The code below gives me an error when I try to knit it into a pdf.
Otherwise it works properly.
actual_user_ratings <- train %>% left_join(actual_movie_ratings,by='movieId') %>%
group_by(userId) %>% summarise(b_y = mean(rating - mu - b_i))
Error in UseMethod("left_join") :
no applicable method for 'left_join' applied to an object of class "function"
Calls: ... eval -> _fseq -> freduce -> -> left_join