title: Problems with values within a key in pandas
body: <p>I'm having issues figuring out how to obtain a delta within the content of individual values, while using pandas:</p>
  <p>Here's an example of my dataframe:  (I also don't know how to convert all the numbers that are held as strings to numbers).</p>
  <p><code>df =  pd.DataFrame({'ID': ['ID1','ID2', 'ID3'], 'SEQ': ['10 20', '20 25', '1 10 45 50' ]}) </code></p>
  <pre><code>0 ID1 10 20
  1 ID2 20 25
  2 ID3 1 10 45 50
  </code></pre>
  <p>And I want to obtain another column that has the values of the 2nd number minus the 1st value (ignoring the 1!) for every set of values from 'SEQ'. So, it would look like this:</p>
  <p><code>'Delta': [10,5,35]</code> (Those are the results of (20 - 10),(25 -20), and so on)</p>
  <p>The final df would look like this:</p>
  <pre><code>  ID   SEQ          DELTA
  0 ID1  10 20        10
  1 ID2  40 45        5
  2 ID3  1 10 45 50   35 
   
  </code></pre>