recommendation engine - When execute KNN on user based collaborative filter? -


i have seen codes , examples of user based collaborative filter executes knn before calculates similarities, , others executes after, means, executes knn on similarities matrix.

so doubt when calculates knn algorithm, on data matrix before calculates similarities, or on similarities matrix?

references:

https://github.com/mhahsler/recommenderlab/blob/master/r/recom_ubcf.r

dietmar jannach, markus zanker, alexander felfernig, gerhard friedrich - recommender systems introduction - cambridge university press (2010)

a cuda-enabled parallel implementation of collaborative filtering zhongya wanga, ying liua, , pengshan ma


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