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From Sean Owen <sro...@gmail.com>
Subject Re: Clarifying output from Taste demo
Date Wed, 18 Mar 2009 17:51:28 GMT
Yeah that's basically right. It lists the user's top ratings first,
recommendations second. Recommendations are based on all ratings in the
model though, in theory.

Yes the example uses slope one internally. I like this algorithm best as a
general default. It is easy to tweak the example to use something else. It
is just another algorithm - works differently from the canonical recommender
sketched in the documentation and no doubt gives different results.

On Mar 18, 2009 5:42 PM, "Grant Ingersoll" <gsingers@apache.org> wrote:

Just to clarify, when I run the group lens demo, say with:
http://localhost:8080/mahout-taste-webapp/RecommenderServlet?userID=12&debug=true

I get something like:
User:User[id:12]
Recommender:
GroupLensRecommender[recommender:CachingRecommender[recommender:SlopeOneRecommender[weighted:true,
stdDevWeighted:true, diffStorage:MemoryDiffStorage]]]

Top 20 Preferences:
5.0     111     Taxi Driver (1976)      Drama|Thriller
5.0     1198    Raiders of the Lost Ark (1981)  Action|Adventure
5.0     1221    Godfather: Part II The (1974)   Action|Crime|Drama
5.0     2804    Christmas Story A (1983)        Comedy|Drama
...

Recommendations:
7.0     557     Mamma Roma (1962)       Drama
5.5     2510    Just the Ticket (1999)  Comedy|Romance
5.5     3295    Raining Stones (1993)   Drama
...

Thus, what I am seeing here, is the preferences are the movies that user 12
rated and which were then used to derive the recommendations listed at the
bottom, right?

Also, it says I'm using a SlopeOneRecommender, what does that do compared to
the other recommenders, as discussed in
http://localhost:8888/taste.html#examples?  That is, is it appropriate to
substitute in the other ones for this demo?  Would it be worth updating the
demo to show the results of the various recommenders?

Thanks
Grant

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