On Fri, Sep 20, 2002 at 08:46:27AM +0100, Simon Wistow wrote:
> For reasons best left to my own imagination I'm looking to do something
> that will show an average rating for a object based on all submitted
> ratings but also do a "if you liked this then you'd also like ...".
>
> So, anybody got any smart ideas on how to do it. I wondered about Markov
> Chains but they have a concept of order as far as I know. Am I
> overengineering? Is there some really simple way of doing this?
My psuedo-SQL is very rusty, but given a reasonable DBMS one can
surely do somthing like this:
Get the average score for this item:
select arithmetic_mean(score) from rating
where item = $current_item
People who liked this also liked:
select item from rating
where score > $hi_score_threshold
and user in (select user from rating
where score > $hi_score_threshold
and item = $current_item)
