title: How to remove duplicate values in specific column without removing related row
body: <p>Want to remove duplicate values in specific column without deleting the rows related with duplicate column values as below example:</p>
  
  <pre><code>Input
  -----
      Date    Market      Quantity
  4/2/2018    Indonesia   1000
  4/2/2018    Australia   500
  4/2/2018    India       300
  4/2/2018    USA         500
  4/2/2018    Germany     200
  5/2/2018    India       400
  5/2/2018    Japan       400
  5/2/2018    Russia      457
  6/2/2018    Austria     260
  6/2/2018    Swiss       700
  6/2/2018    USA         1200
  6/2/2018    Indonesia   400
  
  
  output
  ------
      Date    Market      Quantity
  4/2/2018    Indonesia   1000
              Australia   500
              India       300
              USA         500
              Germany     200
  5/2/2018    India       400
              Japan       400
              Russia      457
  6/2/2018    Austria     260
              Swiss       700
              USA         1200
              Indonesia   400
  </code></pre>
  
  <p>And if possible , how to plot a graph(bar/column) for same output(something like given)?
  <a href="https://i.stack.imgur.com/dBnuH.png" rel="nofollow noreferrer">Sample Graph</a></p>