Package io.deephaven.api.agg

Class FirstRowKey

java.lang.Object

io.deephaven.api.agg.FirstRowKey

All Implemented Interfaces:

Aggregation

@Immutable
public abstract class FirstRowKey
extends Object
implements Aggregation

An aggregation that provides a single output column with the first row key from the input table for each aggregation group in the result.

The primary use case for this aggregation is to allow for a subsequent sort on the output column to order aggregated data by current first occurrence in the input table rather than encounter order.

Nested Class Summary

Nested classes/interfaces inherited from interface io.deephaven.api.agg.Aggregation

Aggregation.Visitor

Constructor Summary

Constructors

Constructor	Description
FirstRowKey()

Method Summary

Modifier and Type	Method	Description
abstract ColumnName	column()
static FirstRowKey	of(ColumnName name)
static FirstRowKey	of(String x)
final <V extends Aggregation.Visitor> V	walk(V visitor)	Glue method to deliver this Aggregation to a AggSpec.Visitor.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

FirstRowKey

public FirstRowKey()

Method Details

of

public static FirstRowKey of(ColumnName name)

of

public static FirstRowKey of(String x)

column

@Parameter
public abstract ColumnName column()

walk

public final <V extends Aggregation.Visitor> V walk(V visitor)

Description copied from interface: Aggregation

Glue method to deliver this Aggregation to a AggSpec.Visitor.

Specified by:

walk in interface Aggregation

Parameters:

visitor - The visitor

Returns:

The visitor