/**
* Check that we score items but do not provide scores for items the user has previously rated.
* User 5 has rated only item 8 previously.
*/
@Test
public void testItemScorerNoRating() {
long[] items = {7, 8};
ItemItemScorer scorer = session.get(ItemItemScorer.class);
assertThat(scorer, notNullValue());
SparseVector scores = scorer.score(5, LongArrayList.wrap(items));
assertThat(scores, notNullValue());
assertThat(scores.size(), equalTo(1));
assertThat(scores.get(7), not(notANumber()));
assertThat(scores.containsKey(8), equalTo(false));
}
/**
* Check that we score items but do not provide scores for items the user has previously rated.
* User 5 has rated only item 8 previously.
*/
@Test
public void testItemScorerChannels() {
long[] items = {7, 8};
ItemItemScorer scorer = session.get(ItemItemScorer.class);
assertThat(scorer, notNullValue());
SparseVector scores = scorer.score(5, LongArrayList.wrap(items));
assertThat(scores, notNullValue());
assertThat(scores.size(), equalTo(1));
assertThat(scores.get(7), not(notANumber()));
assertThat(
scores.getChannelVector(ItemItemScorer.NEIGHBORHOOD_SIZE_SYMBOL).get(7),
closeTo(1.0, 1.0e-5));
assertThat(scores.containsKey(8), equalTo(false));
long[] items2 = {7, 8, 9};
scorer = session.get(ItemItemScorer.class);
assertThat(scorer, notNullValue());
scores = scorer.score(2, LongArrayList.wrap(items2));
assertThat(
scores.getChannelVector(ItemItemScorer.NEIGHBORHOOD_SIZE_SYMBOL).get(9),
closeTo(3.0, 1.0e-5)); // 1, 7, 8
}
/**
* Get the keys of this vector sorted by the value of the items stored for each key.
*
* @param decreasing If {@code true}, sort in decreasing order.
* @return The sorted list of keys of this vector.
*/
public LongArrayList keysByValue(boolean decreasing) {
long[] skeys = keySet().toLongArray();
LongComparator cmp;
// Set up the comparator. We use the key as a secondary comparison to get
// a reproducible sort irrespective of sorting algorithm.
if (decreasing) {
cmp =
new AbstractLongComparator() {
@Override
public int compare(long k1, long k2) {
int c = Double.compare(get(k2), get(k1));
if (c != 0) {
return c;
} else {
return Longs.compare(k1, k2);
}
}
};
} else {
cmp =
new AbstractLongComparator() {
@Override
public int compare(long k1, long k2) {
int c = Double.compare(get(k1), get(k2));
if (c != 0) {
return c;
} else {
return Longs.compare(k1, k2);
}
}
};
}
LongArrays.quickSort(skeys, cmp);
return LongArrayList.wrap(skeys);
}