title: take standard deviation of datetime in python
body: <p>I am importing the datetime library in my python program and am taking the duration of multiple events. Below is my code for that:</p>
  
  <pre><code>d1 = datetime.datetime.strptime(starttime, '%Y-%m-%d:%H:%M:%S')
  d2 = datetime.datetime.strptime(endtime, '%Y-%m-%d:%H:%M:%S')
  duration = d2 - d1
  print str(duration)
  </code></pre>
  
  <p>Now I have a value in the variable "duration". The output of this will be:</p>
  
  <pre><code>0:00:15
  0:00:15
  0:00:15
  0:00:15
  0:00:15
  0:00:05
  0:00:05
  0:00:05
  0:00:05
  0:00:05
  0:00:10
  0:00:10
  0:00:10
  0:00:10
  0:45:22
  </code></pre>
  
  <p>I want to take the standard deviation of all the durations and determine if there is an anomaly. For example, the 00:45:22 is an anomaly and I want to detect that. I could do this if I knew what format datetime was in, but it doesn't appear to be digits or anything..I was thinking about splitting the values up from : and using all the values in between, but there might be a better way.</p>
  
  <p>Ideas?</p>