title: Clustering a list of dates
body: <p>I have a list of dates I'd like to cluster into 3 clusters.  Now, I can see hints that I should be looking at k-means, but all the examples I've found so far are related to coordinates, in other words, pairs of list items.</p>
  
  <p>I want to take this list of dates and append them to three separate lists indicating whether they were before, during or after a certain event.  I don't have the time for this event, but that's why I'm guessing it by breaking the date/times into three groups.</p>
  
  <p>Can anyone please help with a simple example on how to use something like numpy or scipy to do this?</p>