Ratings.make(42, 22, 3));
UserHistory<Event> history = History.forUser(42, events);
assertThat(history, hasSize(3));
SparseVector v = history.memoize(RatingVectorUserHistorySummarizer.SummaryFunction.INSTANCE);
assertThat(v.size(), equalTo(3));
assertThat(v.mean(), equalTo(3.0));
assertThat(history.memoize(RatingVectorUserHistorySummarizer.SummaryFunction.INSTANCE),
sameInstance(v));
}
@Test