I guess you would get a 107 as a recommendation for 5 if you switched to user-based?
On Thu, Feb 13, 2014 at 8:21 AM, Koobas <koo...@gmail.com> wrote: > 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 <suresh4mas...@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 <jiangwen...@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! >> > >> > >