title: Pandas Merge/Join
body: <p>I have a dataframe called <code>Bob</code> with Columns = [A,B] and A has only unique values like a serial ID. Shape is (100,2)</p>
  
  <p>I have another dataframe called <code>Anna</code> with Columns [C,D,E,F] where C has the same values as A in bob but there are duplicates. Column D is a category (phone/laptop/ipad) that is defined by the serial ID found in C. Shape of <code>Anna</code> is (500,4).</p>
  
  <p>Example of row in anna:</p>
  
  <pre><code>A B C D
  K103 phone 12 17
  K103 phone 14 23
  G221 laptop 25 6
  </code></pre>
  
  <p>I want to create a new dataframe that has columns A,B,D by searching for value of A in anna[C]. The final dataframe should be shape (100,3)</p>
  
  <p>I'm finding this difficult with <code>pd.merge</code> (i tried left/inner/right joins) because it keeps creating 2 rows in the new dataframe with same values i.e. K103 will show up 2x in the new dataframe.</p>