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你会如何对这个RDD进行排序?在考虑值的情况下,如何获取
我正在尝试按值对RDD进行排序,如果多个值相等,则需要按字典顺序将这些值按键排序。
代码:
JavaPairRDD <String,Long> rddToSort = rddMovieReviewReducedByKey.mapToPair(new PairFunction < Tuple2 < String, MovieReview > , String, Long > () {
@Override
public Tuple2 < String, Long > call(Tuple2 < String, MovieReview > t) throws Exception {
return new Tuple2 < String, Long > (t._1, t._2.count);
}
});
目前我所做的是使用takeOrdered
并提供一个CustomComperator
,但由于takeOrdered
无法处理大量数据,运行代码时它会不断退出(它会消耗大量操作系统无法处理的内存):
List < Tuple2 < String, Long >> rddSorted = rddMovieReviewReducedByKey.mapToPair(new PairFunction < Tuple2 < String, MovieReview > , String, Long > () {
@Override
public Tuple2 < String, Long > call(Tuple2 < String, MovieReview > t) throws Exception {
return new Tuple2 < String, Long > (t._1, t._2.count);
}
}).takeOrdered(newTopMovies, MapLongValueComparator.VALUE_COMP);
比较器:
static class MapLongValueComparator implements Comparator < Tuple2 < String, Long >> , Serializable {
private static final long serialVersionUID = 1L;
private static final MapLongValueComparator VALUE_COMP = new MapLongValueComparator();
@Override
public int compare(Tuple2 < String, Long > o1, Tuple2 < String, Long > o2) {
if (o1._2.compareTo(o2._2) == 0) {
return o1._1.compareTo(o2._1);
}
return -o1._2.compareTo(o2._2);
}
}
错误:
16/06/30 21:09:23 INFO scheduler.DAGScheduler: Job 18 failed: takeOrdered at MovieAnalyzer.java:708, took 418.149182 s
你会如何对这个RDD进行排序?在考虑值的情况下,如何获取
TopKMovies
,并且在键相等的情况下按字典顺序排序。谢谢。