Example usage for org.apache.mahout.cf.taste.recommender Rescorer rescore

Introduction

In this page you can find the example usage for org.apache.mahout.cf.taste.recommender Rescorer rescore.

Prototype

double rescore(T thing, double originalScore);

Source Link

Usage

From source file:net.myrrix.online.MostSimilarItemIterator.java

License:Apache License

@Override
public RecommendedItem next() {
    FastByIDMap.MapEntry<float[]> entry = Yiterator.next();
    long itemID = entry.getKey();

    if (userTagIDs.contains(itemID)) {
        return null;
    }//from ww  w.ja  v  a 2 s.co m

    for (long l : toItemIDs) {
        if (l == itemID) {
            return null;
        }
    }

    Rescorer<LongPair> rescorer1 = this.rescorer;
    float[] candidateFeatures = entry.getValue();
    double candidateFeaturesNorm = SimpleVectorMath.norm(candidateFeatures);
    double total = 0.0;

    int length = itemFeatures.length;
    for (int i = 0; i < length; i++) {
        long toItemID = toItemIDs[i];
        LongPair cachedPair = null;
        if (rescorer1 != null) {
            cachedPair = new LongPair(itemID, toItemID);
            if (rescorer1.isFiltered(cachedPair)) {
                return null;
            }
        }
        double similarity = SimpleVectorMath.dot(candidateFeatures, itemFeatures[i])
                / (candidateFeaturesNorm * itemFeatureNorms[i]);
        if (!LangUtils.isFinite(similarity)) {
            return null;
        }
        if (rescorer1 != null) {
            similarity = rescorer1.rescore(cachedPair, similarity);
            if (!LangUtils.isFinite(similarity)) {
                return null;
            }
        }
        total += similarity;
    }

    float result = (float) (total / length);
    Preconditions.checkState(LangUtils.isFinite(result), "Bad similarity value");
    delegate.set(itemID, result);
    return delegate;
}

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From source file:net.myrrix.online.MultiLongPairRescorer.java

License:Apache License

@Override
public double rescore(LongPair itemIDs, double value) {
    for (Rescorer<LongPair> rescorer : rescorers) {
        value = rescorer.rescore(itemIDs, value);
        if (Double.isNaN(value)) {
            return Double.NaN;
        }/*from   w ww  .  j ava2 s .  c o m*/
    }
    return value;
}

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