Extra reading  
If you have enjoyed this small introduction to taxicab geometry, and would like to know more about this subject and/or about computational geometry and pattern recognition in general, this is a short list of references. I highly recommend the taxicab geometry page from GVSU and the book by Krause. (And of course the projects of my fellow students!)
Computational geometry and pattern recognition are widely documented on the web, but I think these are a good place to start.