iterate through all userid and calculate similarity - not working, consider vectorize.

expedia.similarity.r

all_user_id <- unique(train$user_id)

similar_table<-list()
counter<-1
for (user in all_user_id) {
  similar_user<-c(user)
  current <- train[user_id == user,]
  for (next_user in all_user_id[-user]) {
    # calculate similarity
    # this is a test
    if (length(similar_user)==6) {
      break
    }
    append(similar_user, next_user)
  }
  similar_table[counter]<-similar_user
  counter<-counter+1
  print(counter)
}
names(similar_table)<-c('user', 'U1', 'U2', 'U3', 'U4', 'U5')


list1 <- list(c(1, 2, 3, 4))
dataframe1 <- data.frame(list1)