本文整理了Java中org.apache.flink.api.java.operators.UnsortedGrouping.first()方法的一些代码示例，展示了UnsortedGrouping.first()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。UnsortedGrouping.first()方法的具体详情如下：
包路径：org.apache.flink.api.java.operators.UnsortedGrouping
类名称：UnsortedGrouping
方法名：first

UnsortedGrouping.first介绍

[英]Returns a new set containing the first n elements in this grouped DataSet.
[中]返回包含此分组数据集中前n个元素的新集合。

代码示例

代码示例来源：origin: apache/flink

tupleDs.groupBy(2).first(1);
} catch (Exception e) {
  Assert.fail();
  tupleDs.groupBy(1, 3).first(10);
} catch (Exception e) {
  Assert.fail();
  tupleDs.groupBy(0).first(0);
  Assert.fail();
} catch (InvalidProgramException ipe) {
  tupleDs.groupBy(2).first(-1);
  Assert.fail();
} catch (InvalidProgramException ipe) {

代码示例来源：origin: apache/flink

@Test
public void testFirstNOnGroupedDS() throws Exception {
  /*
   * First-n on grouped data set
   */
  final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
  DataSet<Tuple3<Integer, Long, String>> ds = CollectionDataSets.get3TupleDataSet(env);
  DataSet<Tuple2<Long, Integer>> first = ds.groupBy(1).first(4)
      .map(new OneMapper2()).groupBy(0).sum(1);
  List<Tuple2<Long, Integer>> result = first.collect();
  String expected = "(1,1)\n(2,2)\n(3,3)\n(4,4)\n(5,4)\n(6,4)\n";
  compareResultAsText(result, expected);
}

代码示例来源：origin: apache/flink

private <K extends Tuple> void createFirstOperation(PythonOperationInfo info) {
  if (sets.isDataSet(info.parentID)) {
    DataSet<byte[]> op = sets.getDataSet(info.parentID);
    sets.add(info.setID, op
      .first(info.count).setParallelism(info.parallelism).name("First"));
  } else if (sets.isUnsortedGrouping(info.parentID)) {
    UnsortedGrouping<Tuple2<K, byte[]>> op = sets.getUnsortedGrouping(info.parentID);
    sets.add(info.setID, op
      .first(info.count).setParallelism(info.parallelism).name("First")
      .map(new KeyDiscarder<K>()).setParallelism(info.parallelism).name("FirstPostStep"));
  } else if (sets.isSortedGrouping(info.parentID)) {
    SortedGrouping<Tuple2<K, byte[]>> op = sets.getSortedGrouping(info.parentID);
    sets.add(info.setID, op
      .first(info.count).setParallelism(info.parallelism).name("First")
      .map(new KeyDiscarder<K>()).setParallelism(info.parallelism).name("FirstPostStep"));
  }
}

代码示例来源：origin: org.gradoop/gradoop-flink

@Override
public DataSet<WithCount<String>> execute(LogicalGraph graph) {
 return graph.getEdges()
  .map(new ToSourceIdWithLabel<>())
  .groupBy(0, 1)
  .first(1)
  .<Tuple1<String>>project(1)
  .map(new Tuple2FromTupleWithObjectAnd1L<>())
  .groupBy(0)
  .sum(1)
  .map(new Tuple2ToWithCount<>());
}

代码示例来源：origin: org.gradoop/gradoop-flink

@Override
public DataSet<WithCount<String>> execute(LogicalGraph graph) {
 return graph.getEdges()
  .map(new ToTargetIdWithLabel<>())
  .groupBy(0, 1)
  .first(1)
  .<Tuple1<String>>project(1)
  .map(new Tuple2FromTupleWithObjectAnd1L<>())
  .groupBy(0)
  .sum(1)
  .map(new Tuple2ToWithCount<>());
}

代码示例来源：origin: dbs-leipzig/gradoop

@Override
 public DataSet<WithCount<String>> execute(LogicalGraph graph) {
  return graph.getEdges()
   .map(new ToTargetIdWithLabel<>())
   .groupBy(0, 1)
   .first(1)
   .<Tuple1<String>>project(1)
   .map(new Tuple2FromTupleWithObjectAnd1L<>())
   .groupBy(0)
   .sum(1)
   .map(new Tuple2ToWithCount<>());
 }
}

代码示例来源：origin: dbs-leipzig/gradoop

@Override
 public DataSet<WithCount<String>> execute(LogicalGraph graph) {
  return graph.getEdges()
   .map(new ToSourceIdWithLabel<>())
   .groupBy(0, 1)
   .first(1)
   .<Tuple1<String>>project(1)
   .map(new Tuple2FromTupleWithObjectAnd1L<>())
   .groupBy(0)
   .sum(1)
   .map(new Tuple2ToWithCount<>());
 }
}