I am abit confused by the user dataset in the lab 2 of week2,
so there are multiple rows for user id = 1, but the values across the rows for user id = 1 are different. for example, the rating avg for row 2 (which belongs to user 1) is 0.5, but on the last row rating avg is for user -0.2. so is each row user i’s reaction to movie j? In that case, how is the rating avg calculated, since it should be just one number?
