You can also find similar items using neural networks. There was an awesome talk about that at pycon 2009 : http://us.pycon.org/2009/conference/schedule/event/7

You can also find similar items using neural networks. There was an awesome talk about that at pycon 2009 : http://us.pycon.org/2009/conference/schedule/event/71/ http://us.pycon.org/2009/conference/schedule/event/71/ Neural network data mining can also sometimes survive missing data or extrapolate from unknown instances.