private static void addDatumAndCreateIfNeeded(
long itemID, float value, FastByIDMap<RunningAverage> averages) {
RunningAverage itemAverage = averages.get(itemID);
if (itemAverage == null) {
itemAverage = new FullRunningAverage();
averages.put(itemID, itemAverage);
}
itemAverage.addDatum(value);
}
@Override
public void setPreference(long userID, long itemID, float value) throws TasteException {
DataModel dataModel = getDataModel();
double prefDelta;
try {
Float oldPref = dataModel.getPreferenceValue(userID, itemID);
prefDelta = oldPref == null ? value : value - oldPref;
} catch (NoSuchUserException nsee) {
prefDelta = value;
}
super.setPreference(userID, itemID, value);
try {
buildAveragesLock.writeLock().lock();
RunningAverage itemAverage = itemAverages.get(itemID);
if (itemAverage == null) {
RunningAverage newItemAverage = new FullRunningAverage();
newItemAverage.addDatum(prefDelta);
itemAverages.put(itemID, newItemAverage);
} else {
itemAverage.changeDatum(prefDelta);
}
RunningAverage userAverage = userAverages.get(userID);
if (userAverage == null) {
RunningAverage newUserAveragae = new FullRunningAverage();
newUserAveragae.addDatum(prefDelta);
userAverages.put(userID, newUserAveragae);
} else {
userAverage.changeDatum(prefDelta);
}
overallAveragePrefValue.changeDatum(prefDelta);
} finally {
buildAveragesLock.writeLock().unlock();
}
}
@Test
public void testEvaluate() throws Exception {
DataModel model = getDataModel();
Recommender recommender1 = new SlopeOneRecommender(model);
Recommender recommender2 = new ItemAverageRecommender(model);
RecommenderEvaluator evaluator = new PreferenceBasedRecommenderEvaluator();
RunningAverage tracker = new FullRunningAverage();
evaluator.evaluate(recommender1, recommender2, 100, tracker, Formula.MEANRANK);
double eval = tracker.getAverage();
assertEquals(0.185294508934021, eval, EPSILON);
}
private float doEstimatePreference(long userID, long itemID) {
buildAveragesLock.readLock().lock();
try {
RunningAverage itemAverage = itemAverages.get(itemID);
if (itemAverage == null) {
return Float.NaN;
}
RunningAverage userAverage = userAverages.get(userID);
if (userAverage == null) {
return Float.NaN;
}
double userDiff = userAverage.getAverage() - overallAveragePrefValue.getAverage();
return (float) (itemAverage.getAverage() + userDiff);
} finally {
buildAveragesLock.readLock().unlock();
}
}
@Override
public void removePreference(long userID, long itemID) throws TasteException {
DataModel dataModel = getDataModel();
Float oldPref = dataModel.getPreferenceValue(userID, itemID);
super.removePreference(userID, itemID);
if (oldPref != null) {
try {
buildAveragesLock.writeLock().lock();
RunningAverage itemAverage = itemAverages.get(itemID);
if (itemAverage == null) {
throw new IllegalStateException("No preferences exist for item ID: " + itemID);
}
itemAverage.removeDatum(oldPref);
RunningAverage userAverage = userAverages.get(userID);
if (userAverage == null) {
throw new IllegalStateException("No preferences exist for user ID: " + userID);
}
userAverage.removeDatum(oldPref);
overallAveragePrefValue.removeDatum(oldPref);
} finally {
buildAveragesLock.writeLock().unlock();
}
}
}
private void buildAverageDiffs() throws TasteException {
try {
buildAveragesLock.writeLock().lock();
DataModel dataModel = getDataModel();
LongPrimitiveIterator it = dataModel.getUserIDs();
while (it.hasNext()) {
long userID = it.nextLong();
PreferenceArray prefs = dataModel.getPreferencesFromUser(userID);
int size = prefs.length();
for (int i = 0; i < size; i++) {
long itemID = prefs.getItemID(i);
float value = prefs.getValue(i);
addDatumAndCreateIfNeeded(itemID, value, itemAverages);
addDatumAndCreateIfNeeded(userID, value, userAverages);
overallAveragePrefValue.addDatum(value);
}
}
} finally {
buildAveragesLock.writeLock().unlock();
}
}
