private static double[] doTestRandomVecs(LongObjectMap<float[]> Y, float[] userVec) {
LocationSensitiveHash lsh = new LocationSensitiveHash(Y, 0.1, 20);
LongSet candidates = new LongSet();
float[][] userVecs = {userVec};
for (Iterator<LongObjectMap.MapEntry<float[]>> candidatesIterator :
lsh.getCandidateIterator(userVecs)) {
while (candidatesIterator.hasNext()) {
candidates.add(candidatesIterator.next().getKey());
}
}
List<Long> topIDs = findTopRecommendations(Y, userVec);
double score = 0.0;
double maxScore = 0.0;
int intersectionSize = 0;
for (int i = 0; i < topIDs.size(); i++) {
double value = LN2 / Math.log(2.0 + i);
long id = topIDs.get(i);
if (candidates.contains(id)) {
intersectionSize++;
score += value;
}
maxScore += value;
}
double percentTopRecsConsidered = (double) intersectionSize / topIDs.size();
double ndcg = maxScore == 0.0 ? 0.0 : score / maxScore;
double percentAllItemsConsidered = (double) candidates.size() / Y.size();
return new double[] {percentTopRecsConsidered, ndcg, percentAllItemsConsidered};
}
public int size() {
return reverseMapping.size();
}