title: Pandas: Accessing data with list of dates and DateTimeIndex
body: <p>I have a pandas DataFrame with a <code>DateTimeIndex</code>:</p>
  
  <pre><code>                           A          B
  2016-04-25 18:50:06   440.967796   201.049600  
  2016-04-25 18:50:13   441.054995   200.767034  
  2016-04-25 18:50:20   441.142337   200.484475
  ...
  2016-07-27 18:50:06   440.967796   201.049600  
  2016-07-27 18:50:13   441.054995   200.767034  
  2016-07-27 18:50:20   441.142337   200.484475
  </code></pre>
  
  <p>I would like to extract all the data of a given date <code>yyyy-mm-dd</code> using a list of dates: <code>['2016-04-25','2016-04-28',...]</code></p>
  
  <p>I tried the following:</p>
  
  <pre><code> df[df.index.isin(['2016-04-25', '2016-04-26'])]
  
   Empty DataFrame
  </code></pre>
  
  <p>I would like to retrieve all the data (data of the whole day) of the dates given in this list</p>