title: Time differentiation in Pandas
body: <p>Say I have a dataframe with several timestamps and values. I would like to measure <code>Δ values / Δt</code>  every <code>2.5</code> seconds.  Does Pandas provide any utilities for time differentiation? </p>
  
  <pre><code>                              time_stamp   values
  19492   2014-10-06 17:59:40.016000-04:00  1832128                                
  167106  2014-10-06 17:59:41.771000-04:00  2671048                                
  202511  2014-10-06 17:59:43.001000-04:00  2019434                                
  161457  2014-10-06 17:59:44.792000-04:00  1294051                                
  203944  2014-10-06 17:59:48.741000-04:00   867856
  </code></pre>