/**
* Combines {@link Rating}s with the same user/item into one, with score as the sum of all of the
* scores.
*/
private JavaRDD<Rating> aggregateScores(JavaRDD<Rating> original) {
JavaPairRDD<Tuple2<Integer, Integer>, Double> tuples =
original.mapToPair(new RatingToTupleDouble());
JavaPairRDD<Tuple2<Integer, Integer>, Double> aggregated;
if (implicit) {
// For implicit, values are scores to be summed
aggregated = tuples.reduceByKey(Functions.SUM_DOUBLE);
} else {
// For non-implicit, last wins.
aggregated = tuples.foldByKey(Double.NaN, Functions.<Double>last());
}
return aggregated.map(new TupleToRatingFn());
}
private static void addIDsExtension(
PMML pmml, String key, RDD<Tuple2<Object, double[]>> features) {
List<String> ids = fromRDD(features).keys().map(Functions.toStringValue()).collect();
PMMLUtils.addExtensionContent(pmml, key, ids);
}