title: Python: how to make two lists from a dictionary
body: <p>I have a dictionary.</p>
  
  <pre><code>{1 : [1.2, 2.3, 4.9, 2.0],  2 : [4.1, 5.1, 6.3],  3 : [4.9, 6.8, 9.5, 1.1, 7.1]}
  </code></pre>
  
  <p>I want to pass each key:value pair to an instance of <code>matplotlib.pyplot</code> as two lists: x values and y values.</p>
  
  <p>Each key is an x value associated with each item in its value.</p>
  
  <p>So I want two lists for each key:</p>
  
  <pre><code>[1,1,1,1] [1.2,2.3,4.9,2.0]
  
  [2,2,2] [4.1,5.1,6.3]
  
  [3,3,3,3,3] [4.9,6.8,9.5,1.1,7.1]
  </code></pre>
  
  <p>Is there an elegant way to do this?</p>
  
  <p>Or perhaps there is a way to pass a dict to <code>matplotlib.pyplot</code>?</p>