Example usage for org.apache.mahout.cf.taste.hadoop RecommendedItemsWritable RecommendedItemsWritable

Introduction

In this page you can find the example usage for org.apache.mahout.cf.taste.hadoop RecommendedItemsWritable RecommendedItemsWritable.

Prototype

public RecommendedItemsWritable(List<RecommendedItem> recommended) 

Source Link

Usage

From source file:nl.gridline.zieook.inx.movielens.AggregateAndRecommendReducer.java

License:Apache License

/**
 * find the top entries in recommendationVector, map them to the real itemIDs and write back the result
 *//*from w ww  . j av a  2 s  . c  om*/
private void writeRecommendedItems(VarLongWritable userID, Vector recommendationVector, Context context)
        throws IOException, InterruptedException {
    Queue<RecommendedItem> topItems = new PriorityQueue<RecommendedItem>(recommendationsPerUser + 1,
            Collections.reverseOrder(ByValueRecommendedItemComparator.getInstance()));

    Iterator<Vector.Element> recommendationVectorIterator = recommendationVector.iterateNonZero();
    while (recommendationVectorIterator.hasNext()) {
        Vector.Element element = recommendationVectorIterator.next();
        int index = element.index();

        long itemID = indexItemIDMap.get(index);
        if (itemsToRecommendFor == null || itemsToRecommendFor.contains(itemID)) {
            float value = (float) element.get();
            if (!Float.isNaN(value)) {
                if (topItems.size() < recommendationsPerUser) {
                    topItems.add(new GenericRecommendedItem(itemID, value));
                } else if (value > topItems.peek().getValue()) {
                    topItems.add(new GenericRecommendedItem(itemID, value));
                    topItems.poll();
                }
            }
        }
    }

    if (!topItems.isEmpty()) {
        List<RecommendedItem> recommendations = new ArrayList<RecommendedItem>(topItems.size());
        recommendations.addAll(topItems);
        Collections.sort(recommendations, ByValueRecommendedItemComparator.getInstance());
        context.write(userID, new RecommendedItemsWritable(recommendations));
    }
}

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