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From Koobas <koo...@gmail.com>
Subject Re: Why some userId has no recommendations?
Date Thu, 13 Feb 2014 05:27:24 GMT
5 should get 107 as a recommendation, whether user-based or item-based.
No clue why you're not getting it.



On Wed, Feb 12, 2014 at 11:50 PM, 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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