title: Comparing two data sets and find out common names
body: <p>How can i compare two datasets and find the common gene names, provided if CNA and chr of both datasets are same</p>
  
  <p>dt1</p>
  
  <pre><code>    CNA     chr   Genes
      gain    5     Sall3,Kcng2,Atp9b,Nfatc1,Ctdp1
      loss    5     RNU6-866P,TRIM5,TRIM34,TRIM22,TRIM5
      gain    2     PDIA5,SEMA5B
  </code></pre>
  
  <p>dt2 </p>
  
  <pre><code>    CNA     chr   Genes
      gain    5     Sall3,Nfatc1,SNORA5,SNORA5
      gain    5     RNU6-866P,OR8J1,OR8K3,OR8K3
      gain    2     PDIA5,DCC
  </code></pre>
  
  <p>expected output</p>
  
  <p>df3  </p>
  
  <pre><code>    CNA     chr   Genes
      gain    5     Sall3,Nfatc1
      gain    2     PDIA5
  </code></pre>
  
  <p>Im sure this is trivial question, but would love to have suggestions to help me a bit.</p>