Aggregate算⼦求最⼤值
彩色钥匙package comic.ding
import org.apache.flink.api.java.aggregation.Aggregations
脏内裤import org.apache.flink.api.scala.{AggregateDataSet, DataSet, ExecutionEnvironment}
一y
全屏壁纸import org.apache.flink.streaming.api.scala._
llection.mutable
object AggregateDemo {
def main(args: Array[String]): Unit = {
鲑鱼做法val env = ExecutionEnvironment
val data = new mutable.MutableList[(Int, String, Double)]
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data.+=((1, "yuwen", 89.0))
data.+=((2, "shuxue", 92.2))
data.+=((3, "yuwen", 89.99))
// 构建数据源
val input: DataSet[(Int, String, Double)] = env.fromCollection(data)文明出行
val value: AggregateDataSet[(Int, String, Double)] = upBy(1).aggregate(Aggregations.MAX,2)
value.print()
}
}
注意：
1，Aggregate只能作⽤于元组上
2，使⽤aggregate，只能使⽤字段索引名或索引名称来进⾏分组 groupBy(0) ，否则会报以下错误:
Exception in thread "main" java.lang.UnsupportedOperationException: Aggregate does not support grouping with KeySelector functions, yet.
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