title: Calculating the slope between each value and time step - pandas
body: <p>First off, here is my data:</p>
  
  <pre><code>    val slopes  time
  0   11  0.0     1
  1   11  0.0     2
  2   11  0.0     3
  3   06  0.0     4
  4   05  0.0     5
  </code></pre>
  
  <p>For each timestep, i'd like to calculate the differences between the values.</p>