docstr: Incorporating implicit feedback in the SVD: Sum (j E N(u)) Yj
  
  :param user: User ID
  :type user: int
  
  :return: Sum of y vectors for seen items of user
docstr_tok: ["Incorporating","implicit","feedback","in","the","SVD",":","Sum","(","j","E","N","(","u",")",")","Yj",":","param","user",":","User","ID",":","type","user",":","int",":","return",":","Sum","of","y","vectors","for","seen","items","of","user"]
code: def y_sum_rows(self, user):
      """
      Incorporating implicit feedback in the SVD: Sum (j E N(u)) Yj
  
      :param user: User ID
      :type user: int
  
      :return: Sum of y vectors for seen items of user
  
      """
  
      sum_imp = np.zeros(self.factors)
      for ui in self.items_id_seen_by_user[user]:
          sum_imp += self.y[ui]
      return sum_imp / self.n_u[user]
  
file_path: CaseRecommender/caserec/recommenders/rating_prediction/svdplusplus.py
imports: import numpy
  from caserec.recommenders.rating_prediction.matrixfactorization import MatrixFactorization
label_desc: Use image node_id 6 for calling the SVDPlusPlus obj's underlying member method code with example usage: obj.y_sum_rows(user) and returns: unknown