title: How can I remove rows where frequency of the value is less than 5? Python, Pandas
body: <p>I have a dataframe with lots of rows.  Sometimes are values are one ofs and not very useful for my purpose.  </p>
  
  <p>How can I remove all the rows from where columns 2 and 3's value doesn't appear more than 5 times?</p>
  
  <p>df input</p>
  
  <pre><code> Col1     Col2     Col3       Col4
   1        apple    tomato     banana
   1        apple    potato     banana
   1        apple    tomato     banana
   1        apple    tomato     banana
   1        apple    tomato     banana
   1        apple    tomato     banana
   1        grape    tomato     banana
   1        pear     tomato     banana
   1        lemon    tomato     banana
  </code></pre>
  
  <p>output</p>
  
  <pre><code> Col1     Col2     Col3       Col4
   1        apple    tomato     banana
   1        apple    tomato     banana
   1        apple    tomato     banana
   1        apple    tomato     banana
   1        apple    tomato     banana
  </code></pre>