title: Plot occurrences over time in R or MATLAB from a dataset of the date of each occurrence
body: <p>I have a dataset where one column is a date of occurrence for each entry. I'd like to plot the occurrences of various subsets of this dataset over time. (See the sample data if this description is unclear.)</p>
  
  <p>This differs from the case where one has a column of time periods, such as years, and another of number of occurrences within that year. I need a way to group the dates, in the way occurrences in a range are grouped into bins to make a histogram, so that I can obtain frequency over a corresponding time interval that I can plot.</p>
  
  <p>I'm on the verge of writing python code to calculate these frequencies for arbitrary intervals semi-manually, but that would add a step to the process that I would have to repeat for each subset of the dataset.</p>
  
  <p>Is there a package or an inbuilt function in R or MATLAB that does this already? If so, how would I go about using it to do this?</p>
  
  <hr>
  
  <p>Below is some sample data, if my earlier description was unclear:</p>
  
  <pre><code>Category,Date  
  V,07/01/1993
  Y,05/18/2004
  X,12/20/2000
  X,02/19/2002
  X,02/19/2002
  X,02/19/2002
  V,04/14/2002
  V,12/20/2000
  V,12/20/2000
  V,01/08/2002
  Y,07/18/2006
  V,12/20/2000
  V,12/20/2000
  Y,04/20/2006
  X,11/12/2009
  X,04/03/2014
  </code></pre>
  
  <p>My desire is to plot number of occurrences of category V over time, such that it can be compared to Y over time and etc.</p>