  |df.rule1 | df.rule2 &amp; df.rule3|350   |
  +---+------------------------------+------+
  </code></pre>