title: accessing dictionary key and value with one key in a tuple
body: <p>I have a dictionary with tuples as key and a value like this:</p>
  
  <pre><code>dic = {('1/1/2016', '00:00'): data1,
         ('1/1/2016', '00:05'): data2,
         ('2/1/2016', '00:00'): data3}
  </code></pre>
  
  <p>I would like to access all the keys and values with only providing the first element of tuple (the date) without looping on all the data in dictionary. Is there any way to do that without too much processing? </p>