Examples of cascading.operation.aggregator.First

cascading.operation.aggregator.First
Class First is an {@link Aggregator} that returns the first {@link Tuple} encountered in a grouping.
By default, it returns the first Tuple of {@link Fields#ARGS} found.
If {@code firstN} is given, Tuples with each of the first N number of Tuples encountered are returned. That is,this Aggregator will return at maximum N tuples per grouping.
Be sure to set the {@link cascading.pipe.GroupBy} {@code sortFields} to control which Tuples are seen first.

    // transpose values in fields by natural sort order
    pipe = new Each( pipe, new SortElements( new Fields( "name1", "rate1" ), new Fields( "name2", "rate2" ) ) );


    // unique the pipe
    pipe = new GroupBy( pipe, Fields.ALL );
    pipe = new Every( pipe, Fields.ALL, new First(), Fields.RESULTS );


    // calculate square of diff
    Function sqDiff = new Identity( new Fields( "score" ) )
    {
    public void operate( FlowProcess flowProcess, FunctionCall functionCall )

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   * @param threshold      of type int
   */
  @ConstructorProperties({"name", "pipes", "groupingFields", "firstFields", "threshold"})
  public FirstBy( String name, Pipe[] pipes, Fields groupingFields, Fields firstFields, int threshold )
    {
    super( name, pipes, groupingFields, firstFields, new FirstPartials( firstFields ), new First( firstFields ), threshold );
    }

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   * @param firstFields of type Fields
   */
  @ConstructorProperties({"firstFields"})
  public FirstBy( Fields firstFields )
    {
    super( firstFields, new FirstPartials( firstFields ), new First( firstFields ) );
    }

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   * @param firstFields of type Fields
   */
  @ConstructorProperties({"argumentFields", "firstFields"})
  public FirstBy( Fields argumentFields, Fields firstFields )
    {
    super( argumentFields, new FirstPartials( argumentFields ), new First( firstFields ) );
    }

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