我的四个字段,分别为年份,电影编号,电影名字,评价平均分,现在我有一个需求,按照年份进行分组。将分组以后的数据按照评价平均分进行倒序排序,如果评价平均分大小一样,按照电影名自然排序。请帮我有java语言实现这个sparkrdd需求
时间: 2023-12-10 20:04:11 浏览: 62
好的,以下是Java语言实现的Spark RDD代码:
```java
JavaRDD<String> rdd = sc.textFile("path/to/file"); // 读取数据文件
JavaPairRDD<Integer, Tuple2<String, Double>> pairRdd = rdd.mapToPair(line -> {
String[] fields = line.split(",");
int year = Integer.parseInt(fields[0]);
String movieId = fields[1];
String movieName = fields[2];
double rating = Double.parseDouble(fields[3]);
return new Tuple2<>(year, new Tuple2<>(movieName, rating));
}).groupByKey().flatMapToPair(yearMovies -> {
List<Tuple2<Double, String>> ratings = new ArrayList<>();
for (Tuple2<String, Double> movieRating : yearMovies._2()) {
ratings.add(new Tuple2<>(movieRating._2(), movieRating._1()));
}
Collections.sort(ratings, Collections.reverseOrder());
List<Tuple2<Double, String>> sortedRatings = new ArrayList<>();
double lastRating = -1.0;
for (Tuple2<Double, String> rating : ratings) {
if (rating._1() != lastRating) {
sortedRatings.add(rating);
lastRating = rating._1();
} else {
sortedRatings.add(new Tuple2<>(rating._1(), rating._2()));
}
}
List<Tuple2<String, Double>> sortedMovies = new ArrayList<>();
for (Tuple2<Double, String> rating : sortedRatings) {
sortedMovies.add(new Tuple2<>(rating._2(), rating._1()));
}
return sortedMovies.iterator();
});
pairRdd.foreach(pair -> System.out.println(pair._1() + "," + pair._2()._1() + "," + pair._2()._2()));
```
首先,我们将每一行数据转换为键值对,其中键为年份,值为电影名和评价平均分的元组。然后,我们按照年份进行分组。接下来,对于每个年份的电影,我们将其评价平均分和电影名存储为元组,并对评价平均分进行倒序排序,如果评价平均分一样,按照电影名自然排序。最后,我们将排序后的电影名和评价平均分存储为键值对,并输出结果。
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