@Override
public void process(Pair<Long, Iterable<NumericIDValue>> input, Emitter<String> emitter) {
StringLongMapping mapping = idMapping.getIDMapping();
Iterable<NumericIDValue> recs = TopN.selectTopN(input.second().iterator(), numRecs);
String userID = mapping.toString(input.first());
for (NumericIDValue rec : recs) {
emitter.emit(
DelimitedDataUtils.encode(
',', userID, mapping.toString(rec.getID()), Float.toString(rec.getValue())));
}
}
@Override
public void process(
Pair<Pair<Long, Integer>, Iterable<NumericIDValue>> input,
Emitter<Pair<Long, NumericIDValue>> emitter) {
Pair<Long, Integer> key = input.first();
long currentUserID = key.first();
if (key.second() == BEFORE) {
// Last old data had no match, just output it
if (previousUserPrefs != null) {
Preconditions.checkNotNull(previousUserID);
output(previousUserID, previousUserPrefs, null, null, emitter);
previousUserPrefs = null;
previousUserID = null;
}
LongFloatMap oldPrefs = new LongFloatMap();
for (NumericIDValue itemPref : input.second()) {
float oldPrefValue = itemPref.getValue();
Preconditions.checkState(!Float.isNaN(oldPrefValue), "No prior pref value?");
// Apply decay factor here, if applicable:
oldPrefs.increment(itemPref.getID(), doDecay ? oldPrefValue * decayFactor : oldPrefValue);
}
previousUserPrefs = oldPrefs;
previousUserID = currentUserID;
} else {
// Last old data had no match, just output it
if (previousUserPrefs != null && currentUserID != previousUserID) {
Preconditions.checkNotNull(previousUserID);
output(previousUserID, previousUserPrefs, null, null, emitter);
previousUserPrefs = null;
previousUserID = null;
}
LongFloatMap newPrefs = new LongFloatMap();
LongSet removedItemIDs = new LongSet();
for (NumericIDValue itemPref : input.second()) {
long itemID = itemPref.getID();
float newPrefValue = itemPref.getValue();
if (Float.isNaN(newPrefValue)) {
removedItemIDs.add(itemID);
} else {
newPrefs.increment(itemID, newPrefValue);
}
}
output(currentUserID, previousUserPrefs, newPrefs, removedItemIDs, emitter);
previousUserPrefs = null;
previousUserID = null;
}
}