Example usage for org.apache.mahout.cf.taste.impl.common RunningAverage removeDatum

Introduction

In this page you can find the example usage for org.apache.mahout.cf.taste.impl.common RunningAverage removeDatum.

Prototype

void removeDatum(double datum);

Source Link

Usage

From source file:net.ufida.info.mahout.common.MemoryDiffStorage.java

License:Apache License

@Override
public void removeItemPref(long userID, long itemIDA, float prefValue) throws TasteException {
    PreferenceArray userPreferences = dataModel.getPreferencesFromUser(userID);
    try {//  w  w  w  .j  av a2 s  .c o m
        buildAverageDiffsLock.writeLock().lock();

        FastByIDMap<RunningAverage> aMap = averageDiffs.get(itemIDA);

        int length = userPreferences.length();
        for (int i = 0; i < length; i++) {

            long itemIDB = userPreferences.getItemID(i);
            float bValue = userPreferences.getValue(i);

            if (itemIDA < itemIDB) {

                if (aMap != null) {
                    RunningAverage average = aMap.get(itemIDB);
                    if (average != null) {
                        if (average.getCount() <= 1) {
                            aMap.remove(itemIDB);
                        } else {
                            average.removeDatum(bValue - prefValue);
                        }
                    }
                }

            } else if (itemIDA > itemIDB) {

                FastByIDMap<RunningAverage> bMap = averageDiffs.get(itemIDB);
                if (bMap != null) {
                    RunningAverage average = bMap.get(itemIDA);
                    if (average != null) {
                        if (average.getCount() <= 1) {
                            aMap.remove(itemIDA);
                        } else {
                            average.removeDatum(prefValue - bValue);
                        }
                    }
                }

            }
        }

    } finally {
        buildAverageDiffsLock.writeLock().unlock();
    }
}

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