title: Pandas merge by name and date (multiple columns)
body: <p>I am looking to merge two data frames, first by name and then by date. </p>
  
  <p>df 1 looks like this </p>
  
  <pre><code>symbol. X.  X.  X.  X. date
  AA.                    2018-01-16
  AA.                    2018-05-04
  ....
  </code></pre>
  
  <p>then df2</p>
  
  <pre><code>symbol.  X.  X.  X. X. date
  AA.                   2018-01-03
  AA.                   2018-01-03
  </code></pre>
  
  <p>I have tried many variations of the following:</p>
  
  <pre><code>data = pd.merge(df1, df2, left_on = ['symbol', 'date'], how = 'left') 
  </code></pre>
  
  <p>All I want to do is a left join where the data comes out:</p>
  
  <pre><code>symbol.  X.  X. X. date
  AA.                2018-01-03
  AA.                2018-01-04
  ....
  </code></pre>
  
  <p>Any and all help would be greatly appreciated​, I cannot figure out what I am doing wrong here</p>