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From Koobas <koo...@gmail.com>
Subject Re: Why some userId has no recommendations?
Date Thu, 13 Feb 2014 13:21:28 GMT
User 3 gave a recommendation to item 107.
User 5 did not rate 107.


On Thu, Feb 13, 2014 at 1:57 AM, Suresh M <suresh4master@gmail.com> wrote:

> user 5 has given rating for all 5 books,
> So there will be no recommendations for him.
>
>
>
> On 12 February 2014 08:55, jiangwen jiang <jiangwen127@gmail.com> wrote:
>
> > Hi, all:
> >
> > I try to user mahout api to make recommendations, but I find some userId
> > has no recommendations, why?
> >
> > here is my code
> > public static void main(String args[]) throws Exception {
> >         String inFile = "F:\\hadoop\\data\\recsysinput.txt";
> >         DataModel dataModel = new FileDataModel(new File(inFile));
> >         UserSimilarity userSimilarity = new
> > PearsonCorrelationSimilarity(dataModel);
> >         UserNeighborhood userNeighborhood = new
> > NearestNUserNeighborhood(100, userSimilarity, dataModel);
> >         Recommender recommender = new
> > GenericUserBasedRecommender(dataModel, userNeighborhood, userSimilarity);
> >
> >         for (int i = 1; i < 5; i++) {
> >             List<RecommendedItem> recommendations =
> > recommender.recommend(i, 1);
> >
> >             System.out.println("recommend for user:" + i);
> >             for (RecommendedItem recommendation : recommendations) {
> >                 System.out.println(recommendation);
> >             }
> >         }
> >     }
> >
> >
> > input data(recsysinput.txt):
> > 1,101,5.0
> > 1,102,3.0
> > 1,103,2.5
> > 2,101,2
> > 2,102,2.5
> > 2,103,5
> > 2,104,2
> > 3,101,2.5
> > 3,104,4
> > 3,105,4.5
> > 3,107,5
> > 4,101,5
> > 4,103,3
> > 4,104,4.5
> > 4,106,4
> > 5,101,4
> > 5,102,3
> > 5,103,2
> > 5,104,4
> > 5,105,3.5
> > 5,106,4
> >
> > output:
> > recommend for user:1
> > RecommendedItem[item:104, value:5.0]
> > recommend for user:2
> > RecommendedItem[item:106, value:4.0]
> > recommend for user:3
> > RecommendedItem[item:106, value:4.0]
> > recommend for user:4
> > RecommendedItem[item:105, value:5.0]
> > recommend for user:5
> >
> > UserId 5 has no recommendations, is it right?
> > Can I get some recommendations for userId 5, even if the recommendation
> > results are not good enough?
> >
> > thanks
> > Regards!
> >
>

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