You are right Koobas, my answer was on the assumption that item-based
NN is used (but I noticed that user-based NN is being used). So my
answer is not correct, sorry.
Currently, I could not understand the exact reason why user 5 is not
getting any recommendations, as you said user 5 should get 107.
On Thu, Feb 13, 2014 at 3:21 PM, 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!
>> >
>>
