title: How to get the sum of a value out of transactions over time
body: <p>I have a df showing aprox. 1.600.000 transactions like:</p>
  <pre><code>start           duration    avg         stop
  1.457423e+09    1821.0      0.951126    1.457425e+09
  1.457389e+09    35577.0     0.517104    1.457424e+09
  1.457425e+09    1232.0      0.000000    1.457425e+09
  1.457425e+09    333.0       1.100000    1.457425e+09
  1.457425e+09    1.0         0.000000    1.457425e+09
  </code></pre>
  <p>Transaction can be overlapping. How can I I get the aggregated sum over time as shown in the lower graph in the picture using Python/Matplotlib</p>
  <p><a href="https://i.stack.imgur.com/psmaB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/psmaB.png" alt="enter image description here" /></a></p>