public static HashMap<Integer, Integer[]> movie_ratings(){
		HashMap<Integer, Integer[]> map = new HashMap<Integer, Integer[]>();
		for(int i = 0; i < train.size(); i++){
			if(!map.containsKey(Integer.parseInt(train.get(i)[1]))){
				Integer[] s = new Integer[usernum];
				for(int n = 0; n < s.length; n++)
					s[n] = 0;
				map.put(Integer.parseInt(train.get(i)[1]), s);
			}
			Integer[] ratings = map.get(Integer.parseInt(train.get(i)[1]));
			ratings[Integer.parseInt(train.get(i)[0]) - 1] = Integer.parseInt(train.get(i)[2]);
		}
		return map;
	}