CODEWITHSUNDEEP
mahout
laxmi
laxmi

Reputation: 107

How mahout user based recommendation works?

I am using generic user based recommender of mahout taste api to generate recommendations..

I know it recommends based on ratings given to past users..I am not getting mathematics behind its selection of recommended item..for example..

for user id 58

itemid ratings 

 231 5

 235 5.5

 245 5.88

3 neighbors are,with itemid and ratings as,{231 4,254 5,262 2,226 5}

{235 3,245 4,262 3} {226 4,262 3} It recommends me 226 how?

With advance thanks,

Upvotes: 1

Views: 1445

Answers (1)

Sbhklr
Sbhklr

Reputation: 2703

It depends on the UserSimilarity and the UserNeighborhood you have chosen for your recommender. But in general the algorithm works as follows for user u:

for every other user w
    compute a similarity s between u and w
    retain the top users, ranked by similarity, as a neighborhood n
for every item i that some user in n has a preference for, but that u has no preference for yet
    for every other user v in n that has a preference for i
        compute a similarity s between u and v
        incorporate v's preference for i, weighted by s, into a running average

Source: Mahout in Action http://manning.com/owen/

Upvotes: 1

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