List<Rating> ratings = new ArrayList<Rating>();
ratings.add(new SimpleRating(1, 2, 3.0, 3));
ratings.add(new SimpleRating(1, 5, 2.3, 4));
ratings.add(new SimpleRating(1, 3, 4.5, 5));
ratings.add(new SimpleRating(1, 5, 3.7, 6));
MutableSparseVector urv = Ratings.userRatingVector(ratings);
assertThat(urv.isEmpty(), equalTo(false));
assertThat(urv.size(), equalTo(3));
assertThat(urv.get(2), closeTo(3.0, 1.0e-6));
assertThat(urv.get(3), closeTo(4.5, 1.0e-6));
assertThat(urv.get(5), closeTo(3.7, 1.0e-6));
assertThat(urv.containsKey(1), equalTo(false));
}